Plaquelike Clearings Induced by Antimicrobial Agents on Lawns of Pseudomonas aeruginosa

Plaques similar in appearance to those induced by phage were observed adjacent to chloramphenicol and tetracycline discs on Pseudomonas aeruginosa lawns used for the determination of antibiotic susceptibility. Thirteen strains were selected for study, 10 of which exhibited the plaquing phenomenon. The ability to form plaques induced by tetracycline was not related to any of the biochemical properties of the strains studied, their overall antimicrobial susceptibility pattern, or their pathological source. Some pseudomonad strains were capable of pyocin production; however, the relationship between plaque formation and pyocin production was not apparent. Supernatant fluids of resuspended plaque contents of eight strains originally demonstrating clearings could induce plaques on sensitive indicator lawns only when collected from tetracycline-induced plaque areas; supernatant fluids of the same strains could not produce clearings without previous exposure to the drug. Of the eight supernatant fluids capable of plaque induction, three were active on their homologous indicator lawns. In a subsequent survey of 95 P. aeruginosa strains, it was found that 28 isolates exhibited plaques. Of these, 17 were associated with tetracycline, 7 were associated with chloramphenicol, 3 were associated with triple sulfa; and 1 was associated with nalidixic acid.

Adiponectin attenuation of endocrine function within human term trophoblast cells

The hormone adiponectin has been shown to be important in maintaining insulin sensitivity throughout the body, whereas potential effects on the placenta have not been assessed. Pregnancy constitutes a unique physiological environment in which metabolism has a profound effect on the health of both the mother and the developing fetus. It is imperative that a delicate balance in glucose delivery be maintained between maternal tissues and the fetal/placental unit. Adiponectin's role in regulating peripheral insulin responsiveness suggests it may be a factor in maintaining this balance during gestation as well. Examination of human cytotrophoblast cells revealed that mRNA for both adiponectin receptors, adipoR1 and adipoR2, are abundantly expressed at term. We were, however, unable to reliably detect mRNA for adiponectin in primary cytotrophoblasts. Expression of both receptors was maintained after induction of syncytium formation by exogenous epidermal growth factor treatment. Treatment of cytotrophoblasts with adiponectin resulted in a significant drop, as assessed by quantitative RT-PCR, in expression for a number of genes involved in the endocrine function of the placenta, including the chorionic gonadotropin subunits, placental lactogen, and some steroidogenic enzymes. Immunofluorescent staining for connexin 43 and desmoplakin in primary trophoblasts revealed that adiponectin does not inhibit syncytialization of trophoblast cells in culture. Taken together, these data describe a novel role for maternal adiponectin in regulating the placental environment. Determination of the effects of such adipokines on the maternal-fetal interface is increasingly important, because the incidence of pregnancies complicated by gestational diabetes remains a significant health problem in developed countries.

Noggin maintains pluripotency of human embryonic stem cells grown on Matrigel

OBJECTIVE

Spontaneous differentiation of human embryonic stem cell (hESC) cultures is a major concern in stem cell research. Physical removal of differentiated areas in a stem cell colony is the current approach used to keep the cultures in a pluripotent state for a prolonged period of time. All hESCs available for research require unidentified soluble factors secreted from feeder layers to maintain the undifferentiated state and pluripotency. Under experimental conditions, stem cells are grown on various matrices, the most commonly used being Matrigel.

MATERIALS AND METHODS

We propose an alternative method to prevent spontaneous differentiation of hESCs grown on Matrigel that uses low amounts of recombinant noggin. We make use of the porosity of Matrigel to serve as a matrix that traps noggin and gradually releases it into the culture to antagonize bone morphogenetic proteins (BMP). BMPs are known to initiate differentiation of hESCs and are either present in the conditioned medium or are secreted by hESCs themselves.

RESULTS

hESCs grown on Matrigel supplemented with noggin in conditioned medium from feeder layers (irradiated mouse embryonic fibroblasts) retained both normal karyotype and markers of hESC pluripotency for 14 days. In addition, these cultures were found to have increased cell proliferation of stem cells as compared to hESCs grown on Matrigel alone.

CONCLUSION

Noggin can be utilized for short term prevention of spontaneous differentiation of stem cells grown on Matrigel.

Developmental expression of the homeobox protein Distal-less 3 and its relationship to progesterone production in mouse placenta

Distal-less 3 (Dlx3) is a homeobox factor that functions as a placental-specific transcriptional regulator. Dlx3 null mice (-/-) have compromised placental development and do not survive in utero past embryonic day (E) 9.5. The current studies were undertaken to examine the expression of Dlx3 in mouse placenta during gestation, and to determine whether Dlx3 was involved in placental progesterone production. Dlx3 was not detectable at E8.5 but was detected in E9.5 placenta with continuing but diminished expression through E15.5. Dlx3 immuno-localization was restricted to the labyrinth, was nuclear and was found in cytokeratin-positive cells. Previous studies in choriocarcinoma cell lines support the conclusion that Dlx3 is required for expression of 3'-hydroxysteroid dehydrogenase VI (3betaHSD VI), an obligate enzyme in the production of progesterone by trophoblast giant cells. In a rat trophoblast stem cell line (Rcho-1), Dlx3 expression was non-detectable in Rcho-1 cells induced to differ-entiate using mitogen withdrawal. In vitro progesterone production in placental cultures and 3betaHSD VI mRNA from Dlx3 (+/+), (+/-) and (-/-) mice were equivalent. In situ hybridization for 3betaHSD VI revealed mRNA expression restricted to trophoblast giants cells with no detectable expression in the labyrinth suggesting that Dlx3 and 3betaHSD VI were not colocalized within the placenta. These studies support the conclusion that Dlx3 protein expression is restricted to the labyrinth region of the murine placenta into late gestation and that Dlx3 does not appear to be expressed in trophoblast giant cells. Further, loss of Dlx3 was not correlated with synthesis of progesterone from E9.5 mouse placentas.

An early growth response protein (Egr) 1 cis-element is required for gonadotropin-releasing hormone-induced mitogen-activated protein kinase phosphatase 2 gene expression

In pituitary gonadotropes, gonadotropin-releasing hormone (GnRH) activates all three major mitogen-activated protein kinase (MAPK) cascades. The MAPKs play key roles in transcriptional activation of GnRH-responsive genes. MAPK phosphatases (MKPs) are dual specificity protein phosphatases involved in feedback regulation of MAPK activity. Previous studies indicate that GnRH activates MKP-2 expression in gonadotropes, dependent upon activation of multiple MAPKs and discrete Ca(2+) signals. To further understand the transcriptional mechanism(s) of MKP-2 induction by GnRH, we studied the activity of a 198-nucleotide MKP-2 proximal promoter region that supports GnRH responsiveness in reporter gene assays. Functional analysis of the MKP-2 promoter confirmed a requirement for the protein kinase C-extracellular signal-regulated kinase (ERK) pathway and VGCC-derived Ca(2+) signals in transcriptional activation of the MKP-2 gene. However, the inhibitory effect of thapsigargin on MKP-2 protein expression previously identified was not mediated at the level of promoter activation, suggesting a distinct mechanism for the action of thapsigargin-sensitive Ca(2+) signals. MGRE (MKP-2 GnRH response element) within the MKP-2 promoter mediated promoter activation through the protein kinase C-ERK pathway. The zinc finger transcription factor Egr-1 was identified in the MGRE-binding complex. Egr-1/MGRE binding was induced by GnRH in an ERK-dependent manner. Transcriptional activity of Egr-1 protein was enhanced by GnRH treatment. In addition, overexpression of the Egr-interacting protein, NAB1, resulted in increased GnRH-stimulated MKP-2 gene transcription. Consistent with the putative role of Egr-1 in MKP-2 promoter regulation, Egr-1 protein expression closely correlated with the expression of MKP-2 protein in alpha T3-1 cells. Together, these data suggest that Egr-1 may be a key factor in mediating GnRH-dependent transcriptional activation of the MKP-2 gene.

Component rotation and anterior knee pain after total knee arthroplasty

All patients undergoing cruciate-retaining primary total knee arthroplasty for degenerative osteoarthritis at one center were studied prospectively. Clinical and radiographic followup was obtained at a minimum 5 years in 102 knees in 73 patients. Patients were asked specifically about the presence of the pain in the anterior aspect of the knee in the vicinity of the patella and rated the severity of the pain on a visual analog scale. Significant anterior knee pain rating at least 3 of 10 on the visual analog scale was present in 16 knees (13 patients). Eleven patients with 14 symptomatic knees agreed to undergo computed tomography scanning to accurately determine the rotation of the tibial and femoral components. The epicondylar axis and tibial tubercle were used as references using a previously validated technique. A control group of 11 asymptomatic patients (14 knees), matched for age, gender, and length of followup also underwent computed tomography scanning. All patients in both groups had normal axial alignment. There was a highly significant difference in tibial component rotation between the two groups with the patients with anterior knee pain averaging 6.2 degrees internal rotation compared with 0.4 degrees external rotation in the control group. There also was a significant difference in combined component rotation with the patients with anterior knee pain averaging 4.7 degrees internal rotation compared with 2.6 degrees external rotation in the control group. There was no significant difference in the degree of radiographic patellar tilt or patellar subluxation between the two groups. Patients with combined component internal rotation were more than five times as likely to experience anterior knee pain after total knee arthroplasty compared with those with combined component external rotation. Component malrotation is a significant factor in the development of anterior knee pain after total knee arthroplasty.

Immortalization of equine trophoblast cell lines of chorionic girdle cell lineage by simian virus-40 large T antigen

Immortalized cell lines have many potential experimental applications including the analysis of molecular mechanisms underlying cell-specific gene expression. We have utilized a recombinant retrovirus encoding the simian virus-40 (SV-40) large T antigen to construct several immortalized cell lines of equine chorionic girdle cell lineage - the progenitor cells that differentiate into the equine chorionic gonadotropin (eCG) producing endometrial cups. Morphologically, the immortalized cell lines appear similar to normal chorionic girdle cells. Derivation of the immortalized cell lines from a chorionic girdle cell lineage was verified by immunological detection of cell-surface antigens specific to equine invasive trophoblasts. The cell lines differed, however, from mature chorionic girdle cells or endometrial cup cells in that they did not produce eCG and did express MHC class I molecules. Thus, these cell lines appear to have been arrested at a stage of development prior to final differentiation into endometrial cup cells. It was also determined that some of these cell lines as well as endometrial cups express the estrogen receptor-related receptor beta gene, but not the glial cell missing gene (GCMa) both of which are expressed in the murine and human placenta. Among these cell lines, three (eCG 50.5, 100.6 and 500.1) express eCG alpha mRNA. Since regulation of eCG alpha subunit gene is largely unknown, we investigated the signal transduction pathways regulating the eCG alpha subunit gene. Both activators of protein kinase A (PKA) and protein kinase C (PKC) induced the expression of eCG alpha subunit expression 3.2 (P<0.05)- and 1.9 (P<0.05)-fold respectively, in the eCG 500.1 cell line. However, activation of these pathways failed to induce eCG beta subunit expression. In conclusion, lines of equine trophoblast cells have been immortalized that display markers characteristic of those with the equine chorionic girdle and endometrial cup cell lineage. A subset of these cells expresses the eCG alpha subunit gene which is responsive to activators of the PKA and PKC signal transduction pathways.

Patellar resurfacing in total knee arthroplasty. A prospective, randomized, double-blind study with five to seven years of follow-up

BACKGROUND

Whether to resurface the patella during a primary total knee arthroplasty performed for the treatment of degenerative osteoarthritis remains a controversial issue. Parameters that have been suggested as being useful in guiding this decision include patient height and weight, the presence of anterior knee pain preoperatively, and the grade of chondromalacia encountered intraoperatively. The purpose of this study was to determine whether these parameters were predictive of the clinical result following total knee arthroplasty with or without patellar resurfacing.

METHODS

Eighty-six patients (118 knees) undergoing primary total knee arthroplasty for the treatment of osteoarthritis were enrolled in a prospective, randomized, double-blind study. All patients received the same posterior-cruciate-sparing total knee prosthetic components. Patients were randomized to treatment with or without resurfacing of the patella. Evaluations consisted of the determination of a Knee Society clinical score, the completion of a patient satisfaction questionnaire, specific questions relating to patellofemoral symptoms, and radiographs. Sixty-seven patients (ninety-three knees) were followed for a minimum of five years (range, sixty to eighty-four months; average, 70.5 months).

RESULTS

With the numbers available, there was no significant difference between the groups treated with and without resurfacing with regard to the overall Knee Society score or the pain and function subscores. Obesity, the degree of patellar chondromalacia, and the presence of preoperative anterior knee pain did not predict postoperative clinical scores or the presence of postoperative anterior knee pain.

CONCLUSIONS

The occurrence of anterior knee pain could not be predicted with any clinical or radiographic parameter studied. On the basis of these results, it seems likely that postoperative anterior knee pain is related either to the component design or to the details of the surgical technique, such as component rotation, rather than to whether or not the patella is resurfaced.

Epidermal growth factor regulation of equine glycoprotein hormone alpha subunit expression in trophoblast cells

Primates and equids are the only species known to express the placental glycoprotein hormone, chorionic gonadotropin (CG), a heterodimeric glycoprotein composed of an alpha subunit linked to a hormone-specific beta subunit. The regulatory mechanisms involved in the induction of equine glycoprotein alpha subunit gene expression have not been identified. Epidermal growth factor (EGF) receptor is known to transduce signals that alter a number of different cellular functions (cell proliferation, differentiation, hormone secretion, and gene regulation). In the present study, we investigated the regulation of the equine alpha subunit gene by EGF in trophoblasts. We found that 2800 base pairs of 5' flanking sequence from the equine alpha subunit promoter is sufficient for basal expression in human choriocarcinoma cells. Epidermal growth factor and phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C (PKC), increased transcriptional activity of the equine alpha subunit promoter (-2800/+21). These responses were blocked by pretreatment with bisindolylmaleimide-I, an inhibitor of PKC, suggesting an involvement of this pathway downstream of EGF. In addition, PD98059, an inhibitor of the extracellular signal-regulated kinase (ERK) pathway, completely blocked activation of the equine alpha promoter by PMA, suggesting that mitogen-activated protein kinase (MAPK) cascade was involved downstream of the PKC pathway. In conclusion, the EGF/PKC/MAPK pathway regulates equine glycoprotein alpha subunit gene expression through a distinct regulatory region (-2300 to -1900) in trophoblasts, while essential elements for basal expression appear to exist within the -2800 to -1900 region of the promoter.

Syringomyelia and developmental scoliosis

We attempted to characterize the signs and symptoms of patients presenting with scoliosis as a manifestation of occult syringomyelia, and to determine the effect of syrinx decompression on the deformity and neurologic deficits. This study represented 21 patients treated from 1981 through 1991 at the authors' institution. All patients with occult syringomyelia and no other central nervous system lesions underwent decompression of the syrinx, with improvement in neurologic signs and symptoms. Three of the four with scoliosis that were not treated by arthrodesis showed improvement of their deformity at an average follow-up of 35 months. Three of five patients with myelodysplasia, occult syringomyelia, and scoliosis not previously treated with spinal arthrodesis showed stabilization or improvement of their deformity at an average follow-up of 21 months. We conclude that syringomyelia is associated with a high incidence of developmental scoliosis, and that decompression of the syrinx leads to improvement in, or stabilization of, the majority of scoliotic curves, or postpones the need for fusion.

Effects of estradiol-17beta administration on steady-state messenger ribonucleic acid (MRNA) encoding equine alpha and LH/CGbeta subunits in pituitaries of ovariectomized pony mares

The process of sexual recrudescence in the springtime in mares is characterized by renewal of follicular growth and acquisition of steroidogenic competence. Concomitant with renewal of follicular steroidogenesis is re-establishment of LH biosynthesis and secretion. Research results from our laboratory indicate that increased estradiol and LH secretion occur in close temporal association before the first ovulation of the year. Therefore, the hypothesis tested in this experiment was that estrogen administration to ovariectomized pony mares during the equivalent time of early vernal transition would enhance LH biosynthesis as monitored by messenger ribonucleic acid (mRNA) encoding for the pituitary subunits of LH (alpha and LH/CGbeta). Mares were administered either sesame oil vehicle control, or estradiol (5 mg i.m. twice daily in sesame oil) for 3, 6 or 9 days, beginning on February 2. The pituitary glands were harvested, and examined for LH subunit mRNA by Northern Blot and slot blot analysis. There was a significant increase in LH secretion after 6 days of estradiol secretion compared with control vehicle administration. Similarly, there was a significant increase in both alpha and LH/CGbeta subunit mRNA when estradiol was administered for 9 days. These data indicate that estrogen stimulates LH subunit formation in mares during early equivalent vernal transition. These data do not, however, discriminate between a direct pituitary effect of estrogen, and a hypothalamic effect. Whether the surge of estradiol just prior to the first ovulation of the year is essential for the renewed biosynthesis of LH subunits cannot be determined from these data. However an important role of estrogen in the final stages of sexual recrudescence is indicated.

Management of ankle sprains

Without adequate care, acute ankle trauma can result in chronic joint instability. Use of a standardized protocol enhances the management of ankle sprains. In patients with grades I or II sprains, emphasis should be placed on accurate diagnosis, early use of RICE (rest, ice, compression and elevation), maintenance of range of motion and use of an ankle support. Sprains with complete ligament [corrected] tears (grade III) may require surgical intervention. Although early motion and mobility are recommended, ligamentous strength does not return until months after an ankle sprain.

Placental lactogen-I gene activation in differentiating trophoblast cells: extrinsic and intrinsic regulation involving mitogen-activated protein kinase signaling pathways

Trophoblast giant cells are one of the primary endocrine cell types of the rodent placenta. Placental lactogen-I (PL-I) is the initial prolactin (PRL) family member expressed as trophoblast giant cells differentiate. In this report, we use the Rcho-1 trophoblast cell line as a model for studying the regulation of PL-I gene expression during trophoblast giant cell differentiation. Evidence is provided for trophoblast cell expression of epidermal growth factor receptor (EGFR), ErbB2, fibroblast growth factor receptor 1 (FGFR1), transforming growth factor-alpha, and heparin-binding EGF. EGF and FGF-2 stimulated PL-I mRNA and protein accumulation and PL-I promoter activity in a concentration-dependent manner. These latter growth factor actions on PL-I promoter activities were specifically inhibited by cotransfection with dominant negative constructs for EGFR and FGFRs respectively. Utilization of the mitogen-activated protein kinase (MAPK) pathway by EGF and FGF-2 in trophoblast cells was demonstrated by growth factor stimulation of a Gal4 DNA binding/Elk1 transactivational domain fusion construct, and more specifically by activation of extracellular signal regulated kinase and p38 MAPK. PL-I gene activation was also sensitive to disruption of MAPK and activation protein-1 (AP-1) signaling pathways. In conclusion, autocrine/paracrine pathways involving EGFR and FGFR1, MAPK and AP-1 are shown to participate in the regulation of the PL-I gene in differentiating trophoblast cells.

P-glycoprotein levels predict poor outcome in patients with osteosarcoma

To evaluate the relationship between the expression of P-glycoprotein by osteosarcomas and the rate of metastasis and death, a retrospective review of 172 patients who were diagnosed with osteosarcoma between 1987 and 1992 was performed. Forty patients had P-glycoprotein levels available. The majority of the osteosarcomas were Stage II-B (33 patients), with the remaining seven being Stage III. Tumor sites included 25 femurs, seven humeri, five tibias, and one each of pelvis, radius, and fibula. The patients with Stage III disease at presentation were treated differently from the time of diagnosis and therefore, these seven patients with Stage III osteosarcoma were excluded from additional analyses. The expression of P-glycoprotein by cultured tumor cells from biopsy specimens was determined using immunofluorescent microscopy. In the 33 patients with Stage IIB osteosarcoma with detectable P-glycoprotein, 67% (10 of 15) had metastases develop as compared with 28% (five of 18) of patients with undetectable P-glycoprotein. Similarly, 53% (eight of 15) of patients with tumors expressing P-glycoprotein died of disease compared with 11% (two of 18) with no detectable P-glycoprotein. Expression of P-glycoprotein by tumor cells seems to be associated with an estimated ninefold increase in the odds of death and a fivefold increase in the odds of metastases in patients with Stage IIB osteosarcoma. Kaplan-Meier survivorship analysis revealed that patients with detectable P-glycoprotein fared worse in terms of survival time and metastasis-free survival. Adjusting for covariates in the Cox proportional hazards model, expression of P-glycoprotein and its level were significantly predictive of time to death in patients with Stage IIB osteosarcoma.

Patellar resurfacing in total knee arthroplasty

Whether or not to resurface the patella when performing a primary total knee arthroplasty remains an open question. A number of recent studies have added new information relevant to this controversy. Anatomic studies show that there is normally substantial variability in the anatomy of the trochlear groove. Implanting a femoral component therefore results in a change in the surface topography of the knee in a high percentage of cases. Even though a number of intraoperative techniques have been described in an attempt to accurately reproduce femoral and tibial component rotation, studies of the application of these techniques reveal that component malpositioning or malrotation of a measurable degree occurs in 10% to 30% of cases, depending on the surgical technique and landmarks used. There has been substantial change in the design of both femoral and patellar components in recent years. Even with current designs, biomechanical studies indicate that some degree of change in kinematics and contact stresses occurs following total knee arthroplasty. However, the results of clinical studies have been extremely variable, with most showing either no difference or very little difference between resurfaced and nonresurfaced patellae in osteoarthritic knees. The decision to resurface the patella or not must be individualized on the basis of the surgeon's training and experience and an intraoperative assessment of the patellofemoral articulation.

Patient compliance and satisfaction with mechanical devices for preventing deep venous thrombosis after joint replacement

A consecutive series of patients having total joint arthroplasty at a single university hospital were sequentially treated with two mechanical devices for prevention of deep venous thrombosis (DVT). The first 104 patients (group 1) wore thigh-high sequential compression device (SCD). The next 120 patients (group 2) wore a foot pump. Daily documentation of hourly compliance with each respective device was recorded until discharge. A patient satisfaction questionnaire was also obtained. Patient understanding about the devices' function aided compliance (73% compliance in group 1, and 77% in group 2). The satisfaction questionnaire revealed significantly greater satisfaction in group 2 (73%) versus group 1 (55%). Of a subgroup of 35 patients who had used both devices, 24 preferred the foot pump, 7 the SCD, and 4 had no preference. This study showed a higher degree of compliance and satisfaction for foot pumps as prophylaxis against DVT.

Improving readiness and fitness of the active military force through occupational medicine tenets

The United States Military deploys its forces with minimal lead time. These forces must be medically qualified and physically fit for any locale and mission scenario. Historically, up to half of the force identified for deployment at any given time were not medically qualified. Matching individuals to specific occupations using validated medical and physical performance standards is an occupational medicine tenet that increases the effectiveness and efficiency of the workforce. To establish a cost-effective, valid medical program ensuring a fit and ready force, the military must: (1) develop validated physical fitness/occupational standards; (2) consolidate one fitness standard for males/females on the basis of workload requirements; (3) eliminate differing age standards; (4) provide statistically relevant medical screening, testing for health maintenance, and fitness for duty; and (5) mandate one joint medical standard for all military services.

Distinct regulatory regions from the prolactin-like protein C variant promoter direct trophoblast giant cell versus spongiotrophoblast cell-specific expression

PRL-like protein C variant (PLP-Cv) is a newly identified member of the PRL family. PLP-Cv is specifically expressed in the chorioallantoic placenta by two distinct cell populations: trophoblast giant cells and spongiotrophoblast cells. To gain some insight regarding the control of PLP-Cv gene expression and the regulatory factors controlling trophoblast giant cell and spongiotrophoblast cell lineages, we have initiated a structural and functional analysis of the PLP-Cv promoter. The activities of a series of PLP-Cv promoter constructs, ranging in size from 4.5 kb to 50 bp, ligated to a luciferase reporter have been assessed in the Rcho-1 trophoblast cell line (restricted to trophoblast giant cell differentiation) and in a primary spongiotrophoblast cell culture system after transient transfection. PLP-Cv promoter constructs containing 4.5 kb to 149 bp of 5'-flanking DNA possessed full activity in the trophoblast giant cell model. A region located between -149 and -124 bp upstream of the PLP-Cv transcription start site was found to be essential for activation of the PLP-Cv promoter. Spongiotrophoblast cells required additional PLP-Cv 5'-flanking DNA for full activity. A region located between -2518 and -2242 bp upstream of the PLP-Cv transcription start site significantly enhanced PLP-Cv promoter in spongiotrophoblast cells. In conclusion, mechanisms underlying the activation of the PLP-Cv promoter are different in trophoblast giant cells vs. spongiotrophoblast cells.

Gonadotropin-releasing hormone activates the equine luteinizing hormone beta promoter through a protein kinase C/mitogen-activated protein kinase pathway

GnRH regulation of LH secretion is well understood and involves Ca(2+) mobilization. However, the mechanism by which GnRH activates transcription of the LHbeta gene is controversial. GnRH is known to elevate intracellular calcium and activate the protein kinase C (PKC) pathway. The present study evaluated the pathway(s) involved in GnRH induction of LHbeta transcription. We have previously reported that the equine LHbeta (eLHbeta -448/+60) promoter is active in alphaT3-1 cells. Therefore, we created a clonal, stably transfected alphaT3-1 gonadotroph cell line harboring the eLHbeta promoter (-448/+60) fused to the luciferase reporter gene. Administration of a GnRH agonist resulted in induction of promoter activity that was completely inhibited by the antagonist antide. Various calcium-affecting drugs had no effect on the promoter. Administration of phorbol 12-myristate 13-acetate (PMA) elicited an activation similar to, albeit lower than, that with GnRH. Down-regulation or pharmacological inhibition of PKC completely blocked PMA's induction of the promoter, while GnRH induction was only partly attenuated. Treatment with the mitogen-activated protein kinase (MAPK) kinase inhibitor, PD98059, completely inhibited the activation of eLHbeta by PMA but only partly diminished GnRH's induction. Expression of the transcription factor, early growth response protein 1 (Egr1), correlated completely with activation of MAPK, suggesting that Egr1 is the factor through which PKC/MAPK acts. Our data suggest that GnRH induces activity of the eLHbeta promoter by activating a signal transduction cascade involving PKC-MAPK-Egr1 but that has no significant requirement for calcium.

The equine luteinizing hormone beta-subunit promoter contains two functional steroidogenic factor-1 response elements

The requirements for basal expression of the LH beta-subunit promoter in pituitary gonadotropes are largely unknown. We have used the equine (e) LHbeta subunit promoter as a model to unravel the combinatorial code required for gonadotrope expression. Through the use of 5'-deletion mutagenesis, a region between -185 and -100 of the eLHbeta promoter was shown to play a critical role in maintaining basal promoter activity in alphaT3-1 and LbetaT2 cells. This region encompasses the steroidogenic factor-1 (SF-1) binding site that has been reported to have a functional role in expression of the LHbeta promoter in other species. We have also identified an additional SF-1 site at -55 to -48. Binding of SF-1 to both sites was confirmed by electrophoretic mobility shift assays. Mutations within these sites, either individually or in combination, did not attenuate basal activity of the eLHbeta promoter in alphaT3-1 cells, but did diminish promoter activity in LbetaT2 cells. Interestingly, cotransfection with an expression vector encoding SF-1 induced eLHbeta promoter activity, and this induction was abrogated by mutations within the SF-1 sites in alphaT3-1 cells. Block replacement mutagenesis was performed on the -185/-100 region of the eLHbeta promoter to identify DNA response elements responsible for maintaining basal promoter activity. From this analysis, two regions emerged as being important: a distal 31-bp segment (-181 to -150) and an element located immediately 3' to the distal SF-1 site (-119 to -106). It is hypothesized that these two regions as well as the SF-1 sites represent regulatory elements that contribute to a combinatorial code involved in targeting expression of the eLHbeta promoter to gonadotropes.

Early growth response protein 1 binds to the luteinizing hormone-beta promoter and mediates gonadotropin-releasing hormone-stimulated gene expression

The hypothalamic neuropeptide, GnRH, regulates the synthesis and secretion of LH from pituitary gonadotropes. Furthermore, it has been shown that the LH beta-subunit gene is regulated by the transcription factors steroidogenic factor-1 (SF-1) and early growth response protein 1 (Egr1) in vitro and in vivo. The present study investigated the roles played by Egr1 and SF-1 in regulating activity of the equine LH beta-subunit promoter in the gonadotrope cell line, alpha T3-1, and the importance of these factors and cis-acting elements in regulation of the promoter by GnRH. All four members of the Egr family were found to induce activity of the equine promoter. The region responsible for induction by Egr was localized to the proximal 185 bp of the promoter, which contained two Egr response elements. Coexpression of Egr1 and SF-1 led to a synergistic activation of the equine (e)LH beta promoter. Mutation of any of the Egr or SF-1 response elements attenuated this synergism. Endogenous expression of Egr1 in alpha T3-1 cells was not detectable under basal conditions, but was rapidly induced after GnRH stimulation. Reexamination of the promoter constructs harboring mutant Egr or SF-1 sites indicated that these sites were required for GnRH induction. In fact, mutation of both Egr sites within the eLH beta promoter completely attenuated its induction by GnRH. Thus, GnRH induces expression of Egr1, which subsequently activates the eLH beta promoter. Finally, GnRH not only induced expression of Egr1, but also its corepressor, NGFI-A (Egr1) binding protein (Nab1), which can repress Egr1- induced transcription of the eLH beta promoter.

Decreasing length of hospital stay in treatment of osteoid osteoma

Ninety-eight operative procedures were performed for treatment of osteoid osteoma since 1978 at the authors' institution. During these years there was a progressive decrease in the length of hospital stay, decreasing from a mean of 6.8 days between 1978 and 1980 to 2.6 days between 1994 and 1996. Factors that influenced the length of stay after a surgical procedure include patient age, lesion location, choice of procedure, and surgeon. However, the decline in length of stay with time is independent of these factors, and antedates the era of managed care. Increased reliance on more conservative surgical procedures has markedly diminished the length of hospital stay required in the care of these patients.

Use of an osteoinductive biomaterial (rhOP-1) in healing large segmental bone defects

OBJECTIVE

To assess the radiographic, histologic, and mechanical characteristics of new bone formation in large segmental bone defects treated with a new osteoconductive material, recombinant human osteogenic protein-1 (rhOP-1).

DESIGN

In vivo animal study.

INTERVENTION

Sixteen dogs (thirty-two limbs) with an ulna segmental defect (2.5 centimeters) were randomized to three treatment groups: rhOP-1, collagen alone, and no implant.

MAIN OUTCOME MEASUREMENTS

Radiographic evidence of defect healing, mechanical testing (torsional strength) as compared with thirty-one control intact dog ulnas, and histologic analysis.

RESULTS

At twelve weeks, complete radiographic healing was observed in twenty-five of twenty-eight defects (89 percent) treated with rhOP-1. The mechanical strength of the rhOP-1-treated defects at twelve weeks was 65 percent of that of intact ulnas. Histologic analysis revealed that defects treated with rhOP-1 were bridged with lamellar and woven bone that was in continuity with the host bone.

CONCLUSIONS

The results indicate that osteoinductive materials, which have the ability to quickly fill and heal large defects, may have advantages over osteoconductive materials, which are typically used to fill smaller non-load-bearing bone voids.

Percutaneous radiofrequency coagulation of osteoid osteoma compared with operative treatment

Osteoid osteoma, a benign bone tumor, has traditionally been treated with operative excision. A recently developed method for percutaneous ablation of the tumor has been proposed as an alternative to operative treatment. The relative outcomes of the two approaches to treatment have not previously been compared, to our knowledge. The rates of recurrence and of persistent symptoms were compared in a consecutive series of eighty-seven patients who were managed with operative excision and thirty-eight patients who were managed with percutaneous ablation with radiofrequency. Patients who had a spinal lesion were excluded. The minimum duration of follow-up was two years. There was a recurrence, defined as the need for subsequent intervention, after operative treatment in six (9 per cent) of sixty-eight patients who had been managed for a primary lesion and in two of nineteen who had been managed for a recurrent lesion. The average length of the hospital stay was 4.7 days for the patients who had a primary lesion and 5.1 days for those who had a recurrent lesion. There was a recurrence after percutaneous treatment in four (12 per cent) of thirty-three patients who had been managed for a primary lesion and in none of five who had been managed for a recurrent lesion. The average length of the hospital stay was 0.2 day for these thirty-eight patients. With the numbers available, we could detect no significant difference between the two treatments with regard to the rate of recurrence. The rate of persistent symptoms (that is, symptoms that did not necessitate additional treatment) was greater than the rate of recurrence. According to responses to a questionnaire, eight (30 per cent) of twenty-seven patients had persistent symptoms after operative treatment and six (23 per cent) of twenty-six patients had persistent symptoms after percutaneous treatment with radiofrequency. Two patients had complications after operative excision, necessitating a total of five additional operations. There were no complications associated with the percutaneous method. The results of the present study suggest that percutaneous ablation with radiofrequency is essentially equivalent to operative excision for the treatment of an osteoid osteoma in an extremity. The percutaneous method is preferred for the treatment of extraspinal osteoid osteoma because it generally does not necessitate hospitalization, it has not been associated with complications, and it is associated with a rapid convalescence.

The Coventry Award. The value of preoperative aspiration before total knee revision

The value of routine aspiration of a symptomatic total knee replacement before reoperation was evaluated. The study group consisted of a consecutive series of 69 knees in 67 patients in which preoperative aspiration was performed. All aspirations were performed on an outpatient basis in a clinic setting. Local anesthetics and saline washings were not used. Twenty knees were determined to be infected and 49 knees were not infected. Preoperative aspiration had an overall sensitivity of 55%, specificity of 96%, accuracy of 84%, positive predictive value of 85%, and negative predictive value of 84%. Sixteen patients were taking antibiotics at the time of referral including 12 of 20 (60%) who had infected knees. Seven of these 12 (58%) had no growth on their initial knee aspiration. Four of these had their knees reaspirated at a later date because of a high index of suspicion for infection and the subsequent aspiration revealed the infecting organism in all four cases. Two of the remaining three patients had signs of sepsis develop and reaspiration was not performed because immediate reoperation was indicated clinically. The initial aspiration on the third patient was performed after antibiotic therapy was discontinued for 4 weeks and a repeat aspiration was not deemed necessary. When the results of the reaspirations are included, the overall aspiration results improved to a sensitivity of 75%, specificity of 96%, and accuracy of 90%. The results of the study support the use of routine preoperative aspiration before total knee revision. Previous antibiotic use increases the risk of a false negative result, and reaspiration at a later date can be expected to significantly improve the value of this test in such cases.

Characterization of the equine glycoprotein hormone alpha-subunit gene reveals divergence in the mechanism of pituitary and placental expression

The equine glycoprotein hormone alpha-subunit gene is expressed in both pituitary and placenta, unlike that of all other nonprimate mammals studied, in which expression is limited to pituitary. Previous studies of the 5'-flanking region of the equine alpha-subunit promoter have revealed unique characteristics as well as similarities with the human alpha-subunit promoter, which demonstrates a similar pattern of tissue-specific expression. We have cloned and sequenced the equine alpha-subunit gene and have used tissue culture systems and transgenic mice to characterize its expression. Unlike the human promoter, the cloned equine alpha-subunit promoter failed to direct trophoblast-specific expression in either tissue culture or transgenic mouse models, suggesting an entirely different mechanism for expression. In contrast, the equine alpha-subunit promoter was able to direct gonadotroph expression in both tissue culture and transgenic mouse models. In alphaT3-1 cells, 550 base pair (bp) was sufficient for expression. This expression involves promoter elements identified in other species as playing a role in gonadotroph expression, but mutation of these elements reveals differences in their relative contributions to promoter activity. In mice, 2800 bp of 5'-flanking sequence allowed specific expression in gonadotrophs but not in thyrotrophs or placenta. The pattern of estrogen regulation observed in transgenic mice matched neither the repression that has been observed with human and bovine alpha-subunit promoters in transgenic mice nor the stimulation in mRNA levels reported in mares, suggesting a unique mechanism that is not recapitulated in the transgenic model. Thus the equine alpha-subunit promoter uses a combination of conserved and unique features of gene regulation to direct its pattern of tissue-specific expression.

Resurfacing of the patella in total knee arthroplasty. A prospective, randomized, double-blind study

During a two-year period, eighty-nine patients who were scheduled to have a total knee arthroplasty for the treatment of degenerative osteoarthrosis were randomly assigned to one of two groups: resurfacing of the patella or retention of the patella. All patients received the same posterior cruciate-sparing prosthesis, and all operations were performed by, or under the direct supervision of, one of us. Three patients died in the early postoperative period. The remaining eighty-six patients (118 knees; fifty-eight that had had resurfacing of the patella and sixty that had not) formed the study group. They were followed for a mean of thirty months (range, twenty-four to forty-four months). Evaluation was performed with use of the clinical scoring system of The Knee Society, a patient-satisfaction questionnaire, specific questions regarding patellofemoral symptoms and function, and radiographs. All clinical evaluations were performed by the same research nurse, without the involvement of a physician, in a blinded manner (neither the nurse nor the patient had knowledge of whether the patella had been resurfaced). Preoperatively, the mean Knee Society score, on a scale ranging from 0 to 200 points, was 89.7 points (range, 33 to 132 points); postoperatively, this score improved to a mean of 172.7 points (range, 98 to 200 points). With the numbers available for study, we could detect no significant difference between the knees that had had patellar resurfacing and those that had not with regard to the over-all score (p = 0.63), the subscore for pain (p = 0.56), or the subscore for function (p = 0.77). We also could detect no difference between the treatment groups, with the numbers available, with regard to patient satisfaction or the responses to questions involving the function of the patellofemoral joint, including the ability to exit from an automobile, to rise from a chair, and to climb stairs. Thirty-two patients had bilateral total knee replacement with resurfacing of the patella in one knee and retention of the patella in the other. These patients expressed no clear preference for either knee. Eight (13 per cent) of the sixty knees that had not had resurfacing were painful anteriorly compared with four (7 per cent) of the fifty-eight that had; this was not a significant difference (p = 0.38), with the numbers available. The anterior pain that was noted postoperatively was predominantly of new onset; it had not been observed preoperatively in three of the four knees that had had resurfacing or in four of the eight that had not. No additional treatment options were offered to the patients who had anterior pain in the knee after resurfacing. However, six (10 per cent) of the sixty knees that had not had resurfacing had it subsequently, because of anterior pain in the knee, after the twelfth postoperative month (range, fifteen to thirty-nine months). The pain decreased in four of these knees. Thus, total knee arthroplasty with retention of the patella yielded clinical results that were comparable with those after total knee arthroplasty with patellar resurfacing, but it was associated with a 10 per cent prevalence of the need for subsequent resurfacing. The prevalence of anterior pain after total knee arthroplasty was not influenced by whether or not the patella had been resurfaced. The postoperative clinical scores, the postoperative development of anterior pain, and the need for subsequent resurfacing were not predicted by the presence of preoperative anterior pain, obesity, or the grade of chondromalacia observed intraoperatively. Because of the short duration of follow-up, these results should be considered preliminary. Additional follow-up is planned.

Pyomyositis with toxic shock syndrome presenting as back pain and fever: a case report and literature review

Pyomyositis is an uncommon cause of musculoskeletal pain in children and adolescents living in temperate climates. Toxic shock syndrome is a life-threatening potential complication of pyomyositis. We report a case of acute hematogenous pyomyositis, complicated by toxic shock syndrome, and review the pertinent literature.

Analysis and comparison of operator-specific outcomes in interventional cardiology. From a multicenter database of 4860 quality-controlled procedures

BACKGROUND

Medical consumers are increasingly requesting methods to discriminate among the results of different providers. Standards for appropriate modeling, risk adjustment, and evaluation ("scorecarding") in this setting are not well developed, although such evaluation is being performed by the medical insurance industry and by several states in the United States. Our objectives were to develop and examine clinically meaningful methodology for assessing the operator-specific results for percutaneous coronary revascularization.

METHODS AND RESULTS

From a multicenter database of patients treated since January 1, 1990, we used training and validation samples (n = 4860) to develop several models for risk adjustment and applied them to 38 providers performing 25 to 523 procedures in the database. Models were developed using multivariable logistic regression techniques for combinations of the end points of death, myocardial infarction, bypass surgery, and procedural success. Models were evaluated for predictive accuracy by using receiver operating characteristic (ROC) analysis, for the capacity to discriminate between superior and inferior provider outcomes, and for subjectivity and concordance. Major complications occurred in 3.6% of patients. The area under the ROC curve (with perfect discriminatory accuracy, area = 1.0; with no apparent accuracy, area = 0.5) in the validation sample, and frequency of identification of operators with outcomes outside the 95% CI for the outcome in question for the models were for death, 0.85 and 7.9%; for death, Q-wave infarction, and bypass surgery, 0.77 and 13.2%; for death, all infarction, and bypass surgery, 0.66 and 10.5%; and for procedural success, 0.76 and 23.7%. For the models as a group, identification of outliers was inversely related to provider volume (P = .05). Models evaluating non-Q-wave infarction or requiring measurement of percent diameter stenosis were identified as being most susceptible to provider manipulation.

CONCLUSIONS

For percutaneous coronary revascularization, modeling to discriminate between provider outcomes is limited by the low incidence of major adverse events, subjectivity or susceptibility to manipulation of more frequently occurring adverse events, the generally modest predictive capacity of the models, and the low volume of individual provider treatments. Modeling will be most useful in the identification of providers with extremely poor outcomes and for discrimination between providers with very large procedural volume. Until improved understanding of the biological and mechanical correlates of major complications allows the development of more predictive models, interpretation of the results of scorecarding, particularly for low-volume providers, should be made with caution.

Length of hospital stay and complications after percutaneous transluminal coronary angioplasty. Clinical and procedural predictors. Heparin Registry Investigators

BACKGROUND

Although several studies have established that the complications of percutaneous transluminal coronary angioplasty (PTCA) are related to clinical and angiographic variables such as advanced age and lesion complexity, it is uncertain whether the use of hospital resources after PTCA also depends on the same baseline variables. The purpose of this study was to identify the factors responsible for prolonged hospital stay after PTCA.

METHODS AND RESULTS

The study cohort included 591 consecutive patients undergoing conventional balloon angioplasty at nine medical centers in North America. Major or minor complications occurred in 91 patients (15.4%) and were observed to be related to several baseline characteristics, including unstable angina, multivessel coronary artery disease, patient age, and lesion complexity. Compared with a median length of hospital stay of 2.0 days after PTCA (25th, 75th percentiles: 2.0, 4.0) for the entire cohort of patients, the length of stay was increased in patients with unstable angina (3.0 days [2.0, 5.0]; P = .002), multivessel coronary artery disease (3.0 [2.0, 5.5]; P = .001), age > 65 years (3.0 [2.0, 5.5]; P = .02), complex lesions (3.0 [2.0, 6.0]; P = .001), and filling defects (6.0 [2.0, 11.0]; P < .001). The length of stay was more strikingly increased, however, in patients who experienced major or minor PTCA complications, such as emergency bypass surgery (9.0 days [8.0, 18.0]; P < .001), Q-wave or non-Q-wave myocardial infarction (8.0 [6.0, 15.5]; P < .001), transfusion unrelated to bypass surgery (8.0 [4.0, 12.0]; P < .001), or abrupt vessel closure (6.0 [3.0, 10.5]; P < .001). On stepwise multiple linear regression, PTCA complications appeared to be the strongest predictors of length of hospital stay (all P < .001) and overwhelmed the weaker relation between length of stay and several individual baseline variables. Inclusion of a composite clinical risk score (reflecting the presence of unstable angina, multivessel disease, advanced age, complex lesions, or filling defects) in the regression model confirmed that patients with several high-risk baseline variables had a significant increase in length of stay after PTCA (P = .003), but PTCA complications remained the strongest predictors of length of stay.

CONCLUSIONS

Although PTCA complications were correlated with baseline variables such as unstable angina, multivessel disease, advanced age, complex lesions, and filling defects, excess length of stay after PTCA was most strongly influenced by the development of minor and major PTCA complications. Because patients with several baseline risk factors experienced significantly prolonged hospitalizations, improved selection of patients may contribute to reductions in length of stay after PTCA. A greater reduction in resource use after PTCA, however, would be expected from developing new treatments to decrease PTCA complications rather than limiting the access of patients with unstable angina, advanced age, or complex lesions to PTCA.

Effect of recombinant human osteogenic protein-1 on healing of segmental defects in non-human primates

The effect of recombinant human osteogenic protein-1 on the healing of segmental bone defects was studied in twenty-eight African green monkeys (Cercopithecus aethiops). A 2.0-centimeter osteoperiosteal defect was created in the middle of the ulnar shaft in fourteen animals and in the diaphysis of the tibia in the other fourteen. The ulnar defect was filled with an implant consisting of 1000 micrograms of recombinant human osteogenic protein-1 in 400 milligrams of bovine bone-collagen carrier in six animals, with collagen carrier alone in two animals, and with autogenous cancellous bone graft from the contralateral tibia and femur in six animals. The tibial defect was filled with 250, 500 (two tibiae), 1000, or 2000 micrograms of recombinant human osteogenic protein-1 in 400 milligrams of collagen carrier in five animals, with collagen carrier alone in one animal, and with autogenous cancellous bone graft in six animals; in the two remaining animals (controls), the tibial defect was left unfilled. The tibial defects were stabilized with an intramedullary Steinmann pin. All animals were killed at twenty weeks postoperatively. Healing of the defects was evaluated with biweekly radiographs, with histological examination, and with mechanical testing. Radiographically, all of the defects that had been treated with recombinant human osteogenic protein-1 exhibited new-bone formation, but they differed in the degree of healing and remodeling. Five of the six ulnae treated with recombinant human osteogenic protein-1 and four of the five tibiae treated with this substance exhibited complete healing at six to eight weeks, with bridging of the defect by new bone first observed at four weeks. The two unhealed defects both exhibited new-bone formation but incomplete union, which precluded mechanical testing. No defect that had been filled with collagen carrier or that had been left unfilled exhibited any signs of healing or major new-bone formation. None of the six ulnae that had been filled with autogenous bone graft exhibited complete healing, compared with five of the six tibiae that had been so treated. Histological evaluation of the defects treated with recombinant human osteogenic protein-1 revealed the formation of new cortices with areas of woven and lamellar bone and normal-appearing marrow elements at twenty weeks postoperatively. The tibial defects that had been treated with autogenous bone graft had a similar appearance. All control ulnar and tibial defects and all ulnar defects that had been treated with autogenous bone graft had fibrous union with little new-bone formation.(ABSTRACT TRUNCATED AT 400 WORDS)

Increasing concentrations of 17 beta-estradiol has differential effects on secretion of luteinizing hormone and follicle-stimulating hormone and amounts of mRNA for gonadotropin subunits during the follicular phase of the bovine estrous cycle

The hypothesis tested was that 17 beta-estradiol (E2) would increase amounts of mRNA for alpha, LH beta, and FSH beta subunits during the follicular phase of the estrous cycle prior to the preovulatory surge of gonadotropins in cows. On Day 16 (Day 0 = estrus) of the estrous cycle, all cows were treated with prostaglandin F2 alpha (PGF2 alpha). Cows served as intact controls (CONT, n = 4) were ovariectomized (OVX, n = 5), or were ovariectomized and administered E2 (OVXE, n = 6) in increasing doses starting at the time of treatment with PGF2 alpha. Cows were bled for 6 h before and for 40 h after PGF2 alpha treatment to characterize pulsatile secretion of LH and FSH. Forty hours after PGF2 alpha treatment, pituitaries were collected for evaluation of amounts of mRNA for alpha, LH beta, and FSH beta subunits. Amplitude of LH pulses was greater (p < 0.05) in cows from the OVXE than from the CONT group. Concentrations of FSH were greater in cows from both the OVXE and OVX (p < 0.01) groups than from the CONT group. Amounts of mRNA for alpha and FSH beta subunits were greater (p < 0.01) in pituitaries of cows from the OVX than from the CONT or OVXE groups. Amounts of mRNA for LH beta subunit in pituitaries of cows from the OVX group tended to be greater (p < 0.08) than from the CONT group. Cows in the OVXE group tended (p < 0.08) to have greater amounts of mRNA for FSH beta subunit than did CONT cows.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of 17 beta-estradiol on distribution of pituitary isoforms of luteinizing hormone and follicle-stimulating hormone during the follicular phase of the bovine estrous cycle

The objective of this study was to examine the influence of 17 beta-estradiol (E2) on distribution of LH and FSH isoforms during the follicular phase of the bovine estrous cycle prior to the preovulatory surges of LH and FSH. On Day 16 of the estrous cycle (Day 0 = estrus), intact controls (CONT; n = 4) were treated with prostaglandin F2 alpha (PGF2 alpha) to induce luteal regression and initiation of the follicular phase. Other cows were also treated with PGF2 alpha and either ovariectomized (OVX; n = 5) or ovariectomized and given E2 implants (OVXE; n = 6) to mimic the pattern of increasing E2 concentrations during the follicular phase of the estrous cycle. Pituitaries were collected 40 h after treatment with PGF 2 alpha or ovariectomy (0 h). Aliquots of pituitary extracts were chromatofocused on pH 10.5-4.0 gradients. The LH resolved into thirteen isoforms (designated A-L and S, beginning with the most basic form) while FSH resolved into nine isoforms (designated I-IX, beginning with the most basic form). The percentage of LH as isoform F (elution pH = 9.32 +/- 0.01) was greater (p < 0.05) in the OVX group (48.5%) than in the OVXE group (45.0%). LH isoforms I (elution pH = 6.98 +/- 0.01) and J (elution pH = 6.48 +/- 0.01) were more abundant (p < 0.05) in cows from the OVXE (2.3 and 5.8%, respectively) than the OVX group (1.4 and 3.7%, respectively). Distribution of LH isoforms in cows from the three groups did not differ (p > 0.10).(ABSTRACT TRUNCATED AT 250 WORDS)

The relation of clinical outcome to dissection and thrombus formation during coronary angioplasty. Heparin Registry Investigators

BACKGROUND

Although the development of thrombus or dissection during percutaneous transluminal coronary angioplasty (PTCA) increases the risk of abrupt vessel closure, the magnitude of the effect is difficult to define.

OBJECTIVE

The aim of the study was to determine prospectively the effect of the development of thrombus or dissection on PTCA procedural outcome.

METHODS

Data from 591 consecutive angioplasty procedures involving 756 lesions at 9 clinical centers were included in a prospective registry with a core angiographic laboratory.

RESULTS

Clinical success (defined as < 50% stenosis of all target lesions assessed in a core angiographic laboratory, with no major complications of death, Q wave or non-Q wave myocardial infarction or emergency CABG) was achieved in 497 patients (84%). Major complications occurred in 45 (7.6%). Abrupt vessel closure, including both established closure (TIMI grade 0 or I flow) and impending closure (> 50% stenosis, TIMI grade 0-2 flow, plus use of additional interventions) occurred in 65 patients (11%). Angiographically visible dissections developed in 40% of lesions; more severe grades of dissection were associated with reduced success rates, and increased incidence of and abrupt vessel closure and major complication. Angiographic evidence of thrombus (filling defects) developed in 12.3% of lesions; the presence of thrombus was associated with significantly lower procedural success (61% vs. 86%) and significantly higher rates of abrupt vessel closure (28% vs 7%) and major complications (24% vs. 6%). With multivariable analysis, thrombus was identified as an independent predictor of procedural success, abrupt vessel closure, and major complications.

CONCLUSIONS

The development of severe dissections or thrombus following PTCA is associated with significantly lower procedural success rates and higher rates of abrupt vessel closure and major complications. Patients who develop severe dissection or thrombus may be appropriate candidates for more aggressive forms of therapy.

Chondroblastoma of the patella presenting as knee pain in an adolescent

We report a case of chondroblastoma of the patella, associated with an aneurysmal bone cyst and pathologic fracture, that presented as knee pain in a 13-year-old girl. This case is the fifth case in the literature that associates patellar chondroblastoma with fracture, which should probably be regarded as a significant feature of this lesion.

The proximal promoter of the bovine luteinizing hormone beta-subunit gene confers gonadotrope-specific expression and regulation by gonadotropin-releasing hormone, testosterone, and 17 beta-estradiol in transgenic mice

Transient transfection studies have proven useful in unraveling the molecular mechanisms underlying gonadotrope-specific expression and hormonal regulation of the gene encoding the alpha-subunit of the glycoprotein hormones. In contrast, similar studies performed with the LH beta gene have been less informative. When assayed by transient transfection into alpha T3-1 cells, activity of a 776-basepair bovine LH beta promoter-chloramphenicol acetyltransferase fusion gene (bLH beta CAT) was no greater than that of a promoterless control. To determine whether limited activity in vitro reflected the absence of critical regulatory elements, we examined activity of bovine LH beta fusion genes after stable integration in transgenic mice. In contrast to transient transfection studies, the LH beta promoter targeted high levels of CAT expression specifically to the pituitary. In addition, a bLH beta TK fusion gene was active only in gonadotropes. The bLH beta CAT transgene was also evaluated for responsiveness to gonadal steroids and GnRH. Testosterone and 17 beta-estradiol were capable of suppressing activity 70-80% in castrated males, despite the absence of high affinity binding sites for androgen or estrogen receptors. This suggests that feedback inhibition of LH beta CAT transgene expression by gonadal steroids may occur through an indirect mechanism, possibly at the level of the hypothalamus. To address whether the bLH beta CAT transgene could be regulated by GnRH, we treated ovariectomized females with antide, a GnRH antagonist. Antide suppressed transgene activity by 60%. Thus, the proximal promoter of the bovine LH beta subunit gene directs appropriate patterns of cell-specific expression and retains responsiveness to gonadal steroids and GnRH. In light of the robust activity of the LH beta promoter in transgenic mice, we suggest that this animal model can be exploited further to dissect the complex mechanisms that underlie gonadotrope-specific expression and hormonal regulation of the LH beta gene.

The effect of recombinant human osteogenic protein-1 on healing of large segmental bone defects

A rabbit ulnar non-union model was used to evaluate the effect of recombinant human osteogenic protein-1 on the healing of a large segmental osteoperiosteal defect. A 1.5-centimeter segmental defect was created in the mid-part of the ulnar shaft of adult rabbits. The defect was filled with an implant containing either recombinant human osteogenic protein-1 or naturally occurring bovine osteogenic protein. The recombinant human osteogenic protein-1 implants consisted of a carrier of 125 milligrams of demineralized, guanidine-extracted, insoluble rabbit bone matrix (the collagen carrier), reconstituted with 3.13, 6.25, 12.5, twenty-five, fifty, 100, 200, 300, or 400 micrograms of recombinant human osteogenic protein-1. Animals that received recombinant human osteogenic protein-1 were compared with animals that received an implant of 250 micrograms of a preparation of naturally occurring bovine osteogenic protein mixed with the collagen carrier. Limbs that served as controls received either the collagen carrier alone or no implant at all. The treated and the untreated defects were examined radiographically and histologically at eight or twelve weeks after implantation. Mechanical testing was performed on six animals. All implants of recombinant human osteogenic protein-1, except for those containing 3.13 micrograms of the substance, induced complete radiographic osseous union within eight weeks. The defects that were treated with an implant of bovine osteogenic protein also healed within this time-period. The bone induced by both types of implants had new cortices with advanced remodeling and marrow elements. Histological evaluation of this new bone at eight weeks postoperatively revealed primarily lamellar bone, with the formation of new cortices and normal-appearing marrow elements. The average torsional strength and energy-absorption capacity of the union induced by recombinant human osteogenic protein-1 was comparable with that of intact bone. The control defects that had been implanted with collagen carrier alone and those with no implant showed no bridging of the defect.

Prognostic significance of right ventricular hypokinesis and perfusion lung scan defects in pulmonary embolism

We studied the relation between right ventricular (RV) hypokinesis on echocardiography and defects on the initial perfusion lung scan among 90 hemodynamically stable patients with pulmonary embolism (PE). Of the 90, 38 had qualitative evidence of RV hypokinesis, with a mean RV end-diastolic area significantly larger than those with normal RV wall motion (40.0 +/- 10.2 cm2 vs 20.1 +/- 6.4 cm2; p < 0.001). The degree of the perfusion defect was greater in those patients with baseline RV hypokinesis (54% +/- 16% of the lung nonperfused) than in those patients with normal RV wall motion at baseline (30% +/- 18% nonperfused lung; p < 0.001). Receiver operating characteristic curve analysis showed that a perfusion lung scan defect score of 0.3 (i.e., 30% of the lung nonperfused) had a 92% sensitivity for predicting RV hypokinesis and carried a relative risk for observing RV hypokinesis of 6.8 times greater than among those patients with a perfusion scan score of < 0.3. Considering that all patients with recurrent symptomatic PE were in the subgroup with RV hypokinesis (13% vs 0% for those with normal RV wall motion; p = 0.01), a strategy of performing echocardiography in those patients with a perfusion scan defect score of > or = 0.3 appears to identify patients at increased risk for recurrent PE.

Recombinant human bone morphogenetic protein-7 induces healing in a canine long-bone segmental defect model

An ulnar segmental defect model was used in adult male dogs to examine the effect of recombinant human bone morphogenetic protein-7 (recombinant human Osteogenic Protein-1 [rhOP-1]; Creative Biomolecules, Hopkinton, Massachusetts) on new bone induction and healing, and to test the mechanical strength of healed 2.5-cm segmental bone defects. The rhOP-1 composites consisted of a carrier of 500 mg of demineralized, guanidine-extracted, insoluble bovine bone matrix (collagen carrier), reconstituted with rhOP-1. Six animals received 1200 micrograms rhOP-1 unilaterally and were killed at 12 weeks for torsional load-to-failure testing using the contralateral side as a control. Two further animals received varying amounts of rhOP-1 bilaterally and were studied histologically. All defect sites receiving rhOP-1 were completely bridged radiographically by eight weeks. A control composite, containing no rhOP-1, failed to induce new bone formation at any time. Histologically, rhOP-1-treated sites examined at 16 weeks had formation of new cortical and cancellous bone, with normal appearing marrow elements in the reconstituted medullary canal. The torsional strength of the rhOP-1-implanted ulnae averaged 72% of control (range, 30-99%). The angular deformation to failure averaged 92% of control (range, 39-122%). The energy absorption to failure averaged 67% of control (range, 27-111%). This study demonstrates the efficacy of rhOP-1 in healing segmental osteoperiosteal defects in a canine model.

Season of the year influences concentration and pattern of gonadotropins and testosterone in circulation of the bovine male

Serum concentrations of LH vary with season of the year in ovariectomized beef and dairy cows. The objective of the present study was to determine whether concentrations and profile of the gonadotropins and testosterone (T) in circulation vary with season of year in bovine males of a composite breed type (beef). Five INTACT and five gonadectomized (GNX) males that were 22 mo of age at the initiation of the study were used. All of the males utilized were maintained on pasture throughout the year at the latitude of 41 degrees N. Blood samples were collected in a serial regimen (10-min intervals for 24 h) at the spring and fall equinox and the summer and winter solstice. Concentrations of LH were quantified in all samples, and concentrations of T were determined in all samples of the INTACT group. Concentrations of FSH and 17 beta-estradiol (E2) were quantified in pooled samples for all animals, while concentrations of T were determined in pooled samples for males from the GNX group. Pulse frequency of LH or T and mean concentration of FSH did not vary with season of the year. A seasonal effect on mean concentration of LH (p < 0.01) occurred in males of the GNX group, with mean concentrations of LH being greatest during the spring equinox and lowest during the winter solstice. Season had an effect on pulse amplitude of LH (p < 0.01), mean concentration of T (p < 0.01), and pulse amplitude of T (p < 0.05) in males from the INTACT group.(ABSTRACT TRUNCATED AT 250 WORDS)

Progesterone, 17 beta-estradiol, and opioid neuropeptides modulate pattern of luteinizing hormone in circulation of the cow

The working hypothesis for this study was that 17 beta-estradiol (E2), progesterone (P4), and opioid neuropeptides modulate frequency of pulsatile release of LH during the luteal phase of the bovine estrous cycle. On Day 8 of the estrous cycle (Day 0 = estrus), 20 cows were ovariectomized (OVX) and immediately received one of three steroid replacement treatments: P4 alone (n = 6), E2 alone (n = 7), or P4 and E2 (n = 7). To characterize the pattern of LH in peripheral circulation, serial blood samples were collected (12-min intervals for 22 h) on the fifth day following OVX. LHRH was administered after the 22-h sample was taken. Naloxone (opioid neuropeptide antagonist; 0.5 mg/kg) was administered on the sixth day after OVX, and change of concentration of LH in peripheral circulation was monitored. Pulse frequency of LH and mean concentration of LH were lower (p < 0.01) in cows treated with P4 and E2 compared to cows treated with P4 alone. Moreover, cows treated with E2 alone had a greater (p < 0.01) frequency of LH pulses and mean concentration of LH compared to cows treated with P4 alone. The greatest amplitude (p < 0.01) of LH release after LHRH was in cows treated with E2 alone. The greatest percentage increase (p < 0.01) in LH after administration of naloxone occurred in cows treated with P4 alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Increasing exogenous progesterone during synchronization of estrus decreases endogenous 17 beta-estradiol and increases conception in cows

The objectives of this study were to determine the effects of dose of exogenous progesterone (P4) prior to artificial insemination on concentrations of 17 beta-estradiol (E2) and on conception rates in bovine females. Heifers (n = 100) and cows (n = 100) received P4-releasing intravaginal devices (PRIDs) to produce two different circulating concentrations of P4. All animals received a single PRID 10 days before (Day-10) the start of the breeding season (Day 0). In animals that received the low dose of P4 (1 PRID, target concentration of 2-3 ng/ml of plasma), the original PRID remained in place for 10 days. In animals that received the larger dose of P4 (2 PRIDs, target concentration of 5-8 ng/ml of plasma), an additional PRID was inserted on Day -9. To maintain concentrations of P4 in the 2-PRID group, the PRIDs inserted on Days -10 and -9 were replaced with new PRIDs on Days -5 and -4, respectively. Prostaglandin F2 alpha (25 mg) was administered to all animals on Days -9 and -3 to remove the endogenous source of P4. Following PRID removal, animals were artificially inseminated 12 h after signs of behavioral estrus were observed. A treatment-by-day interaction (p < 0.0001) was observed for concentrations of P4 in circulation of both heifers and cows. Animals that received 2 PRIDs had greater (p < 0.001) concentrations of P4 by Day-8 of treatment than animals that received 1 PRID. In cows that received 1 PRID, concentrations of E2 increased 2.4-fold from Day-10 (6.8 +/- 1.0 pg/ml) to Day-2 (16.7 +/- 1.4 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Development of lower leg strength and flexibility with the strength shoe

The Strength Shoe is a modified athletic shoe with a 4-cm thick rubber platform attached to the front half of the sole. It is promoted as an effective method of increasing "speed, quickness, and explosive power," as well as ankle flexibility and calf circumference, when used in a plyometrics-based training regimen. This study evaluates, in a prospective, randomized trial, the efficacy and safety of the Strength Shoe training regimen for increasing lower leg flexibility and strength in intercollegiate track and field participants. No enhancement of flexibility, strength, or performance was observed for participants wearing the Strength Shoe at the end of an 8-week training program, following the suggested regimen of the manufacturer. The use of the Strength Shoe cannot be recommended as a safe, effective training method for development of lower leg strength and flexibility. However, the use of plyometrics in a properly supervised setting may improve athletic performance and merits further investigation.

Yearling bulls shorten the duration of postpartum anestrus in beef cows to the same extent as do mature bulls

The objective of this study was to determine whether yearling bulls, when pastured with cows, reduced the duration of postpartum anestrus to the same extent as did mature bulls. This experiment was conducted over a 3-yr period. Cows were stratified by parity group to achieve 37% 2-yr-old and 63% mature (> 2-yr-old) cows within each treatment group (approximately 50 cows per treatment per year). Cows were assigned in the order in which they calved to one of three treatment groups: 1) isolated from bulls (NBE; n = 158); 2) exposed to mature bulls that were > 3 yr of age (MBE; n = 154); or 3) exposed to bulls that were 1 yr of age (YBE; n = 152). Beginning the 2nd wk after calving, cows were pastured with either sterile bulls that were 1 yr (YBE) or > 3 yr of age (MBE) (three bulls per treatment group). Blood samples were collected twice weekly from late March until mid-July each year. Cows with serum concentrations of progesterone > 1 ng/mL for two consecutive sampling periods were assumed to have initiated estrous cycles after calving. Duration of postpartum anestrus in cows exposed to yearling bulls (YBE = 61.8 +/- 1.8 d) did not differ (P > .10) from duration of postpartum anestrus in cows exposed to mature bulls (MBE = 59.5 +/- 1.7 d). Duration of postpartum anestrus was shorter (P < .01) for cows exposed to bulls (MBE+YBE = 61.0 +/- 1.7 d) than for cows isolated from bulls (NBE = 72.3 +/- 1.8 d).(ABSTRACT TRUNCATED AT 250 WORDS)

Exogenous progesterone and progestins as used in estrous synchrony regimens do not mimic the corpus luteum in regulation of luteinizing hormone and 17 beta-estradiol in circulation of cows

Our working hypothesis was that the low concentrations of progesterone (P4) and synthetic progestins administered in hormonal regimens to control estrous cycles of cows would have similar effects on secretion of LH and 17 beta-estradiol (E2). In addition, we hypothesized that concentrations of exogenous P4 typical of the midluteal phase of the estrous cycle and the corpus luteum (CL) would have similar effects on LH and E2, and the effects would be different from those of synthetic progestins and low concentrations of P4. Cows (n = 29) were randomly assigned to one of five treatment groups: 1) one Progesterone Releasing Intravaginal Device (1PRID; n = 6); 2) two PRIDs (2PRID; n = 6); 3) norgestomet, as in Syncro-Mate-B regimen (SMB; n = 6); 4) melengestrol acetate (MGA; 0.5 mg/day; n = 5); and 5) control (CONT; n = 6). Treatments were administered for 9 days (Day 0 = initiation of treatment). All cows from 1PRID, 2PRID, SMB, and MGA groups were injected with prostaglandin F2 alpha (PGF2 alpha) on Days 2 and 5 of the treatment period to regress CL. Cows in the 1PRID and SMB groups were also administered exogenous estrogen according to the respective estrous synchronization protocol for these products. Daily blood samples were collected from Day 0 to 35 to determine concentrations of P4. On Day 8, blood samples were collected at 15-min intervals for 24 h to determine pattern of LH secretion. On Day 9, all treatments ceased and cows in the CONT group received injections of PGF2 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)