Predictors of firearm purchasing during the coronavirus pandemic in the United States: a cross-sectional study

OBJECTIVES

This study aimed to compare determinants of firearm purchasing related to the pandemic.

STUDY DESIGN

This was a cross-sectional survey.

METHODS

A total of 3853 online panel participants completed a survey between December 22, 2020, and January 2, 2021, to approximate a nationally representative sample of US adults (aged ≥18 years). Four firearm ownership groups were created: non-owners, a proxy for first-time COVID-19 owners, prepandemic owners with COVID-19 purchase, and prepandemic owners without COVID-19 purchase. Explanatory variables were in four domains: demographics, concern about the pandemic, actions taken in response to COVID-19, and emotional response to COVID-19. Multivariate analysis estimated the adjusted odds of the outcomes.

RESULTS

Respondents were categorized as non-owners (n = 2440), pandemic-related purchasers with no other firearms (n = 257), pandemic-related purchasers with other firearms (n = 350), and those who did not purchase in response to the pandemic but have other firearms (n = 806). Multivariable logistic regression found that compared with non-owners, those who had firearms at home with no pandemic-related purchases are more likely to be male, live in rural settings, have higher income, and be Republican.

CONCLUSIONS

The results highlight the changing profile of American firearm owners and identify that those who purchased firearms for the first time (in response to the pandemic) should be the focus of tailored public health interventions, including provision of education about recommended firearm storage to reduce firearm violence, particularly because they are more likely to have children at home, and belong to demographic groups that may have less experience with firearm safety.

Milk matrix effects on antibody binding analyzed by enzyme-linked immunosorbent assay and biolayer interferometry

Biolayer interferometry (BLI) was employed to study the impact of the milk matrix on the binding of ricin to asialofetuin (ASF) and to antibodies. This optical sensing platform used ligands immobilized covalently or via biotin-streptavidin linkage, and the results were compared to those obtained by enzyme-linked immunosorbent assay (ELISA). In sandwich ELISA, the binding of ricin to ASF was dramatically decreased when galactose was present during the analyte or detection antibody binding step. Low concentrations of milk (1%, v/v) produced a similar reduction in ricin binding to ASF but not to a high-affinity monoclonal antibody (mAb), increasing the dissociation rate of ASF-ricin complexes up to 100-fold. The effect of milk on the binding of ricin to ASF was ascribable to dialyzable factors, and milk sugar can account for these effects. The use of high-affinity mAbs in ELISA effectively limits the milk matrix effect on ricin analysis.

Production of specific mRNA transcripts, usage of an alternate promoter, and octamer-binding transcription factors influence the surface expression levels of the HIV coreceptor CCR5 on primary T cells

Surface levels of CCR5 on memory CD4(+) T cells influence HIV-1/AIDS susceptibility. Alternative promoter usage results in the generation of CCR5 mRNA isoforms that differ based on whether they contain or lack the untranslated exon 1. The impact of exon 1-containing transcripts on CCR5 surface expression is unknown. In this study, we show that the increased cell surface expression of CCR5 on primary T cells is associated with selective enrichment of exon 1-containing transcripts. The promoter that drives exon 1-containing transcripts is highly active in primary human T cells but not in transformed T cell lines. The transcription factors Oct-1 and -2 inhibit and enhance, respectively, the expression of exon 1-containing transcripts and CCR5 surface levels. However, polymorphisms at homologous octamer-binding sites in the CCR5 promoter of nonhuman primates abrogate the binding of these transcription factors. These results identify exon 1-containing transcripts, and the cis-trans factors that regulate the expression levels of these mRNA isoforms as key parameters that affect CCR5 surface expression levels, and by extension, susceptibility to HIV/AIDS among humans, and possibly, the observed interspecies differences in susceptibility to lentiviral infection.

Human breast cancer cell lines and tissues express tartrate-resistant acid phosphatase (TRAP)

Tartrate-resistant acid phosphatase (TRAP) is expressed by osteoclasts, macrophages and dendritic cells. TRAP has been identified in a wide variety of tissues, however, its biological function is not fully understood. Serum TRAP is a marker of diseases involving excessive bone resorption including metastatic bone disease in breast cancer patients and can be used to monitor responses to treatment. Our aim in this study was to determine whether TRAP is expressed by human breast tumours. Four breast cancer cell lines were assayed for TRAP activity. MDA-MB-435, the most tumourigenic line, had an activity twofold higher than the other cell lines. Immunohistochemistry using a TRAP specific antibody confirmed that both cell lines and human breast tumours express TRAP. Expression was absent in benign tissues and abundant in more aggressive tumours. This work suggests that tumour derived TRAP contributes to the raised enzyme activity found in the serum of breast cancer patients.

Acute scrotum in Nigeria: an 18-year review

One hundred and seventy-eight patients presenting with an acute scrotum during a period of 18 years (1978-1997) were reviewed retrospectively. Fifty per cent had testicular torsion, with a mean age of 23 years (range 3 weeks-55 years). Torsion was significantly more common in the cold harmattan season (October-early March). The salvage rate of torted testes was 52%. Inguinoscrotal hernia was the cause of testicular infarction in 10% and is an important contributor to male infertility. Twelve per cent of cases of suspected torsion were found to have epididymo-orchitis, at exploration. Twenty-three (13%) patients presented with scrotal gangrene (Fournier's gangrene) which did not result in testicular loss. There was significant morbidity following intervention by non-doctors, and misdiagnosis from unsuspecting physicians. The acute scrotum affecting young patients is a significant cause of male infertility and morbidity in Zaria. Early recognition, prompt treatment and re-education of those who may provide the first line care for such patients will reduce the morbidity and pathologic consequences following neglect.

Reference ranges for thyroid function tests in premature infants beyond the first week of life

OBJECTIVES

To establish reference ranges for the more sensitive assays of thyrotropin and the best available assays of free thyroxine in premature infants after the first week of life.

STUDY DESIGN

Free thyroxine measurements by direct equilibrium dialysis and thyrotropin measurements by third generation immunometric assay were measured in 120 healthy premature infants 25 to 36 weeks' gestation at birth and every 3 weeks until hospital discharge. Infants were stratified by postconceptional age. Differences in free thyroxine and thyrotropin levels among groups were determined by ANOVA. Correlations between hormone measurements and gestational and postnatal ages were sought by linear regression analysis. Reference ranges were determined as arithmetic (free thyroxine) and geometric (thyrotropin) mean+/-2 SD ranges.

RESULTS

From 120 infants, 164 samples were obtained and grouped by postconceptional age at sampling. Free thyroxine was not different among postconceptional age groups and did not correlate with gestational or postnatal age. The free thyroxine reference range based on these data was 10 to 33 pmol/l (0.8 to 2.6 ng/dl). Thyrotropin did not correlate with gestational age. There was a clinically trivial but statistically significant (r(2)=0.03, p<0.05) correlation of thyrotropin with postnatal age. The thyrotropin reference based on these data was 0.8 to 12 mU/l.

CONCLUSIONS

Free thyroxine was closely regulated in these premature infants and levels were similar to those in older children and adults, once the natal surge in thyrotropin has subsided. After the first week of life a single range for each hormone appeared appropriate for all premature infants until 40 weeks postconceptional age.

Differential effect of vinorelbine versus paclitaxel on ERK2 kinase activity during apoptosis in MCF-7 cells

The effects of vinorelbine and paclitaxel on the activity of extracellular signal-regulated protein kinase2 (ERK2), a member of MAP kinase, and its role in the induction of bcl-2 phosphorylation and apoptosis were evaluated in MCF-7 cells. We demonstrated that ERK2 was activated rapidly by vinorelbine, and was inhibited by either paclitaxel or estramustine. A 3-fold increase of ERK2 kinase activity was observed within 30 min when MCF-7 cells were treated with 0.1 microM vinorelbine. In contrast, the same treatment with paclitaxel resulted in a significant decrease of ERK2 kinase activity. We also demonstrated that elevated bcl-2 phosphorylation induced by vinorelbine is paralleled by decrease of a complex formation between bcl-2 and bax, cleavage of poly (ADP) ribose polymerase (PARP) protein, activation of caspase-7, and apoptosis. The levels of bcl-2 phosphorylation, bax, and PARP were not significantly affected by 2'-amino-3'-methoxyflavone (PD 98059), an ERK kinase specific inhibitor. Thus, our data suggest that the apoptosis induced by vinorelbine in MCF-7 cells is mediated through the bcl-2 phosphorylation/bax/caspases pathways, and that activation of ERK2 by vinorelbine does not directly lead to the drug-mediated apoptosis. Since decrease of PARP occurred quickly following the treatment of MCF-7 cells with either 0.1 microM of vinorelbine or paclitaxel, this protein may serve as an early indicator of apoptosis induced not only by DNA damaging agents, but also by antimicrotubule drugs.

SPC-100270, a protein kinase C inhibitor, reduced hypoxic injury due to reperfusion following orthotopic liver transplantation in the rat

Recently, we reported that SPC-100270, a sphingosine derivative and inhibitor of protein kinase C (50-90 microM) in mixed micelle assays, reduced reperfusion injury resulting from hypoxia in a low-flow, reflow model of liver perfusion. Here we report that SPC-100270 has similar beneficial effects following liver transplantation in vivo. Rat liver transplantation was performed using nonarterial and rearterial techniques. Livers from syngenic rats were harvested surgically, prepared with vascular cuffs and a splint, and stored for 24 or 48 h in University of Wisconsin (UW) cold storage solution. Just prior to completion of vascular reconstruction, the organ was rinsed with 3 or 10 ml of Ringer's solution, vehicle, or a solution containing SPC-100270 (up to 500 microM). Following implantation surgery, low doses of SPC-100270 were ineffective at reducing both parenchymal and nonparenchymal cell death, yet significant (P < 0.05) reductions were observed with 500 microM. Further, nonparechnymal cell viability was improved nearly four fold by the drug. SPC-100270 (500 microM) tended to increase survival following 48 h cold storage in UW solution, but the improvement was not statistically significant. SPC-100270 also did not diminish carbon-centered free radical formation in transplanted livers from alcohol-treated rats. Collectively, these data support the hypothesis that pretreatment of donor livers with an inhibitor of protein kinase C is effective in vivo at reducing reperfusion injury, particularly to nonparenchymal cells, following orthotopic liver transplantation in the rat.

Synergism of cytotoxic effects of vinorelbine and paclitaxel in vitro

Empiric combinations of vinca alkaloids with taxanes have been recently used in clinical oncology. To enhance the activity of these two classes of agents, we evaluated the sequence and duration of exposure, looking for synergistic effects. Cell lines DU 145, PC 3, LnCaP, LL 86, MCF7wt, and MCF7/ADR (NCI/ADR-RES) were incubated with varying concentrations of paclitaxel or vinorelbine. Cytotoxicity was evaluated by a semiautomated MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) method. Synergism or antagonism of these two agents either sequentially or in combination was determined by median effect analysis. Prolonged exposure of cells to either drug enhanced cytotoxic effect. Synergism or antagonism with vinorelbine and paclitaxel were both sequence dependent and cell line specific. In the case of MCF7wt, synergism was seen when a 48-hr exposure to vinorelbine preceded paclitaxel, whereas antagonism was noted when both agents were applied simultaneously or when the sequence was reversed. Concurrent vinorelbine and paclitaxel were synergistic in four of six cell lines when the exposure was extended to 96 hr but not for shorter durations of exposure. Sequential exposure of vinorelbine preceding paclitaxel or prolonged exposure to both agents concurrently needs to be tested clinically to determine whether the antitumor activity of this combination can be enhanced. In addition, these studies suggest concurrent administration of these two agents may lead to a less than optimal cytotoxic result.

Contribution of plasmid-encoded fimbriae and intimin to capacity of rabbit-specific enteropathogenic Escherichia coli to attach to and colonize rabbit intestine

Attachment to the intestinal mucosa is an essential step in the pathogenesis of diarrhea caused by enteropathogenic Escherichia coli (EPEC). Fimbriae and intimin, the outer membrane protein product of the chromosomal eae gene, contribute to this process, but their relative roles and the nature of their interaction are not known. The aim of this study was to determine the relative contribution of plasmid-encoded fimbriae, termed Ral, and intimin to the capacity of rabbit-specific EPEC (REPEC) to attach to the intestinal mucosa of rabbits. To achieve this, we constructed a series of mutants in REPEC strain 83/39 (O15:H-), in which the ralE and eae genes were insertionally inactivated. These strains were then inoculated into ligated loops of rabbit ileum, which were resected 18 h later and examined by light and electron microscopy. The results showed that intimin, but not Ral, is essential for the elicitation of attaching-effacing lesions by REPEC. Nevertheless, a delta eae Ral-bearing mutant adhered to the intestinal epithelium to the same extent as its eae-positive parent and far more extensively than an eae(+) delta ral strain. To examine the contribution of Ral and intimin to colonization of rabbit intestine, we fed these strains to weanling rabbits, which were killed 4 days later, so that the number of bacteria in various regions of the intestine could be determined. The results indicated that strain 83/39 requires both Ral and intimin to colonize the intestine successfully and that a delta eae delta ralE double mutant was incapable of colonizing the intestine. Taken together, these findings indicate that Ral and intimin act independently as adhesion factors of REPEC strain 83/39 and that this strain carries no other significant colonization factor. When both Ral and intimin are present, they appear to act cooperatively, with Ral-mediated adhesion preceding that mediated by intimin.

Infusional vinorelbine in relapsed or refractory lymphomas

Vinorelbine (Navelbine is a semisynthetic vinca alkaloid devoid of serious neurotoxicity. When given weekly vinorelbine has documented activity against many tumors, including lymphomas. Since weekly schedules cannot be easily incorporated in combination regimens, we tested an infusional schedule of vinorelbine given every 21 days in adults with relapsed or refractory lymphoma. Patients with inadequate organ or bone marrow reserve, HIV or other serious infection, central nervous system disease, or prior stem cell or bone marrow transplantation were ineligible. In the phase I part, patients received a constant intravenous bolus of 8 mg/m(2), followed by intravenous continuous infusion over 24 hours daily for four days increasing from 10, 12, to 14 mg/m(2) /d in successive three-patient cohorts. Cycles were repeated every 21 days, and the daily continuous infusion dose was adjusted for toxicity. Dose-limiting mucositis and neutropenia were reached at the continuous dose of 14 mg/m(2) /d. Consequently, for the Phase II trial the starting continuous infusion dose was 12 mg/m(2) /d. After the first 19 patients were entered in the phase II study, the starting infusion dose was reduced to 10 mg/m(2) /d because of frequent grade (3/4) myelosuppression and mucositis. Forty-four patients were entered in the phase II study, of whom 41 are evaluable. Median age was 61 years, 23 were males, with clinically aggressive non-Hodgkin's lymphoma (NHL) in 22, indolent NHL in 18, and Hodgkin's Disease in one patient. The median number of prior regimens was 3 (range 1-11). The lymphoma was refractory to the initial regimen in nine patients, and to the regimen immediately before vinorelbine in 20 patients. Serum LDH was high in 2(1/4)1, and serum beta(2) -microglobulin > 3.0 mg / L in 16/31 patients. Responses were observed in four of 22 patients with aggressive NHL (18%, 95% confidence interval 5%-40%), and in six of 18 with indolent NHL (33%, 95% confidence interval 13%-59%). Median progression-free survival was 6 months for responders. During the Phase II trial 114 vinorelbine courses were administered. Neutrophil nadir was < 1000/microl in 65% and < 100/microl in 35% of courses, respectively. Platelet nadir was < 100,000/microl in 30% and < 20,000/microl in 8% of courses, respectively. Grade (3/4) mucositis was seen in 18% of courses, and neutropenic fever in 13%, and was complicated by death in one patient. We conclude that this dosage and schedule of vinorelbine has modest activity in patients with relapsed or refractory NHL. Myelosuppression is frequent but reversible, but there is no significant neurotoxicity. The role of vinorelbine in combination regimens for patients with relapsed lymphomas, particularly those of indolent histology, should be further investigated.

Colonization of the respiratory tract by a virulent strain of avian Escherichia coli requires carriage of a conjugative plasmid

The E3 strain of E. coli was isolated in an outbreak of respiratory disease in broiler chickens, and experimental aerosol exposure of chickens to this strain induced disease similar to that seen in the field. In order to establish whether the virulent phenotype of this strain was associated with carriage of particular plasmids, four plasmid-cured derivatives, each lacking two or more of the plasmids carried by the wild-type strain, were assessed for virulence. Virulence was found to be associated with one large plasmid, pVM01. Plasmid pVM01 was marked by introduction of the transposon TnphoA, carrying kanamycin resistance, and was then cloned by transformation of E. coli strain DH5alpha. The cloned plasmid was then reintroduced by conjugation into an avirulent plasmid-cured derivative of strain E3 which lacked pVM01. The conjugant was shown to be as virulent as the wild-type strain E3, establishing that this plasmid is required for virulence following aerosol exposure. This virulence plasmid conferred expression of a hydroxamate siderophore, but not colicins, on both strain E3 and strain DH5alpha. Carriage of this plasmid was required for strain E3 to colonize the respiratory tracts of chickens but was not necessary for colonization of the gastrointestinal tract. However, the virulence plasmid did not confer virulence, or the capacity to colonize the respiratory tract, on strain DH5alpha. Thus, these studies have established that infection of chickens with E. coli strain E3 by the respiratory route is dependent on carriage of a conjugative virulence plasmid, which confers the capacity to colonize specifically the respiratory tract and which also carries genes for expression of a hydroxymate siderophore. These findings will facilitate identification of the specific genes required for virulence in these pathogens.

A phase I study of sequential vinorelbine followed by paclitaxel

BACKGROUND

In vitro experiments suggest that administration of vinorelbine preceding paclitaxel results in synergistic cytotoxic effects. A phase I dose escalation trial of vinorelbine daily x 3 with paclitaxel on day 3 repeated every 28 days in metastatic breast cancer patients was completed.

PATIENTS AND METHODS

Female patients, PS 0-2, without evidence of CNS disease or prior neuropathies were treated with vinorelbine at dose levels 7, 10, 13 mg/m2 per day and paclitaxel over three hours at dose levels of 135, 175, and 200 mg/m2.

RESULTS

Twenty-eight patients with six dose levels were studied. At dose level 1, patients developed intolerable but reversible neutropenia. Subsequent dose levels required filgrastim. Dose limiting toxicities were myalgia and fatigue at vinorelbine 13 mg/m2/day and paclitaxel 200 mg/m2. Neuropathy was minor. Twelve of twenty-five patients with measurable disease had a rapid response which did not correlate with dose level.

CONCLUSIONS

Sequential administration of these two agents demonstrates activity in breast cancer patients. Phase II dosing on this schedule should be vinorelbine 13 mg/m2/day x 3 and paclitaxel 175 mg/m2. With proper selection of patients, concern about neurologic toxicity should not impede future trials of vinorelbine with paclitaxel.

Selective early elimination of luteal support in assisted reproduction cycles using a gonadotropin-releasing hormone agonist during ovarian stimulation

OBJECTIVE

To determine if women undergoing GnRH agonist-hMG stimulated IVF cycles can undergo successful discontinuation of luteal phase support.

DESIGN

A protocol for selective discontinuation of luteal phase support was evaluated prospectively in women undergoing assisted reproduction cycles.

SETTING

A tertiary care institutional-based assisted reproduction program.

PATIENT(S)

One hundred eighty-eight women who conceived after an IVF or zygote intrafallopian transfer cycle including a GnRH agonist between January 1994 and June 1997.

INTERVENTION(S)

Women with serum progesterone levels of > or = 60 ng/mL at 4 weeks' gestation were selected for discontinuation of their luteal phase support.

MAIN OUTCOME MEASURE(S)

Delivery rate.

RESULT(S)

Sixty-three women (62.4%) met the criteria for discontinuation of luteal phase support. There were no differences in the mean age, peak E2 levels, number of follicles, number of embryos transferred, or delivery rates (85.7% versus 78.9%) between the women who did and those who did not have discontinuation of their progesterone supplementation.

CONCLUSION(S)

These data reveal that luteal phase support can be discontinued successfully for selective women undergoing IVF who are receiving a GnRH agonist.

Apoptosis in a neonatal rat model of cerebral hypoxia-ischemia

BACKGROUND AND PURPOSE

The mechanisms of excitotoxic cell death in cerebral ischemia are poorly understood. In addition to necrosis, apoptotic cell death may occur. The purpose of this study was to determine whether an established model of cerebral hypoxia-ischemia in the neonatal rat demonstrates any features of apoptosis.

METHODS

Seven-day-old neonatal rats underwent bilateral, permanent carotid ligation followed by 1 hour of hypoxia, and their brains were examined 1, 3, and 4 days after hypoxia-ischemia. The severity of ischemic damage was assessed in the dentate gyrus and frontotemporal cortex by light microscopy. Immunocytochemistry was performed to detect the cleavage of actin by caspases, a family of enzymes activated in apoptosis. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) reactivity was examined in the cortical infarction bed and dentate gyrus. Neonatal rat brain DNA was run on agarose gel electrophoresis to detect DNA fragmentation. Ethidium bromide-staining and electron microscopy were used to determine whether apoptotic bodies, 1 of the hallmarks of apoptosis, were present.

RESULTS

The frontotemporal cortex displayed evidence of infarction, and in most rats the dentate gyrus showed selective, delayed neuronal death. Immunocytochemistry demonstrated caspase-related cleavage of actin. TUNEL and DNA electrophoresis provided evidence of DNA fragmentation. Ethidium bromide-staining and electron microscopy confirmed the presence of chromatin condensation and apoptotic bodies.

CONCLUSIONS

Features of apoptosis are present in the described model of cerebral hypoxia-ischemia. Apoptosis may represent a mode of ischemic cell death that could be the target of novel treatments that could potentially expand the therapeutic window for stroke.

Refractive versus Corneal Changes After Photorefracive Keratectomy for Astigmatism

PURPOSE

To define measures of assessing success and subsequent ways to improve excimer laser treatment of astigmatism.

METHODS

We studied 97 eyes of 79 patients, followed for 12 months, that underwent photorefractive keratectomy (PRK) for myopia and astigmatism with a VISX 20/20 excimer laser. Preoperative spherical equivalent refraction at the corneal plane was between -1.00 and -15.00 D. Mean preoperative refractive astigmatism at the spectacle plan was -2.17 +/- 1.05 D (range, -1.25 to -6.00 D), which is -1.81 +/- 0.86 D (range -1.04 to -4.97 D) when calculated at the corneal plane. All patients were examined before and after surgery; examination included refraction, keratometry, and topography measurement.

RESULTS

The success in treatment of astigmatism appeared measurably less than the treatment of sphere when analogous indices were used for assessment. Success in astigmatism surgery improved, as measured by all parameters, after an additional 20% was applied to astigmatism treatment magnitude indicated by the VISX computer algorithm. The sequential modes of treatment undercorrected astigmatism magnitude to a greater extent than elliptical, but equivalent success rates were present in view of the greater astigmatic changes attempted using the sequential mode. The elliptical mode tended to produce a greater undercorrection of associated sphere (p = 0.313). Results measured by refraction showed a larger change than those measured by topography and keratometry.

CONCLUSION

During PRK with the VISX 20/20 laser, adjustment for undercorrection of astigmatism treatment achieves a fuller correction of astigmatism. When measuring astigmatic changes, results are different when comparing refractive astigmatism changes with corneal astigmatism changes measured by keratometry and topography.

Inhibition of leukotriene B4 (LTB4) in human neutrophils by L-threo-dihydrosphingosine

The sphingosine analog L-threo-dihydrosphingosine has been shown to inhibit protein kinase C (PKC) isoenzymes in mixed micelle and vesicle assays. This compound also inhibited the reactive oxygen intermediates (ROI) released from isolated neutrophils (IC50 approximately 2 microM) and phorbol ester-induced edema and neutrophil influx in the mouse ear model (ED50 approximately 11 mg/kg). Based on the anti-inflammatory activity of this compound, studies were done to determine its effect on arachidonate metabolism by the lipoxygenase pathway. Neutrophils were preincubated with test agents or vehicle for one minute and then incubated with 1 microM calcium ionophore A23187 for two minutes. Supernatants were assayed for LTB4 using a radioimmunoassay. The reference lipoxygenase inhibitor nordihydroguaiaretic acid exhibited 98.3% inhibition at 1 microM (n = 2) and prevented ROI production (IC50 approximately 6 microM). In contrast, the potent PKC inhibitor staurosporine was inactive against LTB4 in these studies (< 23% inhibition at 10 microM, n = 2), but inhibited ROI formation (IC50 approximately 3nM). L-threo-dihydrosphingosine inhibited LTB4 production 96.9 +/- 1.3%, at 10 microM (IC50 = 6 microM, n = 2). These data suggest that L-threo-dihydrosphingosine blocks the release of LTB4 from human neutrophils via a mechanism independent of PKC.

Role of a general surgeon in obstetrics and gynaecology in a rural setting

In a rural hospital in northern Nigeria, general surgeons performed 217 obstetric and gynaecologic operations over a five-year period. These operations were responsible for 23% of all operations at the hospital. Emergency operations were most frequent with caesarean section accounting for 90%. Eighty five per cent of the caesarean sections were performed for cephalopelvic dysproportion. The complications encountered were mostly septic complications, predominantly in patients who had caesarean section for obstructed labour. The overall mortality was 5.1% and neonatal mortality from caesarean section was 4.8%. It is concluded that in the abscence of an obstetrician and gynaecologist general surgery experience is required to manage obstetric and gynaecologic problems in rural areas. Such experience should be considered when recruiting doctors for rural hospitals in developing countries.

Identification and characterization of a K88- and CS31A-like operon of a rabbit enteropathogenic Escherichia coli strain which encodes fimbriae involved in the colonization of rabbit intestine

Initiation of attaching-effacing lesions, which characterize infections with rabbit enteropathogenic Escherichia coli (REPEC), requires bacteria to adhere to the intestinal epithelium. This adherence is reflected in vitro by the affinity of these E. coli strains for various types of eukaryotic cells. TnphoA mutants of REPEC 83/39 (O15:H-) which had lost the ability to adhere to HEp-2 epithelial cells, guinea pig ileal brush borders, and mouse erythrocytes were generated. DNA sequencing of the region surrounding the inactivating transposon insertions within a 95-kb plasmid, designated pRAP for REPEC adherence plasmid, revealed extensive homology between that region and the structural genes of enterotoxigenic E. coli operons encoding the K88 and CS31A fimbrial adhesins and the genes for the afr2 adhesin from REPEC B10 (O103:H2). Seven genes of the ral operon (for REPEC adherence locus), including three putative minor fimbrial subunit genes (ralC, ralF, and ralH), a major fimbrial subunit gene (ralG), a gene of unknown function (ralI), and genes for two fimbrial subunit chaperones (ralD and ralE), were sequenced. When inoculated perorally into weanling rabbits, a mutant with a TnphoA insertion in the ralE gene showed a 10-fold reduction in colonizing ability, with only 1 of 10 rabbits excreting bacteria compared to all 5 of those infected with the wild-type parent strain (P = 0.002). The severity of the diarrheal illness caused by the mutant strain was also reduced. Western blotting of surface protein extracts of strain 83/39 with hyperimmune anti-83/39 antiserum, adsorbed with the ralE mutant, revealed a 32-kDa protein which was absent from protein extracts of two nonadherent mutants. The adsorbed antiserum also bound to the surface of strain 83/39 but not to nonadherent mutants, as detected by immunogold labeling. These results indicate that the ral operon of REPEC 83/39 contains genes necessary for the biosynthesis of fine fimbriae which are responsible for in vitro adherence of the bacteria and play a role in their colonization of, and hence virulence for, rabbits. The putative major fimbrial subunit is a protein with an observed molecular size of approximately 32 kDa which, when assembled, appears to form a capsule of fimbriae surrounding the bacterium similar to that described for CS31A.

Morphometry of human lumbar apophyseal joints. A novel technique

STUDY DESIGN

The anatomy of cadaveric lumbar apophyseal joints was examined as part of a study of possible correlations between lumbar apophyseal morphology, arthrosis, and cartilage thickness and stiffness.

OBJECTIVES

To establish the morphometry of human upper lumbar apophyseal joints using an objective technique.

SUMMARY OF BACKGROUND DATA

The apophyseal joints of 30 unfixed lumbar motion segments, all from different cadavers (24 male, five female, and one unknown, mean age 35 years, range 16-78 years) were exposed by dissection and disarticulation. Twenty-five motion segments were L1-L2, three were L2-L3, and two were L3-L4. The extent of fibrillation and linear dimensions of 29 of these specimens were examined, whereas the vertebrae and joints of 22 of them (18 being L1-L2) were cast in araldite resin.

METHODS

The casts of the vertebrae were sectioned cephalocaudally at 1-mm intervals. Image processing of photographic slides of the sections established the orientations and dimensions of the lumbar apophyseal joints and their shapes using Fourier analysis.

RESULTS

Apophyseal joint surface area was 158 +/- 43 mm2, cephalocaudal length 15.2 +/- 2.7 mm, and straight line length between anterior and posterior borders was 13.2 +/- 1.9 mm. The joints were orientated at 62.5 +/- 11.8 degrees to the coronal plane. Average maximum depth of concavity was 1.8 +/- 0.7 mm. The posterior edges of two joint pairs twisted inward toward the midsagittal plane in a cephalocaudal direction; thus, some apophyseal joints bear part of the axial spinal load. The right inferior surfaces were more elongated cephalocaudally (but not longer) than their contralateral partners. Inferior apophyses were significantly more elongated cephalocaudally (but not longer) than their ipsilateral articulating superior surfaces.

CONCLUSIONS

In theory, Fourier analysis of joint surfaces was objective, but it dictated the criterion by which joints were grouped; care must be exercised so that measurement methods do not categorize joints artificially. "Symmetry" is too subjective to be applied to contralateral apophyseal joints; correlation coefficients should be quoted for areas and orientations. The morphology of contralateral lumbar apophyseal joint pairs was significantly correlated in all respects, as was the morphology of articulating lumbar apophyseal surfaces.

Blunt traumatic injury of the gallbladder in childhood

OBJECTIVE

To illustrate blunt traumatic injury of the gallbladder in childhood.

DESIGN

A case report.

SETTING

Hospital.

SUBJECT

An eight year old boy.

MAIN OUTCOME MEASURE

Incidence, history, treatment.

RESULT

The gallbladder was ruptured at the neck necessitating a cholecystectomy. The child has remained well at three months follow up.

CONCLUSIONS

Blunt traumatic injury of the gallbladder, though rare, does occur usually as a consequence of direct abdominal injury especially in children during sporting activities and fights. Minor injuries can be repaired but cholecystectomy is necessary in more extensive injuries or injury to the cystic duct and neck. A comprehensive history taking including direct questioning regarding trauma and a high index of suspicion are important for early diagnosis and prompt treatment.

Felbamate protects CA1 neurons from apoptosis in a gerbil model of global ischemia

BACKGROUND AND PURPOSE

Felbamate, a novel anticonvulsant that binds to the glycine site of the N-methyl-D-aspartate receptor, has been shown to have neuroprotective properties in vitro and in vivo. In a rat pup model of hypoxia-ischemia, felbamate selectively reduced delayed death in hippocampal granule cells. The present study explores its neuroprotective potential in a gerbil model of global ischemia, in which good evidence exists that ischemia triggers apoptosis of CA1.

METHODS

Gerbils were subjected to bilateral carotid occlusion for 5 minutes and then treated with felbamate (100 or 200 mg/kg IV) or vehicle. They were killed 3 days later, and the numbers of live and dead neurons in the CA1 sector of the hippocampus were counted at sterotaxically defined levels.

RESULTS

Felbamate (200 mg/kg IV) administered after the release of carotid clamping did not change brain temperature but reduced neuronal death in CA1 from 332 +/- 60 cells per section of dorsal hippocampus in unmedicated gerbils to 62 +/- 12 cells in felbamate-treated animals (P<.001). A lower dose of felbamate (100 mg/kg post hoc) showed only a nonsignificant reduction of neuronal death. In the 200-mg/kg group, felbamate serum concentrations peaked at 162 microg/mL and were above 100 microg/mL for at least 3 hours, and brain levels reached 150 microg/mL at 1 hour. In the 100-mg/kg group, blood serum levels were well below 100 microg/mL.

CONCLUSIONS

These results suggest that felbamate given post hoc is remarkably effective in preventing delayed apoptosis secondary to global ischemia but that effective neuroprotection requires doses higher than those used for anticonvulsant treatment.

Human lumbar apophyseal joint damage and intervertebral disc degeneration

OBJECTIVES

To record the extent and location of lumbar apophyseal cartilage damage, and to ascertain if the extent of damage is correlated with the grade of disc degeneration, age, or both.

METHODS

The extent and location of fibrillated areas of the apophyseal cartilage of the joint surfaces of 29 lumbar motion segments were examined using computer aided image processing of Indian ink stained areas, and degeneration of the associated intervertebral discs graded using the method of Nachemson.

RESULTS

It was found that these joints showed a greater extent and prevalence of cartilage fibrillation than the knee, hip or ankle, with significant damage in specimens younger than 30 years. Damage was predominantly located peripherally, superiorly, and posteriorly in the concave superior apophyseal surfaces, and was predominantly peripheral and posterior in the inferior surfaces, with a tendency to be located inferiorly. There was a weak correlation between apophyseal joint damage and the intervertebral disc degenerative grade, but this was inconclusive, as both increased with age.

CONCLUSIONS

The pattern of damage exhibited by superior joint surfaces is most probably caused by tension on collagenous joint capsule fibres which insert into the surfaces posteriorly, so producing an area of fibrocartilage unsuited to loadbearing. Tension on such fibres would be greatest during spinal flexion. The pattern of damage of the inferior surfaces lends some support to the hypothesis that their apices impact the laminae of the lumbar vertebra inferior to them, consequent upon the degeneration and narrowing of the associated intervertebral disc. The predominantly peripheral location of fibrillation of both superior and inferior surfaces may be associated with inadequate mechanical conditioning of marginal joint areas. Disc degeneration cannot be the initial cause of apophyseal fibrillation in most specimens. The study indicates a need for regular spinal exercise, starting at a young age.

Naturally occurring protein kinase C inhibitors; II. Isolation of oligomeric stilbenes from Caragana sinica

The oligomeric stilbenes (+)-alpha-viniferin (1), miyabenol C (2), and kobophenol A (3) have been isolated from Caragana sinica (Buchoz) Rehd (Leguminosae). (+)-alpha-Viniferin (1) and miyabenol C (2) exhibited protein kinase C inhibitory activity at low micromolar concentrations. (+)-alpha-Viniferin inhibited keratinocyte proliferation (0.4 microM) and free radical release in whole blood (47 microM), in vitro, and may be useful in treating hyperproliferative or inflammatory skin diseases.

Reference ranges for newer thyroid function tests in premature infants

OBJECTIVE

To establish reference ranges for recently developed assays of thyroid function in premature infants.

METHODS

We measured serum free thyroxine (T4) by direct equilibrium dialysis and serum thyrotropin by a sensitive immunometric method in 104 preterm infants (25 to 36 weeks of gestational age) during the first week of life.

RESULTS

The free T4 level correlated positively with gestational age (p < 0.0001; r2 = 0.09) and differed significantly between adjacent gestational age groups (p < 0.05). Free T4 concentrations (mean +/- SD) for the 25- to 27-, 28-to 30-, 31- to 33-, and 34- to 36-week groups were 18.0 +/- 5.2, 25.7 +/- 9.0, 30.9 +/- 9.0, 36.0 +/- 10.3 pmol/L (1.4 +/- 0.4, 2.0 +/- 0.7, 2.8 +/- 0.8 ng/dl), respectively. Two reference ranges for free T4 were determined, one for 25 to 30 weeks (6.4 to 42.5 pmol/L (0.5 to 3.3 ng/dl) and one for 31 to 36 weeks (16.7 to 60.5 pmol/L (1.3 to 4.7 ng/dl)). The logarithm of the value for thyrotropin correlated positively with gestational age (p < 0.001; r2 = 0.08); one reference range of 0.5 to 29 mU/L was determined for thyrotropin.

CONCLUSION

This study extends information on thyroid function of preterm infants and establishes reference ranges for this population.

Host specificity of enteropathogenic Escherichia coli from rabbits: lack of correlation between adherence in vitro and pathogenicity for laboratory animals

The pathogenicity of four attaching and effacing strains of enteropathogenic Escherichia coli originally isolated from diarrheic rabbits was investigated by inoculating them perorally into rabbits, guinea pigs, and mice. The ability of the four strains to adhere to cultured epithelial cells, erythrocytes, and intestinal brush borders from various animal species, including rabbits, guinea pigs, and mice, varied considerably. Only one strain carried AF/R1 fimbriae, which are believed to determine the host specificity of these bacteria. Despite these differences, the pattern of behavior of the four strains in experimentally infected animals was similar. Each strain caused fatal diarrhea in rabbits (although the virulence of individual strains for rabbits differed significantly), and none was virulent for guinea pigs or mice. None of the strains colonized the intestinal tract of guinea pigs, but all were able to cause attaching-effacing lesions in ligated loops of guinea pig small intestine. By contrast, all four strains colonized mice, in particular the distal intestine, but none induced attaching-effacing lesions in mouse intestinal loops. These findings suggest that there may be previously unrecognized host-restricted adhesins in enteropathogenic E. coli and indicate that adherence to erythrocytes or intestinal brush borders in vitro does not necessarily reflect colonizing ability or pathogenicity in vivo.

Adherence characteristics of attaching and effacing strains of Escherichia coli from rabbits

Twelve strains of Escherichia coli previously reported to cause diarrhea in rabbits were examined for properties associated with virulence. Ten strains met the criteria for classification as enteropathogenic E. coli in that they were diarrheagenic strains that evoked attaching-effacing lesions in the small intestine and did not produce detectable enterotoxins or cytotoxins. These bacteria exhibited a variety of patterns when investigated for adherence to HEp-2 epithelial cells. Although several strains displayed localized and/or diffuse adherence to epithelial cells, they did not hybridize with DNA probes that recognize the genes responsible for these phenotypes in diarrheagenic E. coli from humans. The bacteria also varied in their ability to bind to erythrocytes and intestinal brush borders from various animal species. Six strains adhered to rabbit brush borders; two of these also adhered to brush borders from other animals. Two strains that did not adhere to rabbit brush borders adhered to those from guinea pigs or sheep. Only one of the strains investigated carried AF/R1 fimbriae, which are believed to govern the host specificity of this category of diarrheagenic E. coli. This strain was E. coli RDEC-1, which remains the only E. coli strain to date that is known to carry fimbriae of this type. The results indicate that although diarrheagenic E. coli strains from rabbits may have common properties associated with the ability to produce attaching-effacing lesions, they differ from each other and from enteropathogenic E. coli of humans in terms of some of the adhesins that mediate binding to eukaryotic cells.

The Stiffness of Human Apophyseal Articular Cartilage as an Indicator of Joint Loading

The stiffness and thickness distribution of healthy lumbar apophyseal cartilage was measured in 25 lumbar motion segments (L1–4). The cartilage indentation and needling techniques of Swann and Seedhom (37) were suitably altered to cope with the low modulus and small size of the joint surfaces. A load of 3.12 ± 0.19 N (mean ± s.d.) was applied to the cartilage through a hemispherical indenter of 4.756 mm diameter. The stiffness was calculated using the displacement and instantaneous load 150 ms and 2 s after the indenter first contacted the surface, and using the equations of both Waters (46) and Hayes et al. (47). The mean stiffness of apophyseal joint cartilage was 2.8 M Pa ± 4 per cent (mean ± 95 per cent confidence limit), and thickness 1.02 mm ± 3 per cent. Peripheral apophyseal joint cartilage was softer than central cartilage. The stiffnesses of the centres of the superior and inferior joint surfaces were 3.01 MPa ± 12 per cent and 3.55 MPa ± 11 per cent. Inferior surfaces had a mean thickness of 0.93 mm ± 5 per cent and stiffness of 2.88 MPa ± 7 per cent. Superior surfaces had a mean thickness of 1.10 mm ± 4 per cent and stiffness of 2.74 MPa ± 5 per cent. It was found that the stiffness of cartilage calculated according to the formula of Hayes et al. (47), based on a constitutive analysis of a thin isotropic elastic layer, was directly proportional to both the stiffness calculated using the semi-empirical formula of Waters (46), derived to describe indentation of thin rubber sheets, and the nominal compressive creep modulus calculated by dividing the mean contact stress by the strain at the deepest point of indentation. The creep modulus calculated 2 s after contact was directly proportional to the creep modulus calculated 150 ms after indenter contact, implying that deformation behaviour was uniform between these points despite variation of cartilage stiffness.

Rapamycin prolongs survival and arrests pathophysiologic changes in murine systemic lupus erythematosus

OBJECTIVE

To evaluate the effects of oral rapamycin (RAPA), a macrolide immunosuppressant that has been shown to interfere with T cell activation events, on the course of spontaneous disease progression in the MRL/MpJ/lpr/lpr (MRL/l) mouse model of lupus.

METHODS

RAPA treatment (6, 12, or 25 mg/kg 3 times per week) was evaluated by monitoring survival rates, autoantibody levels, and urinary albumin levels. Additionally, concanavalin A responsiveness, interleukin-2 (IL-2) production, lymphoid organ size, and histopathology were evaluated ex vivo.

RESULTS

RAPA prevented the typical rise in anti-double-stranded DNA antibody and urinary albumin levels and prolonged survival. Spleen and lymph node sizes were significantly decreased, inflammatory changes in the lung, liver, kidney, spleen, lymph node, and thymus were significantly reduced, and T cell mitogen-stimulated splenocyte proliferation and IL-2 production were restored.

CONCLUSION

Data from 3 independent experiments demonstrated that RAPA significantly reduced or prevented many pathologic features of lupus normally seen in the MRL/l mouse, and suggest that RAPA may be useful as a therapeutic agent in SLE in humans.

Posthypoxic treatment with felbamate is neuroprotective in a rat model of hypoxia-ischemia

Felbamate, a novel dicarbamate anticonvulsant that blocks the glycine site of the N-methyl-D-aspartate receptor and protects the hippocampal slice from hypoxic damage, shows remarkably low toxicity in animals and in humans. Since most treatment of human cerebral ischemia will have to be delivered after the insult, we investigated the neuroprotective potency of post hoc felbamate in rat pups with bilateral carotid ligations exposed to an atmosphere of 6.5% O2 for 1 hour. Brain temperature was unaffected by surgery, hypoxia, or felbamate. Neuroprotection was greatest at 300 mg/kg, less effective at 200 and 400 mg/kg, and ineffective at 100 mg/kg. Post hoc felbamate (300 mg/kg) reduced the volume of infarction from 67% +/- 7% of neocortex in unmedicated rats to 32% +/- 8%, 51% +/- 12%, 38% +/- 19%, and 53% +/- 10% when given 0, 1, 2, and 4 hours after hypoxic exposure, respectively. By 6 hours, post hoc protection was no longer significant. Delayed neuronal necrosis in hippocampal granule cells was reduced from 156 +/- 33 neurons to 12 +/- 7 (0 hours, p < 0.01) and 37 +/- 17 (1 hour, p < 0.05). These effects were obtained at plasma concentrations (60 to 120 mg/ml) that have occasionally been reached without serious toxicity in human anticonvulsant trials. These data suggest that, in this animal model, felbamate given after a hypoxic-ischemic insult is effective in reducing cerebral infarction and extremely effective in preventing delayed neuronal necrosis, but that the window of opportunity for post hoc treatment is only 1 to 4 hours.

A prospective controlled investigation of the cognitive effects of amateur boxing

Eighty six amateur boxers underwent a series of neuropsychological assessments on three occasions--pre bout, immediate post bout and follow up within two years; 31 water polo players and 47 rugby union players acted as controls. The neuropsychological tests were selected as being sensitive to subtle cognitive dysfunction and formed part of a battery of other neurological and ophthalmic assessments. No evidence of neuropsychological dysfunction due to boxing was found, either following a bout or a series of bouts at follow up. None of a range of parameters including number of previous contests, recovery from an earlier bout, number of head blows received during a bout and number of bouts between initial assessment and follow up, were found to be related to changes in cognitive functioning.

A modification of the in vivo mixed lymphocyte reaction and rapamycin's effect in this model

Rapamycin, a novel macrocyclic immunosuppressive agent, suppresses murine T cell activation in vitro by mechanisms distinct from cyclosporin A (CsA). This study was designed to examine rapamycin and CsA in the host vs graft popliteal lymph node (PLN) model, an in vivo system of T cell-dependent lymphocyte activation. The PLN procedure was modified by using irradiated CTLL-2 cells of C57BL/6 origin, instead of primary mouse splenocytes, as the allogeneic stimulus in C3H/HeN recipient mice. PLN cell proliferation was determined by [3H]-thymidine uptake. We found that the host lymphocyte proliferative response to CTLL-2 cells (H-2b) is greater than the response to mouse Balb/c splenocytes (H-2d). Rapamycin (ip or po) produced a dose-related inhibition of the in vivo mixed lymphocyte reaction. By contrast, the effects of CsA and FK-506 were not dose related within the same dose range (0.006-12 mg/kg). These data indicate that rapamycin is an effective immunosuppressive agent and confirm its ability to affect the allogeneic T cell response in vivo. Furthermore, the pharmacological data suggest that this PLN model utilizing irradiated CTLL-2 cells as an allogeneic stimulus provides a reproducible system to examine mixed lymphocyte reactions in vivo.

Rapamycin prevents the onset of insulin-dependent diabetes mellitus (IDDM) in NOD mice

The effect of the immunosuppressive agent rapamycin (RAPA) was assessed in the non-obese diabetic (NOD) mouse which is an autoimmune model of IDDM. RAPA was prepared in a vehicle of 8% cremophor EL/2% ethanol and investigated in two studies. NOD/MrK female mice (six per group, study no. 1; 10 per group, study no. 2) were dosed three times per week p.o. by gavage from 56 to 170 days of age (study no. 1) or from 64 to 176 days of age (study no. 2). Mice treated with RAPA at 0.6 mg/kg, 6 mg/kg, or 12 mg/kg maintained normal plasma glucose through 170 or 176 days of age with 10%, 0%, and 0% incidence of diabetes respectively. In contrast, naive, vehicle-treated, or RAPA 0.06 mg/kg-treated mice exhibited elevated plasma glucose and disease incidence typical for female NOD mice. Mice which became diabetic had elevated levels of beta-hydroxybutyrate, triglycerides and cholesterol. These plasma lipid concentrations were positively correlated with the duration of hyperglycaemia (r = 0.85, 0.87 and 0.84 respectively). Outside of its ability to prevent diabetes, RAPA itself did not affect the lipid profile of the mice. Intervention therapy with RAPA was ineffective at reversing the course of disease after IDDM onset under these experimental conditions. Finally, we report here that prophylactic treatment with RAPA was able to protect against IDDM development in some RAPA-treated mice 41 weeks after cessation of treatment. These data show that orally administered RAPA is effective in preventing onset of disease in the NOD mouse, a relevant model of autoimmune type I diabetes in man.

Felbamate reduces hypoxic-ischemic brain damage in vivo

The neuroprotective effects of felbamate were tested in a model of incomplete cerebral ischemia and hypoxia in 7-day-old rat pups. Felbamate pretreatment (300 mg/kg) reduced the surface of infarcted cortex following bilateral carotid ligation, by 42-49% compared to saline and dimethylsulfoxide (DMSO) controls, respectively. The number of necrotic neurons in the dentate gyrus was reduced by 77% over both DMSO controls and saline controls. These results suggest that felbamate deserves further evaluation for its therapeutic potential in hypoxia-ischemia.

Inhibition of interleukin-1 (IL-1) induced neutral proteases from rabbit articular chondrocytes by WY-46,135 and WY-48,989

The effects of potential anti-osteoarthritic compounds both on the direct inhibition of collagenase and neutral protease activities and on IL-1 induced release of neutral proteases from rabbit articular chondrocytes were investigated. WY-46,135 ((+)-N-[[[(5-chloro-2-benzothiazolyl)thio]phenyl]acetyl]-L- cysteine) directly inhibited collagenase activity (IC50 = 15.4 microM). This inhibition was reversible upon dialysis. WY-46,135 also directly inhibited neutral protease activity (IC50 = 16.8 microM) but did not significantly block bacterial collagenase activity at a concentration of 80 microM. In contrast, WY-48,989 (4-[[2-(7-chloro-2-phenyl-2H-pyrazolo[4,3-c]quinolin-4- yl)ethyl]amino]benzonitrile) did not directly inhibit either collagenase (10 microM) or neutral protease (100 microM) activity. Both WY-48,989 and WY-46,135 inhibited IL-1 stimulated release of neutral proteases (IC50 = 3 microM). The activities of these compounds represents two potential approaches for the treatment of osteoarthritis. WY-46,135 combines direct metalloprotease inhibitory activity with the inhibition of IL-1 stimulated neutral protease release from articular chondrocytes while WY-48,989 selectively inhibits the IL-1 induced release of metalloproteases.

Electrophysiological evidence for the involvement of the locus coeruleus in alerting, orienting, and attending

In this chapter, we describe recent observations from our laboratory which support the thesis that the locus coeruleus (LC), via its massively divergent efferent projections, participates in generating a generalized brain state that can be characterized as "alertness." The first of these observations suggests that LC activation can convert the electroencephalographic (EEG) activity of the forebrain from patterns characteristic of a non-alert state to those characteristic of an alert state. The second observation indicates that LC activation alters sensory responses of individual neocortical neurons in a way that is compatible with the general thesis presented here, suggesting that LC-induced alterations in cortical neuronal activity may be an integral component of a hypothesized participation of the LC in cortically mediated attentional processes. The third observation indicates that LC may modulate forebrain components of orienting responses that are indexed by event-related potentials (ERPs). Thus, the experiments described below involve electrophysiological assessment of forebrain information processing at three different levels of organization: activity of individual neurons in the millisecond range, neuronal ensemble activity persisting for 10-200 msec as indexed by ERPs, and ensemble/regional activity sustained for seconds to minutes as indicated by EEG measures. These observations suggest that alterations induced in forebrain function by manipulations of LC activity are evident at all three of these levels.

Effects of locally infused pharmacological agents on spontaneous and sensory-evoked activity of locus coeruleus neurons

Electrophysiological activity of individual locus coeruleus (LC) neurons was recorded in halothane-anesthetized rats before, during, and after the infusion of adrenergic, cholinergic, or peptidergic compounds about 400 micron lateral to LC. The alpha-adrenergic agonist clonidine (CLON), in concentrations ranging from 5-20 microM (67-270 pg/50 nl injection), reversibly suppressed activity with latencies to onset of 5-15 min and durations of 20-120 min. During the onset of suppressed firing, responses to sensory stimuli (footshock) were relatively preserved, but at later times the reliability of footshock responses was greatly reduced. The alpha-adrenergic antagonist piperoxane (PIP) rapidly reversed the inhibitory effects of CLON. Infusion of 0.1 microliter of 0.02 M acetylcholine (ACh) produced a 3-4 min period of increased LC firing, with a 1 min latency to onset. Larger volumes (0.15 microliter) produced greater increases in firing rate lasting 10-12 min. ACh effects were readily reversed with equimolar doses of scopolamine (SCOP). The effects of 0.02 M ACh were also rapidly reversed by equal volumes of 0.001 M CLON, SCOP and CLON reduced basal firing rates without blocking responses to sensory stimuli. Infusion of the cholinergic agonist carbamyl-beta-choline (carbachol) produced robust, reliable activation of LC neurons at doses of 25-1,000 ng per 100 nl injection. The electrophysiological effects of 3 adrenocorticotropin hormone (ACTH) fragments [1-24], [4-10], and [1-10] were also evaluated. ACTH[1-10] and ACTH[4-10] decreased LC activity for up to 2 hr. ACTH[1-24] exhibited more complex effects, with an increase in discharge rate being accompanied by a decrease in action potential amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of neutrophils with vascular smooth muscle: identification of a neutrophil-derived relaxing factor

Experiments were designed to study the interaction of rat peritoneal neutrophils with the vascular smooth muscle of the rat aorta. Rings of aorta, suspended in 10-ml organ chambers containing a physiologic salt solution, were precontracted with phenylephrine. Neutrophils (1 X 10(5) -4 X 10(7) cells/organ chamber) caused a cell number-dependent relaxation of the rat aorta that was augmented by superoxide dismutase (100 U/ml) or changing the oxygen content from 95 to 21%. The neutrophil-induced smooth muscle relaxation occurred in rings with and without endothelium and in rings precontracted with increasing concentrations of phenylephrine, prostaglandin F2 alpha or KCI. Catalase (1000 U/ml) and mannitol (1 X 10(-3) M) did not block the neutrophil-induced relaxation, whereas phenazine methosulfate (1 X 10(-5) M), hydroquinone (3 X 10(-5) M) and methylene blue (1 X 10(-5) M) reversed the neutrophil-induced relaxation. Pre-exposure of endothelium-rubbed rings to neutrophils (2 X 10(7) cells/organ chamber; 15 min) depressed the subsequent concentration-response curve to phenylephrine but augmented the relaxation induced by the phosphodiesterase inhibitor zaprinast (1 X 10(-5) M). The effluent from a column restraining the neutrophils induced a relaxation of endothelium-rubbed aortic rings that was prevented by methylene blue (1 X 10(-5) M). These results demonstrate that rat neutrophils release a factor that has a pharmacologic profile similar to that previously reported for the relaxing factor released from the vascular endothelium.

Enhanced in vitro proliferation and in vivo tumorigenic potential of mammary epithelium from BALB/c mice exposed in vivo to gamma-radiation and/or 7,12-dimethylbenz[a]anthracene

Virgin female BALB/c mice were exposed in vivo to whole body gamma-radiation and/or to 7,12-dimethylbenz[a]anthracene (DMBA) p.o. Mammary epithelial cells were isolated and assayed for carcinogen altered cell populations both in vitro by an epithelial focus assay and in vivo by injection into cleared fat pads of syngeneic host mice. Five groups of mice were exposed as follows: (a) sham controls; (b) 50-rad gamma-radiation; (c) 100-rad gamma-radiation; (d) 75 micrograms DMBA; or (e) 50-rad gamma-radiation followed in 1 week by 75 micrograms DMBA. Mammary epithelial cells were isolated and assayed at 24 h and at 1, 4, 16, and 52 weeks after in vivo exposure. Four to 12 mice per treatment per time point were individually assayed. Altered in vitro growth potential was characterized by the proliferation of carcinogen exposed (but not control) cells as epithelial foci which persisted at least 12 weeks in primary culture. Epithelial foci which could then be subcultured at least four times were termed subculturable epithelial foci. Altered in vivo morphogenic potential was characterized by dysplastic or neoplastic growth in host fat pads. With increased time in situ between exposure and assay, cell populations emerged which exhibited both increased in vitro subculturability and enhanced tumorigenic potential including a host response upon injection in vivo. Further, combined radiation and DMBA resulted in higher frequencies of subculturable epithelial foci than either treatment alone. The relevance of these progressive cellular changes to the process of mammary tumor development is discussed.

Characterization of an inbred strain of the SENCAR mouse that is highly sensitive to phorbol esters

An inbred strain of SENCAR mice was developed that is more sensitive to two-stage skin carcinogenesis protocols than the outbred parental stock. These mice, registered as SSIN/UTSP, were compared to the SENCAR in initiation-promotion protocols using the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) twice weekly for 22 weeks at dose levels of 0.5, 1.0 and 2.0 micrograms. With 0.5 microgram of TPA, the number of papillomas in the SSIN was 3-fold higher than in the SEN-CAR; the tumor incidence was 100 versus 60%, respectively. Similar, although less dramatic, results were found with 1.0 and 2.0 micrograms of TPA. In two-step promotion protocols using TPA twice weekly for 2 weeks and 2 micrograms mezerein twice weekly for 15 weeks the SSIN produced approximately 50% more tumors than the SENCAR at 0.5 microgram of TPA. At 2 micrograms of TPA the tumor response between the two mice was not significantly different. Epidermal hyperplasia was considerably greater in the SSIN at 0.5 microgram of TPA as was ornithine decarboxylase activity. These TPA-sensitive inbred mice should be useful in investigations on the biochemical and genetic factors involved in skin tumor promotion.

Effects of anti-promoters and strain of mouse on tumor promoter-induced oxidants in murine epidermal cells

The induction of oxidant production in mouse epidermal cells by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) can be suppressed by many, but not all, known inhibitors of mouse skin tumor promotion. Members of the anti-oxidant category that were tested were ranked in the following order, 7,8-benzoflavone greater than butylated hydroxyanisole greater than ascorbic acid. In the retinoid category, retinoic acid was only moderately effective, while the trimethoxymethylphenyl analog had at least twice the inhibitory activity. Among the six protease inhibitors examined, tosylphenylalanine chloromethylketone and tosyllysine chloromethylketone were effective in diminishing the response while tosylarginine methylester, antipain, leupeptin and soybean trypsin inhibitor were ineffective, suggesting that proteases are probably not involved in the oxidant response. Several agents, trifluoperazine, trisialoganglioside and diolein, that have been shown to suppress TPA activity in other cell systems were also found to suppress the oxidant response. Finally, the extent of the oxidant response was found to correlate with sensitivity to TPA tumor promotion among the three strains of mice tested: SSIn greater than SENCAR greater than C57BL/6J.

Measurement of biological shape: a general method applied to mouse vertebrae

A method is described for recording and analysing the projected shape of mouse vertebrae. The image of the shape is captured by a television camera, cleaned, digitized and subjected to mathematical analysis. A visual representation is obtained by reconstructing the shape in polar coordinates about its centre of area. Further statistical analysis of the whole shape is performed after a Fourier transform. This allows the shape to be represented by and reconstructed from 15 numbers. The method does not rely on homologous points or expert opinion and allows mean shapes to be constructed. It successfully distinguished between 92% of the test data, T1 and T2 vertebrae from two strains of mice.