Thrombspondin acts via integrin-associated protein to activate the platelet integrin alphaIIbbeta3

Integrin-associated protein (IAP or CD47) is a receptor for the cell/platelet-binding domain (CBD) of thrombospondin-1 (TS1), the most abundant protein of platelet alpha granules. Although it associates with alphaIIbbeta3, IAP has no known function in platelets. TS1, the CBD, and an IAP agonist peptide (4N1K) from the CBD of TS1 activate the platelet integrin alphaIIbbeta3, resulting in platelet spreading on immobilized fibrinogen, stimulation of platelet aggregation, and enhanced tyrosine phosphorylation of focal adhesion kinase. Furthermore, 4N1K peptide selectively stimulates the phosphorylation of LYN and SYK and their association with FAK. The phosphorylation of SYK is blocked by pertussis toxin, implicating a Gi-like heterotrimeric G protein. IAP solublized from membranes of unstimulated platelets binds specifically to an affinity column of 4N1K peptide. Both alphaIIb and beta3 integrin subunits and c-Src bind along with IAP. This complex of proteins is also detected with immunoprecipitation. Activation of platelets with the agonist peptide 4N1K results in the association of FAK with the IAP-alphaIIbbeta3 complex. Thus an important function of TS1 in platelets is that of a secreted costimulator of alphaIIbbeta3 whose unique properties result in its localization to the platelet surface and the fibrin clot.

An unusual presentation of vulvar carcinoma: a traumatic aetiology?

Images

Hepatitis C virus core and E2 protein expression in transgenic mice

Transgenic mice have been produced that express the hepatitis C virus (HCV) core protein in the liver under the transcriptional control of the mouse major urinary protein promoter. These animals express the full length core protein in cytoplasm of their hepatocytes at levels comparable to those detected in naturally infected patients, without histological or biochemical evidence of liver disease or hepatocellular carcinoma. This contrasts with recent reports that HCV core protein can transform NIH 3T3 cells and cooperates with H-ras to transform primary rat fibroblasts in vitro. Coexpression of HCV core protein in double transgenic mice that replicate the hepatitis B virus (HBV) does not inhibit hepatocellular HBV gene expression or replication, contrary to reports that it inhibits HBV replication in HuH-7 cells after transient transfection in vitro. We have also produced transgenic mice in which a C-terminally truncated (aa384-715) glycosylated HCV E2 protein is expressed in the liver under the transcriptional control of the mouse albumin promoter. Despite the high level expression of HCV E2 protein, no evidence of liver disease was detected in these animals. These results suggest that the HCV core and E2 proteins are not cytopathic for the hepatocyte in vivo, and they represent an initial step in the development of a small animal model of HCV immunopathology.

A comparison of surgeons' posture during laparoscopic and open surgical procedures

BACKGROUND

There is increasing recognition of surgeons' physical fatigue in the new ergonomic environment of laparoscopic surgery. The purpose of this study was to determine what the differences are in the movement of the surgeon's axial skeleton between laparoscopic and open operations.

METHODS

Surgeons' body positions were recorded on videotape during four laparoscopic (LAP) and six open (OP) operations. The percent of time the head and back were in a normal, bent, or twisted position as well as the number of changes in head and back position were tabulated using a computer program. A separate laboratory study was performed on four surgeons "walking" a 0.5-inch polyethylene tubing forward and backward using laparoscopic and open techniques. The movements of the surgeons' head, trunk, and pelvis were measured using a three-camera kinematic system (Kin). The center of pressure was recorded using a floor-mounted forceplate (Fp).

RESULTS

In the operating room surgeons' head and back positions were more often straight in laparoscopic procedures and more often bent in open operations. The number of changes in back position per minute were significantly decreased when the laparoscopic-only part of surgery was analyzed. In the laboratory the subjects' head position was significantly (p = 0.02) more upright and the anteroposterior (AP) and rotational range of motion of the head was significantly reduced during laparoscopy. Subjects' CP was more anterior and there was a significant reduction in the AP range of motion of the CP during laparoscopy.

CONCLUSIONS

Our study suggests that surgeons exhibit decreased mobility of the head and back and less anteroposterior weight shifting during laparoscopic manipulations despite a more upright posture. This more restricted posture during laparoscopic surgery may induce fatigue by limiting the natural changes in body posture that occur during open surgery.

Prominent pigmented fungiform papillae of the tongue

Prominent pigmented fungiform paillae of the tongue are characterized clinically by prominence and pigmentation confined to these papillae and histopathologically by melanophages in the lamina opriae. A 45-year-old Asian woman had dark erythematous papules exclusively involved with fungiform papillae on the anterior lateral dorsal aspect of the tongue and hyperpigmentation on the lip. Histologic examination revealed many melanophages in the subepidermal area within the fungiform papillae. Her skin lesions improved moderately following two months of treatment for anemia.

Hybrid cysts showing alternate combination of eruptive vellus hair cyst, steatocystoma multiplex, and epidermoid cyst, and an association among the three conditions

Eruptive vellus hair cyst (EVHC), steatocystoma multiplex (SM), and epidermoid cyst are characterized by formation of multiple cutaneous cysts and have a resemblance in clinical features but have distinctive histologic features. We present herein two patients, who had EVHC, SM, and EVHC with sebaceous gland, and who also had EVHC, SM, and epidermoid cyst with sebaceous gland and vellus hairs. In addition, the interrelation among the three diseases is discussed. We think that EVHC, SM and epidermoid cyst are within the same spectrum of the disease process.

NMR solution structure of Cu(I) rusticyanin from Thiobacillus ferrooxidans: structural basis for the extreme acid stability and redox potential

The solution structure of the Cu(I) form of the rusticyanin from Thiobacillus ferrooxidans has been calculated from a total of 1979 distance and dihedral angle constraints derived from 1H, 13C and 15N NMR spectra. The structures reveal two beta-sheets, one of six strands and one of seven strands that are tightly packed in a beta-barrel or beta-sandwich arrangement, and a short helix that extends on the outside of one of the sheets to form a second hydrophobic core. The copper coordination sphere is composed of the standard type I ligands (His2CysMet) in a distorted tetrahedral arrangement. The copper-binding site is located within a hydrophobic region at one end of the molecule, surrounded by a number of aromatic rings and hydrophobic residues. This configuration probably contributes to the acid stability of the copper site, since close association of the aromatic rings with the histidine ligands would sterically hinder their dissociation from the copper. An electrostatic analysis based on a comparison of the structures of rusticyanin and French bean plastocyanin shows that factors determining the high redox potential of rusticyanin include contributions from charged side-chains and from the disposition of backbone peptide dipoles, particularly in the 81 to 86 region of the sequence and the ligand cysteine residue. These interactions should also contribute to the acid stability by inhibiting protonation of His143.

Interleukin-13 is a potent activator of JAK3 and STAT6 in cells expressing interleukin-2 receptor-gamma and interleukin-4 receptor-alpha

The lymphocyte growth factors interleukin-2 (IL2), IL4, IL7, IL9 and IL15 use the common IL2 receptor-gamma (IL2R gamma) and activate the IL2R gamma-associated tyrosine kinase JAK3 (Janus kinase 3). IL13 is structurally related to IL4, competes with IL4 for binding to cell surface receptors and exhibits many similar biological effects. The molecular basis for this functional overlap between IL4 and IL13 has been attributed mainly to a shared use of the 140 kDa IL4R alpha, since these cytokines appear to be uniquely different in that, according to several recent reports, IL13 does not recruit the IL2R gamma or JAK3. This notion has been supported by the identification of a novel 70 kDa IL13 receptor in certain IL13-responsive cell lines that lack IL2R gamma. The present study sheds new light on the issue of functional overlap between IL13 and IL4, by demonstrating for the first time that, in cells that express both IL2R gamma and IL4R alpha, IL13 can mimic IL4-induced heterodimerization of IL2R gamma and IL4R alpha, with consequent marked activation of JAK3 and the transcription factor STAT6 (IL4-STAT). Reconstitution experiments in BA/F3 cells showed that both cytokines require the simultaneous presence of IL4R alpha and IL2R gamma to mediate JAK3 and proliferative responses, and analysis of 12 IL4R alpha variants showed that IL4 and IL13 signals were equally affected by mutations of the cytoplasmic domain. We conclude that IL13 activates the IL2R gamma-associated JAK3 tyrosine kinase in appropriate cell types, and propose that IL13 is capable of interacting with multiple receptor subunits in a cell-dependent and combinatorial manner. Consequently, we predict that partial disruption of IL13 signal transduction also contributes to the severe combined immuno-deficiency syndromes associated with inactivation of the IL2R gamma or JAK3 genes.

Congenital cartilaginous rests of the neck

We describe a case of congenital cartilaginous rests of the neck arising on the suprasternal midline area of the neck in a Korean infant. The lesion was characterized by discrete nodules of mature elastic cartilage in the lower dermis or superficial subcutaneous soft tissue and multiple vellus hair follicles in the overlying skin.

Chromatin structure and gene expression

It is now well understood that chromatin structure is perturbed in the neighborhood of expressed genes. This is most obvious in the neighborhood of promoters and enhancers, where hypersensitivity to nucleases marks sites that no longer carry canonical nucleosomes, and to which transcription factors bind. To study the relationship between transcription factor binding and the generation of these hypersensitive regions, we mutated individual cis-acting regulatory elements within the enhancer that lies between the chicken beta- and epsilon-globin genes. Constructions carrying the mutant enhancer were introduced by stable transformation into an avian erythroid cell line. We observed that weakening the enhancer resulted in creation of two classes of site: those still completely accessible to nuclease attack and those that were completely blocked. This all-or-none behavior suggests a mechanism by which chromatin structure can act to sharpen the response of developmental systems to changing concentrations of regulatory factors. Another problem raised by chromatin structure concerns the establishment of boundaries between active and inactive chromatin domains. We have identified a DNA element at the 5' end of the chicken beta-globin locus, near such a boundary, that has the properties of an insulator; in test constructions, it blocks the action of an enhancer on a promoter when it is placed between them. We describe the properties and partial dissection of this sequence. A third problem is posed by the continued presence of nucleosomes on transcribed genes, which might prevent the passage of RNA polymerase. We show, however, that a prokaryotic polymerase can transcribe through a histone octamer on a simple chromatin template. The analysis of this process reveals that an octamer is capable of transferring from a position in front of the polymerase to one behind, without ever losing its attachment to the DNA.

Transforming growth factor beta 1 supports autonomous growth of human papillomavirus-immortalized cervical keratinocytes under conditions promoting squamous differentiation

Transforming growth factor beta (TGF-beta) inhibits proliferation of keratinocytes cultured from normal anogenital epithelia; however, human papillomavirus (HPV)-immortalized cell lines often exhibit increased resistance. Present results demonstrate that TGF-beta 1 (1-10 pM) stimulates growth of multiple HPV-immortalized cell lines when cultures are maintained under conditions promoting squamous differentiation (MCDB153-LB medium with 1.0 mM calcium and without epidermal growth factor and bovine pituitary extract). Growth stimulation by TGF-beta 1 was not due to altered expression of type I or II receptors, but was increased after extended passage of cells in culture. Differentiation of immortal keratinocytes resulted in induction of RNAs encoding two markers of squamous differentiation, involucrin and keratin 1, and decreased expression of RNAs for the epidermal growth factor (EGF) receptor and two ligands, amphiregulin and TGF-alpha. Growth stimulation by TGF-beta 1 occurred indirectly via establishment of an autocrine loop. TGF-beta 1 increased expression of RNAs encoding the EGF-R and amphiregulin, and also increased numbers of cell-surface EGF-Rs without altering their affinity. In contrast, TGF-beta 1 inhibited autonomous growth and transcription of amphiregulin RNA in normal keratinocytes. Growth stimulation by TGF-beta 1 could be blocked by a monoclonal antibody that competes for binding to the EGF-R or by a mixture of monoclonal antibodies that neutralize amphiregulin activity, confirming the importance of this autocrine pathway. Thus, partial abrogation of the growth inhibitory response to TGF-beta 1 sensitizes HPV-immortalized keratinocytes to a growth stimulatory signal mediated by an EGF-R-dependent pathway involving autocrine stimulation by amphiregulin.

IL-4-dependent proliferation of BA/F3 cells expressing a growth-negative mutant of the human IL-4 receptor is restored by enforced expression of Bcl-2

We have studied the regulation of growth and apoptosis in murine BA/F3 cells stably expressing cytoplasmic deletion mutants of the human interleukin-4 receptor (hIL-4R). Previously, we showed that BA/F3 cell transfectants expressing a cytoplasmic deletion mutant of the hIL-4R that lacks the region between Thr(462) and Ala(580), referred to as delta R3, fails to proliferate in the presence of hIL-4. Here we report that supertransfection of delta R3-expressing cells with a constitutively active murine bcl-2 gene results in prolonged survival of the delta R3/bel-2 double transfectants in the absence of cytokines. More importantly, however, the constitutive expression of Bcl-2 restored their capacity to grow permanently with hIL-4. This may provide an explanation for the discrepancy with previous reports showing growth mediation by hIL-4R truncated at position 367.

Mechanisms of tumor-induced hypoglycemia with intraabdominal hemangiopericytoma

The association of hypoglycemia with nonislet cell tumors is well recognized and in nearly all instances has been related to the production of hormones with insulin-like activity. To determine the mechanism of such tumor-induced hypoglycemia and the response to pharmacological intervention, we studied a 54-yr-old man with refractory hypoglycemia and a large intraabdominal hemangiopericytoma. During a supervised fast, plasma glucose decreased to 2.2 mmol/L. Circulating insulin (< 7 pmol/L), C peptide (< 0.04 nmol/L), and GH levels (< 0.6 microgram/L) were all undetectable, insulin-like growth factor I (IGF-I; 5 nmol/L) was low, IGF-II was in the normal range (87 nmol/L), and free IGF-II and big IGF-II (E1-21 fragment) were elevated at 18 and 142 nmol/L, respectively. On another day, after maintaining euglycemia overnight with a 20% dextrose infusion, a euglycemic (5.0-5.5 mmol/L) glucose clamp study using [3-3H]glucose tracer infusion combined with arteriovenous leg catheterization was performed in the postabsorptive basal state and during 3 h of crystalline somatostatin infusion (0.08-0.24 pmol/kg min). In the postabsorptive state at euglycemia, free IGF-II and big IGF-II remained elevated at 16 and 162 nmol/L, respectively. Whole body glucose disposal was elevated at 21.1 mumol/kg.min, whereas the rate of glucose infusion was 12.1 mumol/kg.min, and depatic glucose output was 7.8 mumol/kg.min. The leg arterio-venous plasma glucose difference was increased at 0.6 mmol/L, as was leg glucose uptake at 203.9 mumol/min. After 3 h of somatostatin infusion, both free and big IGF-II decreased by 35-40% to 10 and 102 nmol/L, respectively. Whole body glucose disposal also decreased to near normal (12.8 mumol/kg.min), whereas leg arterio-venous plasma glucose difference and leg glucose uptake became negligible. The plasma glucose level remained at 5.0-5.5 mmol/L despite a marked fall in hepatic glucose output to 2.9 mumol/kg.min and a decrease in glucose infusion rate to 8.7 mumol/kg.min. During somatostatin treatment, GH remained suppressed at less than 0.6 microgram/L, and glucagon decreased from 99 to 78 ng/L. In this patient with a hemangiopericytoma, hypoglycemia was associated with increased circulating insulin-like activity from elevated free and big IGF-II, which stimulated glucose uptake primarily into muscle tissue. A continuous infusion of crystalline somatostatin effectively reduced the elevated levels of IGF-II and glucose uptake, but was unable to adequately control hypoglycemia without the simultaneous infusion of exogenous glucose or glucagon.

Expression of enhanced spontaneous and gamma-ray-induced apoptosis by lymphocytes of the wasted mouse

Mice bearing the autosomal recessive mutation wasted (wst/wst) display a disease pattern including increased sensitivity of lymphocytes to ionizing radiation, neurologic dysfunction, and immunodeficiency. Many of the features of this mouse model have suggested a premature or increased spontaneous frequency of apoptosis in thymocytes. Past work has documented an inability to establish cultured T cell lines, and abnormally high death rate of stimulated T cells in culture, and an increased sensitivity of T cells to the killing effects of ionizing radiations in the wst/wst mouse relative to controls. The experiments reported here were designed to examine splenic and thymic lymphocytes from the wasted and control mouse for signs of early apoptosis. Our results revealed enhanced expression of Rp-8 mRNA (which has been associated with apoptosis) in thymic lymphocytes and to a lesser extent in spinal cord in the wst/wst mouse relative to controls; expression of Rp-2 and Tcl-30 mRNA (also reported to be induced during apoptosis) were not detectable in spleen or thymus. Expression of Rp-2, Rp-8, and Tcl-30 mRNA in other affected tissues of the wasted mouse (brain and liver) were similar in the wasted mouse and controls. Thymus and spleen from the wasted mouse have reduced numbers of viable cells relative to controls. Higher spontaneous DNA fragmentation was observed in lymphocytes from the wasted mouse than in controls; however, gamma-ray-induced DNA fragmentation peaked at a lower dose and occurred to a greater extent in lymphocytes derived from the wasted mouse relative to controls. These results suggest that high spontaneous and gamma-ray-induced apoptosis in T cells of the wasted mouse may contribute to the mechanism underlying the observed lymphocyte and DNA repair abnormalities.

Duplex sonography of the carotid arteries in patients with isolated aortic stenosis: imaging findings and relation to severity of stenosis

OBJECTIVE

The purposes of this study were to identify carotid artery duplex waveform abnormalities in patients with isolated aortic stenosis and to determine whether waveform abnormalities correlate with the severity of valvular disease.

MATERIALS AND METHODS

Twenty-four patients with various degrees of aortic stenosis diagnosed by echocardiography and/or cardiac catheterization had preoperative carotid artery duplex sonograms that were retrospectively reviewed for acceleration time, peak velocity, waveform contour, upstroke delay, and presence of a dicrotic notch and a second systolic peak. Data were collected for the right and left internal, external, and common carotid arteries separately. These findings were correlated with aortic valve area and compared with data for a control group of 11 age-matched patients with normal echocardiographic findings. Two additional patients with isolated aortic stenosis diagnosed by echocardiography and/or cardiac catheterization were prospectively evaluated in a similar fashion, with acceleration time being calculated directly from the sonography unit.

RESULTS

Unlike the patients with mild or moderate stenosis, the patients with critical or severe stenosis had a mean acceleration time that was significantly longer than that in the control subjects (p = .008-.0001). Peak velocities were decreased in all cases of aortic stenosis regardless of severity only in the common carotid arteries. All 13 patients with critical aortic stenosis had delayed upstrokes and rounded waveforms in the common, internal, and external carotid arteries. Twenty percent (one of five) of the patients with severe stenosis and 17% (one of six) of the patients with moderate or mild stenosis also had these characteristics. The two prospectively evaluated patients, who had critical and severe aortic stenoses, had similar findings. None of the control subjects showed these abnormalities. The presence or absence of a second systolic peak or a dicrotic notch was not different between patients with aortic stenosis and control subjects.

CONCLUSION

Increased acceleration time, decreased peak velocity, delayed upstroke, and rounded waveform are characteristic abnormalities found in duplex sonographic studies of the carotid arteries in patients with aortic stenosis. The degree of each of these abnormalities correlates with the valve area. Patients with critical or severe aortic stenosis had findings significantly different from those in the control group. Patients with mild or moderate disease showed few or no sonographic abnormalities.

Phosphotyrosine-independent binding of a 62-kDa protein to the src homology 2 (SH2) domain of p56lck and its regulation by phosphorylation of Ser-59 in the lck unique N-terminal region

A previously undescribed 62-kDa protein (p62) that does not contain phosphotyrosine but, nevertheless, binds specifically to the isolated src homology 2 (SH2) domain of p56lck has been identified. The additional presence of the unique N-terminal region of p56lck prevents p62 binding to the SH2 domain. However, phosphorylation at Ser-59 (or alternatively, its mutation to Glu) reverses the inhibition and allows interaction of the p56lck SH2 domain with p62. Moreover, p62 is associated with a serine/threonine kinase activity and also binds to ras GTPase-activating protein, a negative regulator of the ras signaling pathway. Thus, phosphotyrosine-independent binding of p62 to the p56lck SH2 domain appears to provide an alternative pathway for p56lck signaling that is regulated by Ser-59 phosphorylation.

Long-term outcomes and modes of death of patients treated with nonthoracotomy implantable defibrillators

Long-term outcomes of all patients who underwent nonthoracotomy implantable cardioverter-defibrillator (ICD) implantation at our institution from April 1991 to October 1994 were studied using the intention-to-treat analysis. Of 94 consecutive patients, 81 underwent nonthoracotomy ICD implantation and 13 underwent thoracotomy (for concomitant surgery in 11 and unavailability of nonthoracotomy leads in 2). Six of 81 patients had a high defibrillation threshold, 4 subsequently underwent thoracotomy, and 2 were treated with amiodarone. Surgical mortality was 0%. The duration of follow-up was 20 +/- 13 months, and was > 12 months in 74% of 67 living patients. Actuarial survival rates at 1 and 2 years were, respectively, 98% and 94% for sudden death and 91% and 83% for total mortality. Deaths during long-term follow-up were mostly due to nonsudden cardiac or noncardiac deaths. Two-year mortality rates were 12% and 25% in patients with ejection fraction > or = 30% and < 30%, respectively. Thus, instances of sudden death and surgical mortality are very few in patients with nonthoracotomy ICDs. Deaths during long-term follow-up are mostly due to nonsudden cardiac and noncardiac deaths. Therefore, ICD therapy may have greater impact on survival in patients with lower risks of nonsudden cardiac and cardiac death (e.g., younger patients with minimal heart disease) than in patients with severe cardiac or noncardiac disease. Prospective studies are needed to address this question.

Differential expression of HLA-DQB1 alleles in a heterozygous cell line

Regulation of HLA class II transcription is complex, with both locus-specific and allele-specific polymorphisms associated with consensus regulatory region promoter elements. In order to evaluate the potential function of allele-specific elements, HLA-DQB1 transcripts and in vivo footprinting of the DQB1 promoter were studied in human cell lines inducible for HLA class II expression. In the heterozygous melanoma cell line Me9229/18, differential expression was observed for two DQB1 alleles. This variation was reflected in both steady-state and inducible transcripts, although methylation patterns of the promoter elements were similar for both alleles. This in vivo allelic difference expression, which correlates with previous studies of in vitro reporter gene transcription, indicates the potential for functionally important differences in tissue-specific and inducible expression attributable to promoter region polymorphism in HLA genes.

Distinct sequence motifs within the cytoplasmic domain of the human IL-4 receptor differentially regulate apoptosis inhibition and cell growth

Hematopoietin receptors generally function as multimeric complexes composed of a unique ligand-binding chain and a second component often shared between several members of this receptor family. To better understand the signal transduction of the human IL-4 receptor (hIL4R), we analyzed the functionality of targeted mutations in two cytoplasmic regions of the ligand-binding hIL4R chain that we previously identified to be necessary for growth mediation in factor-dependent murine Ba/F3 cells. Here, we provide evidence that transient inhibition of apoptotic death of Ba/F3 cells and the competence to proliferate indefinitely depend on separated and distinct sequence motifs of the hIL4R. In particular, hIL4R constructs with a truncation of the recently described gp130 box1 from P242 to K264, or a deletion of the acidic region between S330 and S365, fail to stimulate growth or to mediate the inhibition of apoptosis. hIL4R bearing a point mutation within the gp130 box1 (P242S) is defective for growth stimulation but still signals the transient inhibition of apoptotic cell death and the induction of c-myc RNA. A third region required for IL4-mediated cell growth is localized between T462 and S476 and includes the sequence NPAY previously described to serve as interaction motif in signaling of epidermal growth factor and insulin receptors. Conversion of Y472 into F472 within the latter hIL4R motif affects the competence of stably transfected BA/F3 cells to proliferate indefinitely in the presence of hIL4. Sequences C-terminal of S476 are not essential for growth stimulation of BA/F3 transfectants.

Distinct sequence motifs within the cytoplasmic domain of the human IL-4 receptor differentially regulate apoptosis inhibition and cell growth

Hematopoietin receptors generally function as multimeric complexes composed of a unique ligand-binding chain and a second component often shared between several members of this receptor family. To better understand the signal transduction of the human IL-4 receptor (hIL4R), we analyzed the functionality of targeted mutations in two cytoplasmic regions of the ligand-binding hIL4R chain that we previously identified to be necessary for growth mediation in factor-dependent murine Ba/F3 cells. Here, we provide evidence that transient inhibition of apoptotic death of Ba/F3 cells and the competence to proliferate indefinitely depend on separated and distinct sequence motifs of the hIL4R. In particular, hIL4R constructs with a truncation of the recently described gp130 box1 from P242 to K264, or a deletion of the acidic region between S330 and S365, fail to stimulate growth or to mediate the inhibition of apoptosis. hIL4R bearing a point mutation within the gp130 box1 (P242S) is defective for growth stimulation but still signals the transient inhibition of apoptotic cell death and the induction of c-myc RNA. A third region required for IL4-mediated cell growth is localized between T462 and S476 and includes the sequence NPAY previously described to serve as interaction motif in signaling of epidermal growth factor and insulin receptors. Conversion of Y472 into F472 within the latter hIL4R motif affects the competence of stably transfected BA/F3 cells to proliferate indefinitely in the presence of hIL4. Sequences C-terminal of S476 are not essential for growth stimulation of BA/F3 transfectants.

Determination of sulfadimethoxine withdrawal time from milk. Part II: Statistical assessment

A statistical method is proposed to establish milk discard time for the data set described in Part I (preceding paper). Results are compared with those from the Food and Drug Administration (FDA)-recommended method. The milk discard time is established on the basis of a calculated tolerance limit. This limit provides 95% confidence that 99% of the population residue would assay below the permitted concentration (10 ppb for SDM). Unlike the FDA method, the proposed method allows easy calculation and requires no assumptions in drug depletion rate over time. For a permitted concentration of 10 ppb, both methods confirm the present 60-h discard time for SDM when it is assumed that no more than 1/3 of the milk came from treated cows.

Antidiuretic hormone levels and polyuria in spinal cord injury. A preliminary report

Chronic cervical spinal cord injury is characterized by defects in sodium and water homeostasis and defects of adaptive hormonal responses. The plasma osmolality is maintained in a relatively narrow range, the lower limit of which is determined by osmotic threshold for vasopressin release and the upper limit by the third threshold. Antidiuretic hormone as an important mediator of fluid and electrolyte balance was well investigated in able bodied children comparing children with normal voiding pattern and children with enuresis. The normal subjects were found to have higher plasma ADH at night, not detected in the group with enuresis. The findings were similar in elderly patients with increased diuresis at night, suggesting an important role of ADH in nocturnal decrease of urine output. Investigators studied the effect of rapid tilt on plasma ADH in tetraplegic compared with normal subjects, but there are no data available in the literature regarding ADH and its effects on water and electrolyte balance in healthy tetraplegic subjects with a normal lifestyle. We decided to undertake a pilot study to attempt to establish baseline ADH levels in this subject group, to better understand and manage tetraplegic patients with water and electrolyte dysregulation. Our preliminary data suggest that these individuals lack the normal diurnal variation of ADH, a phenomenon similar to that demonstrated in enuretic children and elderly, and furthermore appear to have generally depressed ADH levels.

Activation of pp70/85 S6 kinases in interleukin-2-responsive lymphoid cells is mediated by phosphatidylinositol 3-kinase and inhibited by cyclic AMP

Activation of phosphatidylinositol 3-kinase (PI3K) and activation of the 70/85-kDa S6 protein kinases (alpha II and alpha I isoforms, referred to collectively as pp70S6k) have been independently linked to the regulation of cell proliferation. We demonstrate that these kinases lie on the same signalling pathway and that PI3K mediates the activation of pp70 by the cytokine interleukin-2 (IL-2). We also show that the activation of pp70S6k can be blocked at different points along the signalling pathway by using specific inhibitors of T-cell proliferation. Inhibition of PI3K activity with structurally unrelated but highly specific PI3K inhibitors (wortmannin or LY294002) results in inhibition of IL-2-dependent but not phorbol ester (conventional protein kinase C [cPKC])-dependent pp70S6k activation. The T-cell immunosuppressant rapamycin potently antagonizes IL-2-(PI3K)- and phorbol ester (cPKC)-mediated activation of pp70S6k. Thus, wortmannin and rapamycin antagonize IL-2-mediated activation of pp70S6k at distinct points along the PI3K-regulated signalling pathway, or rapamycin antagonizes another pathway required for pp70S6k activity. Agents that raise the concentration of intracellular cyclic AMP (cAMP) and activate cAMP-dependent protein kinase (PKA) also inhibit IL-2-dependent activation of pp70S6k. In this case, inhibition appears to occur at least two points in this signalling path. Like rapamycin, PKA appears to act downstream of cPKC-mediated pp70S6k activation, and like wortmannin, PKA antagonizes IL-2-dependent activation of PI3K. The results with rapamycin and wortmannin are of added interest since the yeast and mammalian rapamycin targets resemble PI3K in the catalytic domain.

HAEMOLYMPH AND TISSUE TITRES OF ACHETAKININS IN THE HOUSE CRICKET ACHETA DOMESTICUS: EFFECT OF STARVATION AND DEHYDRATION

Achetakinin-like immunoreactive material in tissues and haemolymph of adult male crickets was quantified by radioimmunoassay. Achetakinin-like material was found in the brain, suboesophageal ganglia and the thoracic and abdominal ganglia, but the largest amount was within the retrocerebral complex. A Ca2+-dependent release of achetakinin-like immunoreactive material was demonstrated from retrocerebral complexes incubated in vitro in saline containing a high concentration of K+. The concentration of achetakinin-like material in haemolymph from fed crickets was estimated to be 2.8 nmol l-1 and increased more than 10-fold in insects starved for 48 h without access to water. The presence of achetakinin-like material in haemolymph suggests that these peptides are released in vivo and function as circulating neurohormones.

PDGF- and insulin-dependent pp70S6k activation mediated by phosphatidylinositol-3-OH kinase

Platelet-derived growth factor receptor (PDGF-R) phosphorylation at tyrosines 740/751 and insulin receptor phosphorylation of insulin receptor substrate-1 effects the recruitment and activation of phosphatidylinositol-3-OH kinase (PI(3)K). Changes in PI(3)K activity correlate with cell growth but its downstream signal transducers are unknown. Activation of the 70/85K S6 kinases (pp70S6k) by serine phosphorylation results in 40S ribosomal protein S6 phosphorylation and is important for G1 cell-cycle transition in a variety of cells. Although receptor tyrosine kinases activate the microtubule-associated protein kinase cascade through SH2-/SH3-adaptor proteins, Sos and c-Ras, it is unclear how tyrosine kinases are coupled to the pp70S6k phosphorylation cascade. Here we report that PI(3)K mediates PDGF or insulin receptor signalling to pp70S6k. PI(3)K-mediated activation of pp70S6k is independent of conventional protein kinase C isoforms. Additionally, rapamycin blocks pp70S6k activation by all mitogens, without inhibiting PI(3)K, and acts downstream in this signalling system.

Retrospective population-based analysis of the dose-response (fecal fat excretion) relationship of orlistat in normal and obese volunteers

Orlistat, an inhibitor of gastrointestinal lipases, limits the absorption of ingested fat and could become a potential treatment for obesity. This analysis was performed to elucidate the relationship between orlistat dose and intensity of inhibition of dietary fat absorption (assessed by measuring fecal fat excretion). In 11 phase I double-blind, placebo-controlled, parallel-group randomized studies, a total of 171 subjects received oral daily doses that ranged from 30 to 1200 mg orlistat or matching placebo three times a day for 9 to 10 days. The results of the daily mean fecal fat excretion percentage (relative to ingested fat) were correlated to the orlistat daily dose. A simple maximum-effect model that included a basal value was used to fit the dose-response relationship for all evaluable subjects. The mean maximum percentage of ingested fat excreted in the feces was approximately 32% during orlistat administration compared with 5% during placebo administration. The orlistat daily dose that produced 50% of the maximum effect was 98 mg/day. The model-fitting suggests the existence of a steep portion of the dose-response curve up to approximately 400 mg/day, with a subsequent tendency to plateau at higher doses. Such an analysis was instrumental in identifying appropriate doses to be used in therapeutic trials for weight loss in obese patients.

Endodermal sinus tumor: immunophenotypic expression of a carcinoma

A series of five endodermal sinus tumors was studied for their cytoskeletal and other phenotypic markers. They included 2 ovarian, 2 testicular, and 1 inguinal tumors. The cytoskeletal expression was also studied by gel electrophoresis and immunoblotting. Every tumor was diffusely and strongly immunostained for cytokeratin. By SDS-PAGE and immunoblotting, cytokeratins 8 & 18 were detected. Vimentin was focally coexpressed in 4 cases. The stroma was diffusely immunostained for vimentin. None of them expressed desmin, neurofilament, or glial filament protein. Desmoplakin was expressed only in one ovarian tumor. Alpha-fetoprotein and S-100 protein were also diffusely positive among the neoplastic cells; intracytoplasmic globules were especially strongly immunostained. These findings suggest that endodermal sinus tumors represent a group of pure malignant epithelial neoplasms, and may be regarded as primitive carcinomas.

Relationship between multiple biologic effects of rapamycin and the inhibition of pp70S6 protein kinase activity. Analysis in mutant clones of a T cell lymphoma

Rapamycin (RAP) inhibits several biologic responses in the YAC-1 T cell lymphoma, including the serum-driven proliferation and cyclin A mRNA expression, the induction of Ly-6E Ag expression by IFN, and the induction of IFN-gamma production by IL-1. RAP also suppresses the enzymatic activity of the 70 kDa S6 protein kinase (pp70s6k). To define the mechanistic relationship between these multiple effects of RAP, we have generated stable somatic mutants with altered sensitivities to this drug. A first series of mutants, represented by the R19, 4R16, and 10R13 clones, showed markedly reduced sensitivity to the inhibitory effect of RAP on all biologic responses tested and on pp70s6k activity. Two other mutant types, R103 and R125, were both highly sensitive to RAP-mediated suppression of proliferation, of IL-1-induced IFN-gamma production, and of pp70s6k activity but differed in their Ly-6E response. This response was not affected by RAP in the R125 clone and was enhanced in the R103 clone. Therefore, the inhibitory effects of RAP on proliferation and IL-1-mediated IFN-gamma induction both appear associated with the inhibition of pp70s6k activity, whereas the modulation of Ly-6E induction is independent from the latter. Moreover, the cellular binding of [3H]dihydro-FK-506 was found to be blocked by RAP in all mutant types to the same extent as in wild-type YAC-1 cells, suggesting that the altered sensitivity to the effects of RAP in these mutants is not due to an inability of the drug to enter the cells or to interact with FKBP. Further biochemical characterization of the mutant cells described here is expected to help clarify the mechanisms of RAP action.

Relationship between multiple biologic effects of rapamycin and the inhibition of pp70S6 protein kinase activity. Analysis in mutant clones of a T cell lymphoma

Rapamycin (RAP) inhibits several biologic responses in the YAC-1 T cell lymphoma, including the serum-driven proliferation and cyclin A mRNA expression, the induction of Ly-6E Ag expression by IFN, and the induction of IFN-gamma production by IL-1. RAP also suppresses the enzymatic activity of the 70 kDa S6 protein kinase (pp70s6k). To define the mechanistic relationship between these multiple effects of RAP, we have generated stable somatic mutants with altered sensitivities to this drug. A first series of mutants, represented by the R19, 4R16, and 10R13 clones, showed markedly reduced sensitivity to the inhibitory effect of RAP on all biologic responses tested and on pp70s6k activity. Two other mutant types, R103 and R125, were both highly sensitive to RAP-mediated suppression of proliferation, of IL-1-induced IFN-gamma production, and of pp70s6k activity but differed in their Ly-6E response. This response was not affected by RAP in the R125 clone and was enhanced in the R103 clone. Therefore, the inhibitory effects of RAP on proliferation and IL-1-mediated IFN-gamma induction both appear associated with the inhibition of pp70s6k activity, whereas the modulation of Ly-6E induction is independent from the latter. Moreover, the cellular binding of [3H]dihydro-FK-506 was found to be blocked by RAP in all mutant types to the same extent as in wild-type YAC-1 cells, suggesting that the altered sensitivity to the effects of RAP in these mutants is not due to an inability of the drug to enter the cells or to interact with FKBP. Further biochemical characterization of the mutant cells described here is expected to help clarify the mechanisms of RAP action.

Rudimentary polydactyly

A case of rudimentary polydactyly on the radial aspect of the thumb of a 4-year-old male was examined. Histologic examination revealed hyperkeratosis and acanthosis in the epidermis and large numbers of nerve bundles in the dermis. With immunoperoxidase staining for S-100 protein, the nerve corpuscles were positively stained. We think that rudimentary polydactyly is a kind of congenital traumatic neuroma and that the possible cause may be intrauterine amputation.

Alterations of the stalk of the influenza virus neuraminidase: deletions and insertions

The neuraminidase (NA) of influenza viruses cleaves sialic acids from receptors, prevents self-aggregation and facilitates release of virus during budding from host cells. Although the structure and function of the globular head of the influenza virus NA has been well studied, much less is known about the stalk of the NA, the region between the viral membrane and the globular head. Applying a reverse genetics system, we altered the stalk of the influenza A/WSN/33 virus NA by making deletions, insertions and mutations in this region of the gene. Our data show that the length of the NA stalk can be variable. Deletions of up to 28 amino acids and insertions of up to 41 amino acids in the stalk region did not abolish formation of infectious progeny virus. The data also indicate that the cysteine at position 76 is essential for formation of infectious virus, and that deletions beyond the cysteine did not result in infectious virus. Interestingly, shortening of the length of the stalk region by 28 amino acids resulted in a virus with a markedly reduced growth rate in MDCK cells as compared to that in MDBK cells. An insertion of 41 extra amino acids into the stalk did not significantly interfere with viral growth in MDCK or MDBK cells, which suggests that the stalk region would tolerate the introduction of long foreign sequences.

Psychological effects of participation and nonparticipation in a placebo-controlled zidovudine clinical trial with asymptomatic human immunodeficiency virus-infected individuals

Psychological effects of participation in Protocol 019, a zidovudine placebo-controlled clinical trial, were investigated. Forty-six Protocol 019 subjects and 27 control asymptomatic human immunodeficiency virus-seropositive subjects were assessed at entry, 2 months, 6 months, and after trial modification. At baseline there were no psychological differences. Most Protocol 019 and control subjects were depressed on at least one psychological measure; fewer were anxious. Both groups had improvement over time. By 6 months, Protocol 019 subjects had decreased Beck Depression Inventory (BDI) scores, state anxiety, stress reaction, and symptoms of depression and anxiety. Controls had decreased scores on only the BDI. Over time, the percentage meeting modified DSM III-R criteria for anxiety decreased in both groups and the proportion of Protocol 019 subjects meeting DSM III-R depression criteria decreased. After protocol modification, study subjects were less depressed and distressed than controls. Protocol 019 subjects reduced depression symptoms but controls did not. Clinical trial participation was not deleterious and may have yielded some relative psychological benefit.

Analysis of differential HLA-DQB expression in autologous B cell lines

Class II major histocompatibility complex genes are differentially expressed during cellular activation and differentiation, often in a locus-specific manner. We investigated the differential expression of the HLA-DQB gene, using B cell lines LAZ221 and LAZ388: LAZ221, derived from an early B cell leukemia, expresses HLA-DR but not HLA-DQ: LAZ388, the autologous Epstein-Barr virus-transformed B cell line, expresses both DR and DQ. Transfection experiments demonstrate differential function of class II gene upstream regulatory regions in the two lines, which correlates with differential class II gene expression. Using gel retardation and DNase I footprint assays, we demonstrate that absence of DQB gene expression is associated with characteristic nuclear protein-binding interactions in the proximal DQB gene upstream regulatory region. These interactions are visualized as DNA-protein complexes that are seen with nuclear proteins from the DQ-negative cell line, LAZ221, and involve consensus promoter Y box and W box elements, as well as novel upstream sites. Transcriptional regulatory proteins that differ in these autologous B cell lines may be stage-specific factors involved in the developmental regulation of HLA genes.

Synergistic effect of pyrophosphate and sodium dodecyl sulfate on periodontal pathogens

Our previous studies have shown that pyrophosphate (PPi), the anticalculus component of tartar-control dentifrices, inhibits the growth of organisms associated with coronal and root surface caries. The purposes of this investigation were to: 1) determine if periodontal pathogens are similarly susceptible to the growth-inhibitory properties of PPi; and 2) determine if combinations of pyrophosphate-sodium dodecyl sulfate (PPi-SDS) inhibit growth synergistically. Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Eikenella corrodens, and Campylobacter rectus (formerly Wolinella recta) were cultured in appropriate enriched media under anaerobic conditions. Inhibition assays were performed in tubes containing media supplemented with PPi and/or SDS. A range of concentrations of PPi and SDS in 2-fold increments was employed, with each concentration assayed in triplicate. Minimal inhibitory concentration (MIC) analyses revealed all of the bacteria were susceptible to PPi and SDS, with MICs of 0.67% (25 mM) and 0.01% w/v respectively. Combination studies with PPi-SDS showed much greater growth inhibition against P. gingivalis and A. actinomycetemcomitans than achieved with the agents individually. Determination of fractional inhibitory concentration indices indicated a synergistic growth-inhibitory effect. Under the constraints of the conditions employed, these studies demonstrate the efficacy of PPi-SDS combinations in inhibiting the growth of periodontal pathogens. It is conceivable that these compounds may have clinical benefit as a subgingival irrigant.

Rapamycin selectively inhibits interleukin-2 activation of p70 S6 kinase

The macrolide rapamycin induces cell cycle G1 arrest in yeast and in mammalian cells, which suggests that an evolutionarily conserved, rapamycin-sensitive pathway may regulate entry into S phase. In mammals, rapamycin inhibits interleukin-2 receptor-induced S phase entry and subsequent T-cell proliferation, resulting in immunosuppression. Here we show that interleukin-2 selectively stimulates the phosphorylation and activation of p70 S6 kinase but not the erk-encoded MAP kinases and rsk-encoded S6 kinases. Rapamycin completely and rapidly inhibits interleukin-2-induced phosphorylation and activation of p70 S6 kinase at concentrations comparable to those blocking S phase entry of T cells (0.05-0.2 nM). The structurally related macrolide FK506 competitively antagonizes the actions of rapamycin, indicating that these effects are mediated by FKBP, which binds the transition-state mimic structure common to both rapamycin and FK506 (refs 4, 6, 9-11). The selective blockade of the p70 S6 kinase activation cascade by the rapamycin-FKBP complex implicates this signalling pathway in the regulation of T cell entry into S phase.

Rapamycin-FKBP specifically blocks growth-dependent activation of and signaling by the 70 kd S6 protein kinases

The macrolide rapamycin blocks cell cycle progression in yeast and various animal cells by an unknown mechanism. We demonstrate that rapamycin blocks the phosphorylation and activation of the 70 kd S6 protein kinases (pp70S6K) in a variety of animal cells. The structurally related drug FK506 had no effect on pp70S6K activation but at high concentrations reversed the rapamycin-induced block, confirming the requirement for the rapamycin and FK506 receptor, FKBP. Rapamycin also interfered with signaling by these S6 kinases, blocking serum-stimulated S6 phosphorylation and delaying entry of Swiss 3T3 cells into S phase. Neither rapamycin nor FK506 blocked activation of a distinct family of S6 kinases (RSKs) or the MAP kinases. These studies identify a rapamycin-sensitive signaling pathway, argue for a ubiquitous role for FKBPs in signal transduction, indicate that FK506-FKBP-calcineurin complexes do not interfere with pp70S6K signaling, and show that in fibroblasts pp70S6K, not RSK, is the physiological S6 kinase.

Lactoferrin gene promoter: structural integrity and nonexpression in HL60 cells

Lactoferrin is a member of the transferrin family of iron-binding proteins. It is found in several glandular epithelial tissues and human neutrophils, where it is localized to secondary granules. To examine the mechanisms controlling lactoferrin gene expression in neutrophils and defects in its expression in acute leukemia, we have cloned a lactoferrin cDNA from a chronic myelogenous leukemia library, and used it to obtain genomic clones representing the chromosomal lactoferrin gene. Using polymerase chain reaction, primer extension, and S1 analysis, we have identified the 5' end of the lactoferrin mRNA. We have defined a putative promoter region for the gene, and characterized its first two exons. In addition, we have examined the structure of these regions in DNA from HL60 cells. HL60 is a leukemic cell line that undergoes phenotypic neutrophil maturation on exposure to dimethyl sulfoxide (DMSO). However, the cells cannot be induced to express any secondary granule protein genes. We have shown that the 5' end of the lactoferrin gene, including the putative promoter region, is entirely normal in HL60. By Northern analysis, nuclear run-on studies, and primer extension assays we have shown that the gene is not transcribed in DMSO-induced HL60 cells. This supports the hypothesis that the defect in HL60 is an abnormality in the production or activity of a transacting regulator of lactoferrin gene expression.