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Biomedical subjects

W Bishop

Publications and source records attributed to W Bishop.

At least 19 recordsLinked to original sources
PubMed2001

The survivin:fas ratio in pediatric renal tumors.

BACKGROUND/PURPOSE: Apoptosis factors inducing or preventing cell death may govern the behavior of certain tumors. Fas is a pro-apoptotic receptor that induces cell death when bound by its ligand and is expressed at greater levels in pediatric renal tumors of good prognosis. Survivin is a novel inhibitor of apoptosis that is expressed in a cell cycle-dependent manner and is abundantly expressed in several tumors of unfavorable histology. This study evaluates the expression of survivin, as well as the prognostic value of the survivin:fas ratio in various types and stages of pediatric renal tumors. METHODS: Multiple apoptosis mRNA species were quantified by Rnase protection assay (RPA) in 32 pediatric renal tumors and adjacent normal kidney specimens before chemotherapy: Wilms' tumor (WT), n = 9; clear cell sarcoma (CCS), n = 4; rhabdoid tumor of the kidney (RTK), n = 5; mesoblastic nephroma (MN), n = 3 and normal kidney, n = 11. Western Blot and immunocytochemistry were used to confirm survivin protein expression in a selective specimen survey. Follow-up data were obtained on patient outcomes, and antiapoptotic to proapoptotic ratios were calculated and correlated with clinical recurrence of disease. RESULTS: Pediatric renal tumors express greater levels of both pro- and antiapoptotic factors than normal kidney. Survivin and fas appeared to be expressed differentially in the tumor specimens sampled. Five of 10 (50%) tumors that went on to recur expressed survivin, whereas survivin was present in only 2 of 11 (18%) nonrecurrent tumors. Conversely, only 2 of 10 (20%) tumors that recurred were fas positive, whereas 5 of 11 (45%) tumors that did not recur expressed fas. The mean survivin:fas ratio was significantly greater in the 10 tumors that went on to recur after treatment (4 RTK, 3 CCS, 3 WT), than in tumors not recurring (2.16+/-1.4 v 1.0+/-1.07; P =.01, Kruskal-Wallis test). The positive predictive value of tumor recurrence was 85.7% (CI: 42.1%, 99.6%) and the negative predictive value was 71.4% (CI: 41.9%, 91.6%) when a cutoff ratio of 1.6 was considered. CONCLUSIONS: The survivin:fas mRNA ratio is of prognostic value in its ability to predict recurrent disease in children undergoing treatment for pediatric renal tumors. In this series, a ratio of greater than 1.6 predicted recurrent disease with a high probability irrespective of clinical stage or pathologic type. Determining the survivin:fas ratio may guide treatment, follow-up and counseling of patients with pediatric renal tumors.

Apoptosis↗
PubMed2000

The modified Puestow procedure for complicated hereditary pancreatitis in children.

PURPOSE: The aim of this study was to evaluate the role of longitudinal pancreaticojejunostomy (modified Puestow procedure) in the treatment of complicated hereditary pancreatitis (HP) in children. METHODS: The authors reviewed their experience with the modified Puestow procedure for complicated HP in patients less than 18 years of age at a single tertiary care facility between 1973 and 1998. Main study outcomes included surgical morbidity and mortality, pre- and postoperative pancreatic function, number of hospitalizations, and percentile ideal body weight (IBW). RESULTS: Twelve patients (6 boys and 6 girls) with a mean age of 9.3 years were identified. Presenting diagnoses were abdominal pain (n = 10), failure to thrive (n = 4), pancreatic pleural effusion (n = 2), and pancreatic ascites (n = 1). Blood loss was greater in patients who underwent distal pancreatectomy to localize the duct (n = 6) than in those who underwent direct transpancreatic duct localization (n = 6; 29.1+/-6.8 v. 8.3+/-3.7 mL/kg; P = .03). Other complications in patients who underwent distal pancreatectomy included splenic devascularization requiring splenectomy (n = 1) and postoperative intraabdominal bleeding with subsequent left subphrenic abscess (n = 1). There was no surgical mortality. Five patients had steatorrhea preoperatively that resolved in 4 patients postoperatively and was well controlled in the fifth. Mean number of hospitalizations for pancreatitis in the 5 years after surgery were markedly less than in the 5 years preceding surgery (0.4+/-0.2 v. 3.5+/-0.5; P = .01, n = 9). Percentile ideal body weight tended to increase within the first postoperative year (24.6+/-6.8 v. 45.0+/-8.3; P = .07, n = 9), and by the third year this trend was clearly significant (27.0+/-7.2 v. 60.9+/-9.5; P = .01, n = 8). CONCLUSIONS: In children with complicated HP, the modified Puestow procedure improves the quality of life by improving pancreatic function, decreasing hospitalizations, and increasing the percentile ideal body weight. Direct pancreatic duct localization during the procedure had a lower morbidity rate than localization via distal pancreatectomy. It is our impression that surgery performed in the early stage of complicated disease may preserve pancreatic function.

Adolescent↗
PubMed2000

Overexpression of Fas-ligand by neuroblastoma: a novel mechanism of tumor-cell killing.

BACKGROUND/PURPOSE: Binding of Fas ligand (Fas-L) to the membrane-bound Fas receptor incites a series of intracellular events that results in programmed cell death or apoptosis. Although this apoptotic phenomenon plays a key role in down-regulating cytotoxic T cells, the authors have shown previously that pancreatic beta cells (bTC) overexpressing Fas-L paradoxically undergo accelerated rejection that is dependent on a Fas/Fas-L interaction. This study evaluates whether a neuroblastoma (NB) cell line manipulated to overexpress Fas-L undergoes similar destruction and whether tumor-specific protective immunity can be produced. METHODS: The authors transfected NB cells (SK-N-MC) with either mFas-L cloned into a pcDNA3.1/Zeo plasmid vector (NB/Fas-L) or with the vector alone (NB/control). Successful transfection of Fas-L was characterized by reverse transcription polymerase chain reaction (RT-PCR) and the ability of transfectants to induce apoptosis of Fas-sensitive T cells (Jurkat). Expression of Fas and Fas-L in untransfected NB clones was characterized by immunohistochemistry and RNase protection assay (RPA). Apoptosis was measured by FACScan analysis using an Annexin V assay. A total of 3x10(6) NB/control and NB/Fas-L cells were implanted subcutaneously into the hind leg of Balb/C SCID mice. Tumor-specific protective immunity was also tested in this model by inoculating mice with NB/Fas-L before implanting NB/control cells. RESULTS: Zeocin resistance and RT-PCR confirmed successful transfection of Fas-L into NB cells. Fas Ligand transfectants induced apoptosis in 17.6%+/-2.9% of Fas-sensitive T cells, whereas controls induced apoptosis in only 2.8%+/-1.2% (P = .01, n = 3). Although Fas appears to be constitutively expressed by NB in low amounts, introduction of Fas-L into NB cells did not induce suicide or affect tumor cell growth in vitro. In vivo, NB cells expressing Fas-L failed to grow in SCID mice (n = 3), whereas controls grew rapidly in all animals until death (n = 3). NB/control cells implanted into the opposite leg of mice that rejected initial NB/Fas-L transfectants also grew rapidly (n = 3) implying no protective immunity. CONCLUSIONS: Overexpression of Fas-L in NB clones targets such cells for rapid destruction even in immune compromised hosts, suggesting potential utility of Fas-L in combating NB. In this SCID mouse model, the observed effect is probably neutrophil mediated and does not provide tumor-specific protective immunity.

Animals↗
PubMed2000

Differential apoptosis gene expression in pediatric tumors of the kidney.

BACKGROUND/PURPOSE: Apoptosis, or programmed cell death, is essential in maintaining normal homeostasis of tissues. The process of apoptosis is controlled by numerous pro- and antiapoptotic factors. Variations in expression of such factors may account for some variations in tumor behavior. This study evaluates the expression of apoptotic mRNA species in pediatric renal tumors to determine whether a pattern of differential apoptosis gene expression correlates with tumor grade and type. METHODS: Twenty-five frozen tissue specimens were obtained from patients undergoing biopsy or resection of pediatric renal tumors before chemotherapy: Wilms' tumor stage II (WT-II, n = 4); Wilms' tumor stage III/IV (WT-III/IV, n = 4); clear cell sarcoma of the kidney stage III (CCSK, n = 2); rhabdoid tumor of the kidney stage III/IV (RTK, n = 4); and normal kidney (NK, n = 11). An RNase Protection Assay (RPA) was performed for 19 pro- and antiapoptotic mRNA species to detect and quantify expression (percentage of GAPDH expressed). Expression of specific mRNAs of interest were confirmed by Western Blot (WB). RESULTS: The expression of apoptotic mRNA species varied markedly between tumors. WT-II expressed greater amounts of proapoptotic receptor mRNA than CCSK or RTK. (Fas, 17.0+/-2.7% v. 2.5+/-0.5% v. 3.3+/-0.9%; P<.02; DR5, 77.0+/-8.8% v. 13.5+/-0.5% v. 27.0+/-4.8; P<.001; TNF-R, 71.3+/-17.0% v. 21.0+/-4.0% v. 29.0+/-5.0%; P<.07, respectively). Surprisingly, antiapoptotic factors (e.g., bcl-2 and bcl-xl) were not overexpressed in poor prognostic tumors (CCSK, RTK) compared with those with good prognosis (WT). Expression of TRAIL (a ligand for DR4 and DR5) was significantly lower in CCSK and RTK than in normal kidney (9.5+/-1.5% v. 56.1+/-10.1%; P = .01). CONCLUSIONS: Proapoptotic receptors are expressed at greater levels in good prognostic tumors, and this finding is compatible with their clinical behavior. Knowledge of differential apoptotic gene expression is of potential value in predicting prognosis and treating such tumors with targeted ligands.

Apoptosis↗
PubMed1999

Overexpression of Fas ligand does not confer immune privilege to a pancreatic beta tumor cell line (betaTC-3).

BACKGROUND: Fas ligand (Fas-L) is thought to provide immune privilege to specific tissues and tumors by inducing an apoptotic signal of cytotoxic T cells expressing its Fas receptor. Purpose. The purpose of this work was to evaluate whether an immortalized insulin-secreting cell line (betaTC-3) gains immune privilege by inducing overexpression of Fas-L. METHODS: A lipofection technique was used to transfect a betaTC-3 tumor cell line with a plasmid (pcDNA3.1/Zeo) carrying the Fas-L gene and a zeocin resistance gene. Insertion of Fas-L into betaTC was characterized by reverse transcription polymerase chain reaction (RT-PCR) and the ability of transfectants (betaTC-3/Fas-L) to induce apoptosis of Fas-sensitive T cells. Transfectants and control cells were tested for insulin secretion following which 1 x 10(6) insulin-secreting betaTC-3 and betaTC-3/Fas-L cells were subcutaneously implanted into syngeneic, allogeneic, and Fas mutant (lpr) syngeneic mice. Survival of the insulin-secreting cells was then determined by monitoring serum glucose levels in recipients. RESULTS: Successful transfection of vector resistance gene was achieved in the transfected betaTC-3 cells, which was confirmed by zeocin resistance. RT-PCR in resistant Fas-L clones confirmed the transcription of Fas-L, which was absent in controls. Fas-L transfectants induced 20 +/- 4.2% apoptosis of Fas-sensitive T cells, while controls induced 3.47 +/- 2.3% by flow cytometry (P = 0.04, n = 3). Insulin secretion was equivalent in both betaTC-3 and betaTC-3/Fas-L cells. Syngeneic mice implanted with control betaTC-3 cells died within 3 weeks from hypoglycemia due to overgrowth of betaTC-3 tumor. Implanted Fas-L transfected betaTC-3 cells were killed and had no effect on glycemic status except in Fas mutant hosts, where tumors formed in two of three mice. CONCLUSIONS: Despite the ability of transfected betaTC-3 cells to induce apoptosis of T cells in vitro, expression of Fas-L provided no immune privilege to these cells in vivo, but paradoxically induced killing of betaTC-3 cells even in syngeneic hosts.

Animals↗
PubMed1999

[Leydig cell function in experimental cryptorchism and varicocele in rats].

Leydig cells were isolated from testes of normal, cryptorchid and induced- varicocele rats. These cells were counted and coincubated with and without human Chorionic Gonadotropin (hCG) during 3 hours; thereafter, steroids were measured in the incubation media. Cryptorchid animals showed the lowest number of Leydig cells, the highest Progesterone response to hCG, a slight increment of testosterone and a decrease of estradiol. On the contrary, both left and right testes from varicocele induced rats showed a higher cell number (per g of tissue), lower progesterone response, slightly higher response testosterone and lower testosterone response. These results demonstrate that these conditions of testicular hyperthermia do not affect the number and function of Leydig cells to the same degree. This may be due to differences in the testicular temperature reached with each procedure.

Animals↗
PubMed1998

[Effects of dehydroepiandrosterone on blood cells of the rat].

The effects of dehydroepiandrosterone (DHEA) on haemoglobin, hematocrit and white cell counts values were studied in male and female rats, castrated rats and pregnant rats. After 5 continuous days of DHEA administrated subcutaneously (80 mg/kg/d; body w.) haemoglobin and hematocrit values were similar those values obtained before the treatment. White cell counts were reduced (40%) in female no castrated rats due to a significantly lymphopenia. The white cell counts were increased in castrated rats and with DHEA administration there were reduced to the initial values. Estradiol treatment had the same effect as DHEA on castrated rats. These data suggest that DHEA administrated to castrated or sexually active male and female rats affects the white cells without important effects on red blood cells.

Adjuvants, Immunologic↗
PubMed1996

Acute effects of digitalis and enalapril on the neurohormonal profile of chagasic patients with severe congestive heart failure.

Chagasic patients with congestive heart failure are usually treated with digitalis and converting enzyme inhibitors. According to the neurogenic and dysautonomic theories, chagasic patients would not benefit from these drugs. To clarify this controversial issue, we have studied patients with congestive heart failure and suspected Chagas' heart disease. All patients received intravenous methyl-digoxin for 24 h and oral enalapril for 96 h. Blood samples for plasma norepinephrine, aldosterone and renin were taken at baseline, after acute digitalization and following enalapril. Based on the serology for Chagas' disease, the patients were divided into non-chagasic and chagasic patients. In the chagasic group three patients were in functional class III and 3 were in functional class IV. In the non-chagasic group five patients were in functional class III and 2 were in functional class IV. Both groups had a marked and quantitatively similar degree of neurohormonal activation. All patients improved at least one functional class and lost more than 5 kg of body weight with treatment. The chagasic patients had a statistically significant reduction in plasma norepinephrine (2262 +/- 1407 to 865 +/- 390, P < 0.008, pg/ml, M +/- S.D.), plasma aldosterone (330 +/- 168 to 155 +/- 75, P < 0.01, pg/ml, M +/- S.D.) and plasma renin activity (14 +/- 13 to 2 +/- 1.6 ng/ml per h, M +/- S.D., P < 0.05), with digitalis. Following enalapril, norepinephrine and aldosterone there was a further but non-significant reduction, when compared to postdigitalis values. These results indicated that chagasic patients do benefit from digitalis and enalapril. Furthermore, the prominent and significant reduction in all three neurohormones suggest that the parasympathetic and sympathetic systems of these chagasic and non-chagasic patients, are responding to the neuromodulatory effects of digitalis and enalapril.

Aldosterone↗
PubMed1996

Cytokines regulate apolipoprotein B secretion by Caco-2 cells: differential effects of IL-6 and TGF-beta 1.

A variety of cytokines are found in the intestinal mucosa of individuals with inflammatory diseases. The potential role of cytokines in mediating lipoprotein assembly and secretion in the human intestinal cell line, Caco-2, was investigated. Interleukin-1 beta, interleukin-6 (IL-6), and tumor necrosis factor-alpha all decreased the basolateral secretion of apolipoprotein B (apo B), with IL-6 being the most potent. IL-6 was also found to inhibit triacylglycerol secretion. In contrast, transforming growth factor-beta 1 (TGF-beta 1) increased the secretion of apo B and triacylglycerol. In pulse-chase experiments, IL-6 decreased the rate of synthesis and secretion of apo B-100 and apo B-48 without altering the rate of apo B degradation, whereas TGF-beta 1 increased the rate of synthesis and secretion of apo B-100 and apo B-48. Degradation of apo B was also not affected by TGF-beta 1. The abundance of apo B mRNA in cells incubated with IL-6 was decreased, whereas cells incubated with TGF-beta 1 had higher levels of apo B mRNA. In conditions of small intestinal inflammation, cytokines could contribute to the observed malabsorption of fat and other nutrients by the small intestine.

Animals↗
PubMed1996

[Leydig cell function in hyper- or hypoprolactinemic states in healthy men].

In the present investigation the function of the Leydig cells, as the response of gonadal steroids to the injections i.m. of 2000 UI of hCG, was studied in 11 normal men, before and after the induction of hyper or hypoprolactinemia with sulpiride and bromocriptine treatments respectively. The normal response to hCG, showed an increment of serum estradiol concentration 24 h and another of serum testosterone 72 h after the administration of the gonadotropin. The serum FSH concentration decreased during the test. An increase of serum LH levels was observed in the hypoprolactinemic state, but the increment of estradiol was lower after injection of hCG. On the other hand, the hyperprolactinemia induced a low basal level of testosterone with a higher response of this steroid to hCG. The results suggest that hyperprolactinemia interfers the estradiol synthesis by Leydig cells while the loss of the trophic effect of prolactin on gonadal steroidogenesis, as seen in hypoprolactinemia produces a decrease of basal testosterone levels without any alteration of the response of this steroid to hCG. We conclude that prolactin plays an important role in the steroidogenesis of Leydig cells in normal men.

Adult↗
PubMed1992

[In vitro stimulation of Leydig cells with human chorionic gonadotropin in adult rats of different ages].

We studied the functional reserve of Leydig cells in adult rats of different ages in vitro. Suspensions of Leydig cells after digestion by collagenase were stimulated with Human Chorionic Gonadotropin (hCG) during different times (1, 3 and 5 hours). We observed that response of Leydig cells, expressed by the testosterone concentration in the culture medium, showed a similar pattern in all studied group, and the highest response was seen at three hours of incubation. On the other hand, the testosterone response to hCG varied with age of animal. Thus, it was higher in the group of 14 months old (middle aged) than young animals (5 month old) and decreased in old animals (21 months old). These results suggest that a primary testicular lesion occurs with aging.

Age Factors↗
PubMed1985

Attempts to isolate N-nitroso compounds from Chinese-style salted fish.

Various types of salted fish have been collected from Hong Kong and analyzed for volatile nitrosamines and bacterial mutagenicity. Both of these parameters were low in the samples as collected. Exposure of these samples to nitrite yields substantial quantities of nitrosamines and mutagenic activity.

Animals↗
PubMed1984

Inhibition of in vitro human chorionic gonadotropin-stimulated testosterone production in testis and of ovulation in the rat by charcoal-treated rat testicular extract.

Previously, we described the presence of a factor obtained from a 105,000 X g supernatant of rat testis that was found to inhibit human chorionic gonadotropin (hCG) binding to gonadal receptors. In the present study, similarly prepared testicular extract was tested for its effects on in vitro hCG-stimulated testosterone production by isolated testis interstitial cells and for its effect on spontaneous ovulation in the rat. Incubation of interstitial cells with charcoal-treated extract significantly inhibited the steroidogenic response to hCG in a dose-related manner. This inhibition was also apparent after heating the extract for 10 min at 100 degrees C. Preincubation of the cells with charcoal-treated extract resulted in an inhibitory effect that was not readily reversed by subsequent addition of hCG, revealing an element of irreversibility in the mechanism of inhibition. A single i.p. injection of testicular extract given between 1430-1630 h of proestrus inhibited spontaneous ovulation in the rat. This effect was also observed after heating the extract for 10 min at 100 degrees C; in contrast, no significant effect was obtained with the injection of a similar dose of liver extract. Administration of 5 IU hCG after pretreatment with the testicular extract did not reverse the inhibitory effect on ovulation, indicating that this effect was probably not exerted at the hypothalamus-pituitary level. It is concluded that the aqueous testicular extract contains a factor able to antagonize the physiological events mediated by luteinizing hormone (LH)/hCG, and that this factor is consistent with the presence of an LH/hCG-binding inhibitory activity in rat testis.

Animals↗
PubMed1983

Plasma bupivacaine concentrations in children during caudal epidural analgesia.

Plasma bupivacaine concentrations were measured in 45 children, whose ages ranged from 4 months to 12 years, following administration of caudal epidural analgesia. Using 3 mg/kg of bupivacaine 0.25%, mean blood levels of 1.2-1.4 microgram/ml were reached, which are well within the limits of projected toxic levels. Simultaneous arterial and venous sampling showed a small but significant difference between these two sampling sites fo the first fifteen minutes.

Age Factors↗