Secondary School Athletic Trainers' Clinical Management Decisions of Low Socioeconomic Status Patients.

CONTEXT: Evidence suggests that negative social determinants of health (SDOH) and lower socioeconomic status (SES) contribute to health care disparities. Due to their accessibility in the high school setting, secondary school athletic trainers (SSATs) may encounter patients that are historically underserved in health care such as low SES patients. However, there is a significant gap in knowledge regarding how SES and SDOH may influence SSATs' clinical management decisions. OBJECTIVE: The purpose of this study was to describe SSATs' perceptions of how patient SDOH and SES influence clinical management decisions and to identify barriers to athletic healthcare. DESIGN: Cross-sectional study. SETTING: Online survey. PARTICIPANTS: NATA SSATs (6.7% response rate). MAIN OUTCOME MEASURE(S): SSATs were asked about their perceptions of patient SES and the SDOH (CVI = 0.83 for relevancy). Questions were ranked on a 4-point Liker scale on level of relevance and agreement. Data were summarized by means and standard deviations (SD), frequencies and proportions (%), and median scores. RESULTS: A total of 380 SSATs participated (years of experience mean=14.9±11.7 years). When providing care, most (71.3%) SSATs believed that their patient's health/health care access SDOH to be the most relevant of the 5 SDOH whereas the other 4 SDOH were less than 60% relevant. Most SSATs agreed/strongly agreed that patient SES impacts referral (67.4%) and the reliance on conservative treatment before referral (71.2%). SSATs identified patient/guardian compliance (70.2%) and type of health insurance (61.5%) as barriers to providing care to low SES patients. CONCLUSIONS: SSATs perceived health/health care access as the most relevant SDOH when providing care to low SES patients. When SSATs further considered the SES of patients, they identified all SDOHs as barriers to providing health care they were ill equipped to navigate as they delivered care and engaged in patient referral.

Water in Earth's Mantle: The Role of Nominally Anhydrous Minerals.

Most minerals of Earth's upper mantle contain small amounts of hydrogen, structurally bound as hydroxyl (OH). The OH concentration in each mineral species is variable, in some cases reflecting the geological environment of mineral formation. Of the major mantle minerals, pyroxenes are the most hydrous, typically containing approximately 200 to 500 parts per million H(2)O by weight, and probably dominate the water budget and hydrogen geochemistry of mantle rocks that do not contain a hydrous phase. Garnets and olivines commonly contain approximately 1 to 50 parts per million. Nominally anhydrous minerals constitute a significant reservoir for mantle hydrogen, possibly accommodating all water in the depleted mantle and providing a possible mechanism to recycle water from Earth's surface into the deep mantle.

CYP2E1 and CYP4A as microsomal catalysts of lipid peroxides in murine nonalcoholic steatohepatitis.

Nonalcoholic steatohepatitis (NASH) and alcoholic liver disease have similar pathological features. Because CYP2E1 plays a key role in alcoholic liver disease with its ability to stimulate lipid peroxidation, we tested the proposal that CYP2E1 could also be a factor in the development of NASH. In a dietary model - mice fed a methionine- and choline-deficient (MCD) diet - liver injury was associated with both induction of CYP2E1 and a 100-fold increase in hepatic content of lipid peroxides. Microsomal NADPH-dependent lipid oxidases contributed to the formation of these lipid peroxides, and in vitro inhibition studies demonstrated that CYP2E1 was the major catalyst. To further define the role of CYP2E1 as an initiator of oxidative stress in NASH, Cyp2e1(-/-)mice were administered the MCD diet. CYP2E1 deficiency neither prevented the development of NASH nor abrogated the increased microsomal NADPH-dependent lipid peroxidation, indicating the operation of a non-CYP2E1 peroxidase pathway. In Cyp2e1(-/-) mice with NASH (but not in wild-type mice), CYP4A10 and CYP4A14 were upregulated. Furthermore, hepatic microsomal lipid peroxidation was substantially inhibited by anti-mouse CYP4A10 antibody in vitro. These results show that experimental NASH is strongly associated with hepatic microsomal lipid peroxidation. CYP2E1, the main enzyme associated with that process in wild-type mice, is not unique among P450 proteins in catalyzing peroxidation of endogenous lipids. We have now identified CYP4A enzymes as alternative initiators of oxidative stress in the liver.

Combined use of cyclosporin A and verapamil in modulating multidrug resistance in human leukemia cell lines.

This study describes the synergistic interaction of two biochemical modulators, cyclosporin A (CyA) and verapamil (Vp), in multidrug-resistant cells, the highly resistant and moderately resistant variants (CEM/VLB 1000 and CEM/VLB 100) of the parental drug-sensitive T-cell leukemia cell line CEM/CCRF. In the absence of either modulator, the 50% inhibitory concentration for Adriamycin in these cell lines was 270 +/- 10.6 (SD) micrograms/ml, 96 +/- 8.5 micrograms/ml, and 1.5 +/- 0.1 micrograms/ml, respectively. CyA and Vp dramatically reduced multidrug resistance in CEM/VLB 100 and CEM/VLB 1000 in a dose-dependent manner but had no effect on the sensitivity of the parental line to Adriamycin. At a CyA concentration of 8.3 mumol (10 micrograms/ml), the 50% inhibitory concentration of Adriamycin of CEM/VLB 1000 and CEM/VLB 100 fell to 5.9 +/- 0.9 micrograms/ml and 3.3 +/- 0.6 micrograms/ml, respectively. Similarly at a Vp concentration of 10 mumol the 50% inhibitory concentration of Adriamycin of CEM/VLB 1000 and CEM/VLB 100 fell to 23.7 +/- 3.7 micrograms/ml and 5.7 +/- 0.2 micrograms/ml, respectively. More importantly, CyA and Vp showed significant synergism when tested in combination in the moderately resistant line at concentrations normally seen after the clinical administration of these modulators. Synergy was also present when both drugs were tested in the highly resistant variant. These data indicate the need for in vivo studies, given the potential clinical importance of these observations.

Atypical multidrug resistance in a therapy-induced drug-resistant human leukemia cell line (LALW-2): resistance to Vinca alkaloids independent of P-glycoprotein.

Near diploid leukemic T-cells (LALW-2), exposed to cytotoxic drugs only as a consequence of therapy administered to the donor patient, have been maintained by serial xenograft in nude mice. In comparison with the leukemic line CCRF-CEM, using a growth inhibition assay, LALW-2 cells were resistant to Vinca alkaloids and actinomycin D (relative resistance, 200-fold or more), were slightly resistant to Adriamycin (relative resistance, 4-fold), and showed no resistance to daunorubicin or teniposide. By comparison, a vincristine-resistant CEM subline developed in our laboratory (CEM/VCR R) was resistant to all these agents by at least 30-fold. The VCR R subline served as a positive control, confirming the previously reported correlation between multidrug resistance and amplification of the P-glycoprotein gene. Comparison of CEM, CEM/VCR R, and LALW-2 cells establish that the P-glycoprotein gene was not amplified or overexpressed in the LALW-2 cells; neither could the gene product be detected by immunoblotting in extracts from these cells. The LALW-2 cells were further distinguished from CEM/VCR R cells due to the lack of increased vincristine efflux by the xenografted cells, an effect readily demonstrable in the CEM/VCR R cells. However, although LALW-2 cells efflux vincristine at the same rate as CCRF-CEM cells, the xenografted cells exhibited a reduced rate of vincristine accumulation. Uptake of daunorubicin by LALW-2 cells was not distinguished from that by CEM cells, consistent with similar 50% inhibitory dose levels for this drug in both cell populations, and differentiating both from CEM/VCR R cells. Thus, clinical resistance in this case appears to be an "atypical" form of multidrug resistance specifically distinguished by resistance to Vinca alkaloids and actinomycin D occurring in the absence of increased amounts of P-glycoprotein and manifesting decreased drug uptake.

Regulation of differentially spliced transcripts of acyl-CoA oxidase in the rat.

RNAse protection assay was used to distinguish between and to quantify alternatively spliced transcripts of acyl-CoA oxidase in liver, kidney and testis of control and methylclofenapate treated rats. The ratio of spliced transcripts (type I to II) was 1.18:1 in control liver RNA, with 130 and 110 molecules/cell, respectively, and 3.1:1 in treated liver RNA, with 2800 and 900 molecules/cell. The ratios were 1.6 and 2:1 in control and treated kidney, and 0.31:1 in testis. This is likely to be due to differential splicing, which is, therefore, regulated during peroxisome proliferation, and also in a tissue specific fashion.

A prospective randomized trial of single-agent versus combination chemotherapy in meningeal carcinomatosis.

Forty-four patients with documented meningeal carcinomatosis (small-cell lung carcinoma [SCLC], 29%; breast carcinoma, 25%) were treated in a prospective randomized trial with intrathecal methotrexate (MTX) 15 mg or MTX plus cytosine arabinoside (Ara-C) 50 mg/m2. Most patients received intrathecal hydrocortisone (HC) each treatment to minimize arachnoiditis. Overall response was 55%. Seven patients achieved complete response. Response to MTX was superior to combined MTX/Ara-C, but not significantly so (61% v 45%; P greater than .10). Response was more frequent if drugs were administered via Ommaya reservoir than by lumbar puncture (65% v 48%; P greater than .10). Concurrent radiotherapy to the CNS was associated with significantly better response (73% v 35%; P less than .05). Small-cell lung carcinoma patients showed the best response (69%). Overall median survival for the whole group was 8 weeks, but responders fared better than nonresponders (median survival, 18 v 7 weeks; P less than .05). Nausea and vomiting were the most common toxicities encountered (45%), but rarely proved limiting. An unusual, previously undocumented reaction to intrathecal HC was noted. MTX is moderately effective in nonleukemic meningeal carcinomatosis, but the addition of Ara-C does not appear to improve results. Pretreatment factors did not predict outcome in this trial.

Detection of P-glycoprotein in ovarian cancer: a molecular marker associated with multidrug resistance.

A multidrug resistance phenotype is frequently observed in animal and human cell lines selected for in vitro resistance to a single chemotherapeutic agent. Overexpression of a highly conserved cell-surface glycoprotein (P-glycoprotein) is consistently associated with this phenotype in these mutant lines. A monoclonal antibody against P-glycoprotein was used to examine tumor samples from five patients with advanced ovarian cancer for evidence of P-glycoprotein overexpression. High levels of P-glycoprotein were detected in samples from two patients suggesting that a multidrug resistance mutation may also occur in ovarian cancer. This finding has broad implications for the understanding of nonresponse to chemotherapy in a variety of human neoplasms, and may provide a rational explanation for failure of chemotherapy in treatment of advanced ovarian cancer.

P-glycoprotein in human sarcoma: evidence for multidrug resistance.

Overexpression of an immunologically conserved, cell-surface glycoprotein (P-glycoprotein) is consistently associated with multidrug resistance in cell lines in vitro. A preliminary survey of specimens from 12 solid tumor types in our laboratories indicates significant overexpression of P-glycoprotein in some sarcomas. When tested by immunoblotting with monoclonal antibodies directed against P-glycoprotein; tumors from six of 25 sarcoma patients displayed elevated levels of P-glycoprotein. Three of the sarcoma patients exhibiting P-glycoprotein had not previously been exposed to chemotherapy, implying that overexpression of this marker and possible concomitant multidrug resistance may not depend only on selection during prior drug treatments. The P-glycoprotein overexpression in the sarcoma specimens is evidence for the presence of multidrug resistant cells in these tumors; thus, our data suggest that this mode of resistance may have clinical significance in sarcoma patients.

Phase II trial of a 3-hour infusion of paclitaxel in previously untreated patients with advanced non-small-cell lung cancer.

PURPOSE: To determine the antitumor activity and toxicity of paclitaxel administered as a 3-hour infusion in patients with advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Fifty-one patients with advanced measurable or assessable NSCLC and performance status 0 to 2 who had not received prior chemotherapy were treated with paclitaxel 175 mg/m2 over 3 hours with premedication. Cycles were repeated every 3 weeks for a maximum of nine cycles. Most patients had prior radiotherapy (57%), extrathoracic metastatic disease (65%), and measurable disease (75%). Twenty-two percent had previously untreated stage III disease. RESULTS: The objective response rate was five of 51 (10%; 95% confidence interval, 3% to 21%). No subgroup with a higher response rate could be identified. There were no complete responses (CRs) and all responses lasted less than 5 months. Treatment was well tolerated with brief World Health Organization (WHO) grade IV neutropenia in only 16% of patients. Grade III/IV myalgia/athralgia occurred in 22% of patients. No significant hypersensitivity reactions occurred. CONCLUSION: The antitumor activity of this dose and schedule appears inferior to that reported in previously published phase II trials in NSCLC that used higher doses of paclitaxel infused over 24 hours, although confidence intervals for response overlap. Determining the optimal dose and schedule for using paclitaxel in NSCLC requires further investigation, and these results should caution against using shorter infusions outside appropriate clinical trials.

Leprosy in Britain: 50 years experience in Liverpool.

BACKGROUND: Leprosy is a chronic infection that presents with varying dermal and neurological symptoms, and which can lead to extensive disability and morbidity, often with accompanying social stigma. AIM: To review the patients presenting to the Liverpool School of Tropical Medicine (LSTM) between 1946 and 2003, looking specifically at country of birth and of infection, details of clinical presentation, diagnosis, management and reactions. DESIGN: Retrospective record review. METHODS: We retrieved all available clinical records for patients seen between 1946 and 2003 (n = 50), consisting of letters, hospital and LSTM casenotes, and some radiographs and photographs. Any history of tuberculosis or diabetes was recorded. RESULTS: Most patients (64%) were born in the Indian subcontinent, and most were thought to have contracted the disease there (62%). Features at presentation included anaesthetic skin lesions in 19 (36%), hypopigmentation in 15 (30%), and peripheral nerve enlargement in 25 (50%). Diagnoses were made by a combination of clinical data and biopsy (60%), and slit skin smears were positive for acid-fast bacilli in 61% of multibacillary patients. Initial presentation was with a leprosy reaction in five cases (10%), and reactions were documented in 42% of all patients. Treatments were varied, progressing from traditional Eastern medicine to the WHO-approved multidrug therapy in use today, with prophylaxis for children and close contacts. DISCUSSION: Leprosy remains an important diagnosis to consider in patients with a history of work or travel in the tropics, and is a diagnosis with far-reaching medical, social and emotional consequences.

Increased resistance and impaired maximal vasodilation in normotensive vascular beds of rats with coarctation hypertension.

To study the resistance of normotensive vascular beds in coarctation hypertension, we measured perfusion pressures of pump-perfused (blood), innervated, isolated hindlimbs of 12 rats (Group A) with 4 weeks of hypertension due to partial contriction of the abdominal aorta above the renal arteries, and of three control groups: 11 normotensive rats (Group B) with aorta sham-constricted, nine normotensive rats (Group C) with slight (5%) hindquarters atrophy due to partial constriction of the abdominal aorta below the renal arteries, and six rats with two-kidney, one clip Goldblatt hypertension (Group D). After aortic constriction, measured femoral arterial pressures in Group A rats remained normotensive. In hypertensive rats of Groups A and D, compared to normotensive Group B or C rats, hindlimb pressure-flow curves were displaced toward the pressure axis (p < 0.05). Compared to normotensive rats, drop in hindlimb resistance after acute local nerve section was increased in rats with coarctation hypertension. Residual resistance after maximal vasodilation with intraarterial sodium nitroprusside remained elevated in hypertensive rats of Groups A and D (p < 0.05), as compared to normotensive Group B or C rats; compared to Group B rats, this residual resistance in the coarcted rats of Group A was increased by 9%. Thus, in normotensive vascular beds of rats with chronic hypertension caused by aortic coarctation, resistance is elevated. The neurogenic component contributes to this high resistance, and structural vascular changes, indicated by impaired maximal vasodilation, may also contribute to the elevated resistance. It is most unlikely that these resistance changes are attributable to elevated hindlimb intravascular pressures.

Decreased intraocular pressure in dogs with one-kidney, one wrapped hypertension.

We examined the relationship of intraocular pressure and the development of one-kidney, one wrapped (perinephritic) hypertension in the dog. Conscious femoral arterial pressure (direct arterial puncture) and intraocular pressure (Schiotz tonometer) were measured weekly before and after the surgical induction of hypertension in 11 healthy male mongrel dogs and before and after unilateral nephrectomy in 15 normotensive control dogs. Preoperative mean arterial pressure (102 +/- 5 vs 99 +/- 8 [SD] mm Hg, hypertensive vs control dogs) and intraocular pressure (18.1 +/- 2.5 vs 17.7 +/- 2.1 mm Hg, hypertensive vs control dogs) were similar in both groups. In normotensive control dogs, mean arterial pressure and intraocular pressure averaged over the postoperative period (4-8 weeks) did not differ significantly from preoperative values. In contrast, during the same period arterial pressure significantly increased and intraocular pressure significantly decreased in hypertensive dogs (arterial pressure, 163 +/- 8 mm Hg; intraocular pressure, 11.9 +/- 4.0 mm Hg; p less than 0.001 for both values compared with corresponding values in control dogs). Intraocular pressure was inversely related to arterial pressure in hypertensive dogs (r = 0.56, p less than 0.01). These observations indicate that intraocular pressure decreases with the development of canine one-kidney, one wrapped hypertension. The mechanism of this decrease may be related to abnormalities in Na+,K+-adenosine triphosphatase activity found in this form of hypertension.

Long-term follow-up of a randomised trial of combined chemoradiotherapy induction treatment, with and without maintenance chemotherapy in patients with small cell carcinoma of the lung.

The toxicity and efficacy of concomitant chemotherapy and radiotherapy as induction therapy was evaluated in patients with previously untreated small cell carcinoma of the lung (SCLC), and in responding patients the value of maintenance chemotherapy was examined. 202 patients received induction chemotherapy with cisplatin and etoposide (EP), in combination with cranial and local radiotherapy. 85 patients (42%) developed grades III and IV myelosuppression, the main toxicity of induction treatment. Of the 154 responding patients, 129 were randomised to maintenance chemotherapy with vincristine, doxorubicin and cyclophosphamide (VAC) or no further treatment. The response rate for the limited disease patients (LD) was 87%, 62% achieving a complete response (CR) and the response rate for extensive disease patients (ED) was 68%, with 26% achieving a CR. 17 patients (11%) completed 10 courses of maintenance chemotherapy. 32 patients (57%) developed grade III and IV neutropenia. Median survival for all patients was 53 weeks (LD, 70 weeks; ED, 42.5 weeks). There was no significant difference in overall survival (OS) or disease-free survival (DFS) in the two randomisation arms. This study shows that EP combined with radiotherapy is an effective induction regimen in SCLC. Maintenance chemotherapy with VAC is not associated with increased survival but has significant toxicity after such induction treatment.

Meningeal carcinomatosis in small cell carcinoma of the lung.

Cerebral and meningeal metastases are increasingly important complications in small cell anaplastic carcinoma of the lung. In a study at this institution, 60 evaluable patients received intensive chemotherapy without prophylactic cranial irradiation or other prophylactic measures. The complete plus partial remission rate was 78 percent with a median survival of 49+ weeks (range eight to 106+ weeks) for those with a complete response and 18+ weeks (range six to 67 weeks) for those with a partial response, all of which are comparable to other reported series. In 11 patients (18 percent) meningeal carcinomatosis has developed. Forty-two percent of the patients with a relapse have exhibited meningeal carcinomatosis and in 27 percent of the patients with a relapse it was the only site of relapse. Cerebral metastases occurred in 27 percent of those who had a relapse, and in 12 percent this was the sole site of relapse. Simultaneous meningeal carcinomatosis and cerebral metastases occurred in 8 percent of the patients with a relapse. The median time to meningeal relapse was 27 weeks (range 12 to 60 weeks) compared with 25+ weeks (six to 106+ weeks) over-all, and the median survival was 28 weeks (range 14 to 82 weeks) compared with 25+ weeks (two to 106+ weeks) for the whole group with small cell carcinoma of the lung. Meningeal involvement in small cell carcinoma of the lung must now be considered a sanctuary site of equal importance to cerebral metastases. To prevent and treat this complication will necessitate evaluation of all available modalities, including cranial and spinal irradiation, intrathecal chemotherapy and systemic agents that readily cross the blood-brain barrier.

Vascular smooth muscle responses to endothelial autacoids in rats with chronic coarctation hypertension.

OBJECTIVE: To examine whether elevated intravascular pressure in chronic hypertension alters responses of vascular smooth muscle to agents of endothelial origin. METHODS: Coarctation hypertensive, sham normotensive control, and one-kidney, one clip hypertensive (1K1C) rats were used. Tail systolic, carotid and femoral arterial pressures were measured. Responses to histamine, endothelin-1 and the prostacyclin analog iloprost were evaluated in isolated helically cut strips of thoracic and abdominal aortas, with and without endothelium, from all groups. Responses to nitroglycerin were also evaluated in strips of abdominal aortas. RESULTS: Thoracic aortas from 1K1C and coarctation hypertensive rats, as well as abdominal aortas from 1K1C rats, but not abdominal aortas from coarctation hypertensive rats were exposed chronically to elevated arterial pressure. Endothelium-dependent maximal relaxation by histamine was significantly depressed in thoracic aortas from both groups of rats, as well as in abdominal aortas from 1K1C rats. Maximal relaxation and sensitivity to histamine were normal in abdominal aortas from coarctation hypertensive rats. Sensitivity to nitroglycerin was impaired in abdominal aortas from 1K1C rats but not in those from coarctation hypertensive rats; maximal relaxation to nitroglycerin was similar in all groups. Relaxation to iloprost was independent of the endothelium, observed only in thoracic aortas and impaired in hypertensive rats. Responses to endothelin-1 were similar in the groups. CONCLUSION: Vasorelaxation by histamine, iloprost and nitroglycerin are impaired in hypertension. The impaired relaxation by histamine results from exposure of the vascular endothelium to chronically elevated pressure. This impairment may be related to effects of high pressure in reducing the ability of the endothelium to produce endothelium-derived relaxing factor and inhibit cyclic GMP-dilator mechanisms.

Induction of cytochrome P450 and peroxisomal enzymes by clofibric acid in vivo and in vitro.

We have analysed the induction of microsomal and peroxisomal proteins and their RNAs after treatment of hepatocytes with the peroxisome proliferator, clofibric acid, in vitro and in vivo. After treatment of hepatocytes with 1 mM clofibric acid for 4 days, P450 4A1 RNA is induced 500-fold, and acyl-CoA oxidase and P450 2B1 280-fold, relative to control cultures. These RNAs are detectably induced after administration of 25 microM clofibric acid, and show a similar induction response with increasing doses of clofibric acid. Western blot analysis of the P450 4A and bifunctional enzyme (BFE) proteins showed that both were induced in parallel with increasing doses of clofibric acid, over a range of 25 microM-1 mM. The distribution of the induced proteins was examined by immunocytochemistry. Increasing doses of clofibric acid led to an increase in the average intensity of staining for both proteins throughout the hepatocyte population. There was, however, a graded variation between hepatocytes in the intensity of staining, both for P450 4A and BFE proteins. The heterogeneity in response of the hepatocyte population in vitro may be related to differential sensitivity of hepatocytes to induction in vivo. Therefore, rats were dosed with 0, 50 or 300 mg/kg of clofibric acid for 4 days by gavage, and the livers were examined by immunocytochemistry. After 50 mg/kg of clofibric acid, both P450 4A and BFE were induced mainly in zones 3 and 2 of the liver acinus. However, after 300 mg/kg of clofibric acid, staining for both proteins was strong and homogenous throughout the liver acinus. Thus, hepatocytes from zones 3 and 2 of the acinus are differentially responsive to induction by clofibric acid.

Effect of chronic high pressure on transient and tonic vascular contractions to serotonin in hypertension.

This study examined whether vascular contractions related to the extracellular or intracellular pools of calcium activated by serotonin are altered by high arterial pressure in chronic hypertension. Coarctation hypertensive (CH), sham normotensive control (C), and one-kidney, one-clip hypertensive rats (1K1C) were used. Tail systolic, carotid, and femoral arterial pressures were measured. Thoracic aortas from 1K1C and CH rats, as well as abdominal aortas from 1K1C rats, but not abdominal aortas from CH rats were exposed chronically to elevated arterial pressure. Isolated rings of thoracic and abdominal aortas from all groups were suspended in muscle baths for isometric force recordings. After cellular calcium depletion, dose-response curves to extracellular calcium, in the presence of 10(-5) mol/L serotonin, were unchanged in thoracic or abdominal aortas among the three groups. In the presence of submaximum levels of serotonin (2 x 10(-6) mol/L), thoracic and abdominal rings without endothelium and abdominal rings with endothelium from the three groups showed similar responses to extracellular calcium. Such responses were significantly depressed in thoracic rings with endothelium from CH and 1K1C rats. Transient contractions attributable to release of an intracellular calcium pool by 10(-5) mol/L serotonin were enhanced significantly in hypertensive thoracic and abdominal aortas from 1K1C rats, when the pool was loaded with 0.25, 0.5, 1.0, 2.0, or 4.0 mmol/L CaCl2, as well as in hypertensive thoracic aortas from CH rats when the pool was loaded with 1.0, 2.0, or 4.0 mmol/L CaCl2, but not in normotensive abdominal aortas from CH rats at any calcium-loading concentration. Similar results were observed in aortas from C, CH, and 1K1C rats loaded with 1.0 or 2.0 mmol/L CaCl2 and stimulated with 2 x 10(-6) mol/L serotonin. Endothelial removal had no effect on these calcium-release contractions in abdominal aortas from any group, but enhanced contractions in thoracic aortas of 1K1C rats. In rings loaded with 2.0 mmol/L CaCl2, 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate inhibited contractions attributable to release of cellular calcium stores to a similar extent in C, CH, and 1K1C rats. This study suggests that serotonin-stimulated intracellular calcium-dependent aortic contractions are enhanced by elevated pressure in renal hypertensive rats.

Comparison of western blot analysis and immunocytochemical detection of P-glycoprotein in multidrug resistant cells.

A sensitive immunocytochemical technique was developed to detect a 170,000 dalton cell membrane glycoprotein (P-gp) in cell lines resistant to vincristine and vinblastine with varying degrees of resistance. P-gp was shown very clearly using the C219 monoclonal antibody and immunocytochemical detection with either antialkaline phosphate or peroxidase-antiperoxidase with silver gold intensification. There was good correlation between the results obtained with immunocytochemical detection of P-gp in single cells and Western blot analysis. The technique is easily performed and can detect P-gp in relatively small numbers of cells that Western blot analysis could miss and is suitable for clinical application.

Specificity and sensitivity of immunocytochemistry for detecting P-glycoprotein in haematological malignancies.

AIMS: To determine the optimal working conditions of the alkaline phosphatase-antialkaline phosphatase (APAAP) method to establish a specific and sensitive assay for the detection of low numbers of MDR positive cells in patients with hematological malignancies. METHODS: Three monoclonal antibodies (C-219, JSB-1, MRK-16) were used for the detection of P-glycoprotein (P-gp) in cell lines and in samples from 43 patients with haematological malignancies. The results of the APAAP method were compared with western blotting for specificity and sensitivity. RESULTS: Excellent correlation was obtained between optimised APAAP and western blotting, except in the case of multiple myeloma. JSB-1 seemed to be the more useful monoclonal antibody for the APAAP which was more sensitive than western blotting in its ability to detect single P-gp positive cells. CONCLUSIONS: Methods for P-gp detection, as defined by multidrug resistant (MDR) cell lines, are not necessarily optimal and specific for clinical samples and may lead to higher false positive and negative results, according to the conditions and the monoclonal antibodies used.