Role of protein kinase C in the regulation of pumping activity in bovine mesenteric lymphatic vessels

We investigated the role of protein kinase C (PKC) in regulating the lymphatic myogenic response. Bovine mesenteric lymphatics were suspended in an organ bath with inflow and outflow ends cannulated. Input was provided from a reservoir filled with Krebs solution. The PKC activator phorbol 12-myristate 13-acetate (PMA) inhibited pumping significantly whether tested at a fixed pressure or as pressures were raised in 2 cm H2O increments (50% inhibition achieved at 4.6 x 10(-8)M. The inactive phorbol ester (4-alpha-PMA) had no effect. The specific PKC inhibitors calphostin (10(-9) to 10(-7)M) or chelerythrine (10(-8) to 10(-6)M) had no significant effect on pumping. However, chelerythrine (10(-6)M) was capable of reversing the inhibitory effects of PMA (5 x 10(-8)M). PKC activation is believed to inhibit nitric oxide (NO) production in some blood vessels, and previous work from our laboratory has demonstrated that NO is important in facilitating pumping activity in bovine lymphatics. We observed that sodium nitroprusside (sNP, 10(-7)M) or L-arginine (10(-4)M), reversed the depressor effects of PMA. These results suggest that PKC may not be involved in regulating the vessel's contractile response to pressure-induced stretch. However, the data with PMA suggest that these ducts contain PKC. PKC activation depresses lymphatic pumping and this effect may be mediated in part, by inhibition of NO.

Amoxicillin middle ear fluid penetration and pharmacokinetics in children with acute otitis media

BACKGROUND

Acute otitis media (AOM) is a common childhood infectious disease. The efficacy of antibiotic dosing regimens is usually assessed by antibiotic plasma pharmacokinetics or middle ear fluid (MEF) concentration at one or two time points. Viral coinfection in AOM reduced antibacterial efficacy of antibiotics.

OBJECTIVE

To determine amoxicillin MEF penetration and pharmacokinetics in bacterial and combined bacterial and viral AOM.

METHODS

Thirty-four children with AOM were enrolled, and MEF was collected by tympanocentesis for bacterial culture and viral studies. Nasal wash and venous blood were also obtained for viral culture and serologic studies, respectively. Subjects were treated with amoxicillin 40 mg/kg/day orally, divided in equal doses every 8 h. During the second visit (48 to 72 h later) the subjects, with the regular morning amoxicillin dose withheld, were given an oral amoxicillin dose of 25 mg/kg. Thereafter two blood samples and one MEF sample by tympanocentesis were collected from each child at selected times between 0.5 and 4.0 h after dosing for bacterial and viral studies and amoxicillin concentration determination by high performance liquid chromatography.

RESULTS

Eleven (37%) children had only bacterial infection, 6 (20%) had viral infection only, 6 (20%) had both bacterial and viral infections and in 7 (23%) neither bacterial nor viral pathogens were recovered. MEF bacterial culture was positive in 23 of 40 ears (57.5%) before treatment with amoxicillin (40 mg/kg/day) and was still positive in 4 of 38 ears (10.5%) after 2 to 3 days of treatment. Amoxicillin plasma concentration reached its peak at 1.0 to 1.5 h after a 25-mg/kg oral dose. The estimated MEF concentration peak occurred 3.0 h after the dose with MEF concentrations ranging from undetectable to 20.6 microg/ml and a mean of approximately 9.5 microg/ml. Geometric mean amoxicillin concentrations were lowest in virus-infected children (2.7 microg/ml), nearly the same in culture-negative samples from children without viral infection (2.9 microg/ml), higher in children with combined bacterial and viral infection (4.1 microg/ml) and highest in children with bacterial-only infection (5.7 microg/ml).

CONCLUSIONS

MEF amoxicillin penetration tended to be lower in children with viral infection. The current amoxicillin dosing recommendation of 40 mg/kg/day in three divided dose is inadequate to effectively eradicate resistant Streptococcus pneumoniae, particularly during viral coinfection. A dosing regimen of 75 to 90 mg/kg/day is recommended for AOM.

An ecological study of the effectiveness of mammography in reducing breast cancer mortality

OBJECTIVES

The purpose of this study was to determine the relation of screening mammography to breast cancer incidence and case fatality.

METHODS

In a sample of White female Medicare beneficiaries hospitalized in 1990-1991, age-adjusted breast cancer incidence and 2-year case fatality rates were estimated and compared with the frequency of mammographic screening from a population-based survey.

RESULTS

The average rates for incidence, case fatality, and mammography within 5 years in 29 states were 414/100,000, 18.8%, and 59.2%, respectively. There was a positive state-level correlation between mammography rates and incidence and an inverse correlation between mammography and case fatality.

CONCLUSIONS

High screening mammography rates in some states are associated with reduced breast cancer case fatality rates, presumably as a result of diagnosis of earlier stage cancers.

[Gene expression of thyrotropin receptor, thyroid peroxidase and thyroglobulin in autoimmune thyroid disease]

To investigate the expression of thyrotropin (TSH) receptor gene in autoimmune thyroid disease and the relationship with expression of thyroid peroxidase (TPO) and thyroglobulin (TG) genes, we examined TSH receptor, TPO and TG gene expression levels in 10 human thyroid tissues by Northern blot analysis, including 7 Graves disease (GD), 2 Hashimoto disease (HT), and 1 normal thyroid tissue. The expression levels of TSH-R gene and TG/TPO gene were different between GD group and HT group. In GD group, TSH-R gene expression was closely correlated to the expression of TPO gene (r = 0.882; P < 0.01) and TG gene (r = 0.723; P < 0.05). The gene expression levels in GD were higher than those in HT and control. In HT group, TPO, TG gene expression levels were relatively lower while TSH-R gene expression levels were still in normal range. The difference in gene expression is possibly related to the types of autoimmune antibodies and various dripping rates.

Lack of gender and racial differences in surgery and mortality in hospitalized Medicare beneficiaries with bleeding peptic ulcer

OBJECTIVE

Determine the relation of race and gender to outcome from bleeding peptic ulcer.

DESIGN

Retrospective cohort study.

SETTING

All acute care hospitals in the United States.

PATIENTS

A 100% sample of hospitalized Medicare beneficiaries older than 64 years (n = 82,868) with a primary discharge diagnosis of peptic ulcer with hemorrhage.

MEASUREMENTS AND MAIN RESULTS

Surgical treatment was performed in 6.9% of patients, 30-day mortality was 8.5%, and average length of stay was 9.4 days. Surgery was somewhat more common in men than women (7.3% vs 6.5%, p < .001), and in whites than African Americans (6.9% vs 6.3%, p < .001), but neither race nor gender was associated with surgery in multivariable analysis adjusting for potentially confounding factors. Mortality rates were similar in African Americans and whites (8.5%), and somewhat higher in men than women (10.7% vs 9.3%, p < .001). In multivariable analysis, there was no difference in mortality across gender and racial groups. Although unadjusted and adjusted lengths of stay were longer for African Americans and shorter for men, the differences were modest (i.e., 16% increase and 6% decrease in multivariable analysis, respectively, p < .0001).

CONCLUSIONS

In this national sample, there is no significant gender or racial difference in therapy and outcome for patients with hemorrhagic peptic ulcer. The findings raise the possibility that studies that have shown race and gender differences in management of coronary artery disease and cancer may not be generalizable to other common diagnoses.

Alendronate prevents cyclosporin A-induced osteopenia in the rat

Post-transplantation bone disease is an increasingly recognized clinical entity whose etiology is multifactorial. The immunosuppressant agent cyclosporine-A (CsA) has repeatedly been shown experimentally to induce a high-turnover osteopenic state. Alendronate (Alen.) is a new generation bisphosphonate having far greater antiresorptive potency than previous bisphosphonates. It inhibits osteoclast resorption in vitro and in vivo without adversely affecting bone mineralization. This study was designed to investigate whether alendronate could prevent CsA-induced osteopenia in the rat. Forty-eight 8-month-old male Sprague Dawley rats were randomized into four groups to receive the following for 28 days: (1) CsA vehicle (veh.) p.o. daily and alendronate vehicle subcutaneously (s.c.) twice/week, (2) CsA 15 mg/kg p.o. daily and Alen. veh. s.c. twice/week, (3) Alen. 70 micrograms/kg s.c. twice/ week and CsA veh. p.o. daily, and (4) CsA 15 mg/kg p.o. daily and Alen. 70 micrograms/kg s.c. twice/week. Rats were weighed and bled and serum was assayed serially for calcium, PTH, 1,25(OH)2vit.D, and osteocalcin. Tibiae were removed following sacrifice on day 28, after double demeclocycline and calcein labeling, for histomorphometric analysis. Treated groups were compared to the vehicle-treated control. We confirmed previous findings that CsA produces elevated 1,25(OH)2 vitamin D and serum osteocalcin levels. Alendronate treatment by itself decreased osteocalcin by day 28 and resulted in a marginal decrease in serum total calcium on day 14. The histomorphometry findings reconfirmed that the administration of CsA induces a state of high-turnover osteopenia. Alendronate prevented CsA's adverse effects, particularly in maintaining trabecular bone volume, presumably by decreasing bone remodeling. Alendronate would seem to hold therapeutic promise in post-transplantation bone disease.

High-performance liquid chromatographic analysis of amoxicillin in human and chinchilla plasma, middle ear fluid and whole blood

We extended the application of a sensitive high-performance liquid chromatography assay of amoxicillin developed in this laboratory for human plasma and middle ear fluid (MEF) to other sample matrices including chinchilla plasma or MEF and human and chinchilla whole blood with minor modification and validated the limit of quantitation at 0.25 microg/ml with a 50-microl sample size for human and chinchilla plasmas or MEFs. Amoxicillin and cefadroxil, the internal standard, were extracted from 50 microl of the samples with Bond Elut C18 cartridges. The extract was analyzed on a Keystone MOS Hypersil-1 (C8) column with UV detection at 210 nm. The mobile phase was 6% acetonitrile in 5 mM phosphate buffer, pH 6.5 and 5 mM tetrabutylammonium. The within-day coefficients of variation were 2.7-9.9 (n=4) and 1.7-7.2% (n=3) for chinchilla plasma and MEF samples, respectively; 2.8-8.1% (n=3) and 2.9-4.7% (n=3) for human and chinchilla whole blood, respectively. An alternative mobile phase composition for chinchilla plasma and MEF samples reduced the analysis time significantly.

Racial disparity in the incidence and case-fatality of colorectal cancer: analysis of 329 United States counties

In the United States, blacks have higher death rates from colon cancer than whites, and the survival disparity may be due in part to differences in screening programs and acute medical care in counties with a high concentration of blacks. We studied 148,947 Medicare beneficiaries with newly diagnosed colorectal cancer in 1989-1991 who resided in the 329 most populous counties in the United States to determine the relationship of race and county racial composition to cancer incidence and survival. Counties were divided into quartiles based on proportion of blacks in the population, and aggregate incidence and 2-year case-fatality rates were compared within and between quartiles. Within each quartile, the adjusted incidence rate for whites was consistently higher than that for blacks (P < 0.0001), and case-fatality rates were consistently lower among whites (P < 0.0001) for all but the quartile with the lowest proportion of blacks. Between quartiles, the incidence rates for both whites (P = 0.0001) and blacks (P = 0.008) decreased progressively, and case fatality rates increased progressively for both whites (P = 0.001) and blacks (P = 0.007) as the proportion of blacks increased. When counties were grouped into three different geographic areas, racial disparity in survival was observed in all regions. The variability between groups of counties in colon cancer incidence and mortality for both white and black patients may suggest differences at the county level in screening and treatment. However, consistent racial disparity within county quartiles may reflect persistent deficiencies in access to and quality of care for black patients.

The role of testosterone in cyclosporine-induced osteopenia

Our laboratory has demonstrated that the immunosuppressants Cyclosporin A (CsA) and tacrolimus (FK506), in vivo in the rat, produce a high-turnover osteopenia. CsA is known to decrease serum testosterone (Test) levels both in the rat and in human transplant patients. Less is known of FK506's effect on androgens. CsA-induced hypogonadism may contribute to the aforementioned bone loss because hypogonadism itself is a risk factor for osteoporosis and fracture. The aim of this study was to assess serum androgen levels following CsA and FK506 therapy and to see wether Test replacement therapy, in the form of 28-day controlled release subcutaneous pellet implants, could prevent CsA-induced osteopenia. Two experiments were conducted. In experiment I, four groups of 6-month-old male Sprague-Dawley rats received the following: (A) CsA vehicle and placebo pellet, (B) Test 15 mg pellet and CsA vehicle, (C) CsA 10 mg/kg and placebo pellet, (D) Test 15 mg pellet and CsA 10 mg/kg. In experiment II, two groups of rats received (E) FK506 vehicle and (F) FK506 4 mg/kg. CsA, FK506, and vehicles were given for 28 days by daily oral gavage. The rats were weighted and bled on days 0, 14, and 28. All rats received double fluorescent labeling, and on day 28 the tibiae were removed for histomorphometry. Whole blood was assayed for CsA and FK506 levels. Serum was assayed for total and free Test as well as for osteocalcin (BGP), blood urea nitrogen (BUN), creatinine, and calcium. Whole blood monoclonal CsA levels measured by fluorescent immunoassay were in the therapeutic range, while a drug concentration profile showed good absorption of FK506. Those rats receiving Test and FK506 lost weight, while those receiving CsA remained constant. BUN was only marginally elevated in the CsA-treated groups on day 28 (p < 0.05), while creatinine was unchanged. On day 28, total and free Test was significantly reduced in the CsA-treated rats versus control (p < 0.05), while Test replacement therapy maintained total Test levels above vehicle (p < 0.01) and free Test levels similar to vehicle on day 28. FK506 did not lower total or free Test levels. BGP levels were significantly increased in the CsA (p < 0.01) and FK506 (p < 0.001) groups on day 28. BGP in the groups receiving Test alone and in combination with CsA remained similar to vehicle. Histomorphometry confirmed CsA- and FK506-induced high-turnover osteopenia. The Test alone group marignally increased bone formation. Test replacement failed to prevent the CsA-induced bone loss. In conclusion, immunosuppressive doses of CsA, but not FK506, lowers serum total and free Test. Hypoandrogenemia does not seem to be a major factor in CsA-induced osteopenia because bone loss occurs despite Test replacement.

Mortality rates, hospital length of stay, and the cost of treating subarachnoid hemorrhage in older patients: institutional and geographical differences

The risk of disability and death and the cost of medical care are particularly high for patients with aneurysmal subarachnoid hemorrhage (SAH) who are 65 years of age or older. A retrospective analysis of 47,408 Medicare patients treated over an 8-year period was performed to determine whether a relationship exists between the mortality rate and surgical volume for older patients with SAH. The mortality rate, length of stay in the hospital, and cost of treatment for patients with SAH in California and New York state were also compared. The mortality rate was 14.3% for patients with SAH who were 65 years old or older and who were treated surgically in hospitals in which an average of five or more craniotomies were performed per year; in hospitals averaging between one and five craniotomies annually the mortality rate was 18.4%; and in those averaging less than one such operation per year the rate was 20.5% (trend p = 0.01). There was no difference in the mortality rate for patients in California versus the rate for those in New York. Surgically and medically treated patients, respectively, left the hospital an average of 6.7 and 5.1 days sooner in California than in New York. The unadjusted average reimbursement from Medicare to hospitals for surgically treated patients averaged $1468 more in New York than in California (p < 0.0001), but was equivalent for medically treated patients in the two states. The mortality rate in older patients who are treated surgically for SAH may be inversely correlated with the annual number of craniotomies performed for SAH in patients 65 years of age or older at a given institution. Hospital stays for patients with SAH are significantly shorter in California than in New York.

[A 20-year experience in surgical management of acute necrotizing pancreatitis]

From 1974 to 1994, 243 patients with acute necrotizing pancreatitis (ANP) proved by operation or CT scanning system were treated. The overall survival rate was 70.4%. In 1974-1987, the resection of necrosis was radical and as early as possible, and the main type of operation was subtotal pancreatectomy. The survival rate in this period was 61.3% (49/80). In 1988-1991, the treatment was changed into "individualization" i.e. for sterile pancreatic necrosis, conservative treatment was setected while infected pancreatic necrosis, necrosectomy was performed early. In this period, the survival rate of conservative treatment was 85.7% (6/7) and that of operative treatment 67.1%. The overall survival rate in was 68.5% (63/92). In 1991-1994, we insisted on late operation for the patients with necrosis and comprehensive management for all the patients with ANP. The survival rate of conservative treatment in this period was 100% (11/11) and that of operative treatment 80% (48/60). The overall survival rate was 83.1% (59/71). We conclude that comprehensive management combined with late operation for the patients with necrosis infected is a better strategy for the treatment of ANP.

A high-density screening format for encoded combinatorial libraries: assay miniaturization and its application to enzymatic reactions

A novel, miniaturized high-throughput screening format is described for assay of combinatorial libraries generated on beads. This approach, which is ideally suited to encoded libraries synthesized on beads, utilizes the photolytic cleavage of individual compounds into a high-density well array (>6500 wells within a standard 96-well microtiter plate footprint) with well volumes as low as 0.37 microl. As a model study, an encoded dipeptide library (324 members) acylated with isobutyl succinate was assayed using this format to search for potential inhibitors of matrilysin, a member of the matrix metalloproteinase superfamily. In situ release of compounds from solid support was accomplished by photochemical cleavage after beads and enzyme were distributed to the wells. After the addition of a fluorogenic substrate to the array, the extent of enzyme inhibition and identification of active compounds was quantitated by imaging of the fluorescence emission upon uv irradiation. The structure-activity relationship data generated from the identified inhibitors in this study corroborate previous findings, thus validating the utility of this approach as a means of high-throughput screening of bead-based libraries.

[Determination of Keganmin tablet with multi-wavelength K-factor spectrophotometry]

The contents of phenacetin, aminopyrine and caffeine in Keganmin tablet were determined simultaneonsly with multiwavelength K -factor spectrophotometry. The result is accurate and the method is rapid. The average recoveries and relative standard deviations of the analysis for phenacetin, aminopyrine and caffeine were 99.91%, 0.41%; 100.1%, 0.29%; 100.1%, 0.56%, respectively.

Combined flurbiprofen and cyclosporin-A does not attenuate bone loss and exaggerates renal impairment

Cyclosporine (CsA) is a potent immunosuppressant that has revolutionized the success of organ transplantation. Flurbiprofen (FB), a propionic acid derivative NSAID, has been demonstrated in vivo to reduce osteoclast numbers in normal rats. The aim of this experiment was to determine whether addition of FB to CsA-treated rats could prevent the bone changes associated with CsA therapy. Forty-eight 10-12-week-old male Sprague-Dawley rats were randomized to receive, daily for 28 days: (1) CsA vehicle p.o. plus FB vehicle sc; (2) CsA (15 mg/kg) p.o. plus FB vehicle sc, (3) CsA vehicle p.o. plus FB (1.5 mg/kg) sc; and (4) CsA (15 mg/kg) p.o. plus FB (1.5 mg/kg) sc. Rats were weighed and venous blood sampled at baseline, 14 days, and 28 days for determination of glucose, Ca+2, BUN, creatinine, PTH, osteocalcin, and 1,25(OH)2 vitamin D. Tibiae were removed following killing, after double labeling for histomorphometry. Body mass was significantly lower than control in all rats receiving CsA on days 14 and 28 while blood glucose was only elevated in the CsA alone group. Day 28 BUN and creatinine were significantly elevated in the CsA group and the combination of CsA and FB revealed an exacerbation of this trend. Vitamin D and osteocalcin were consistently increased in the CsA and CsA/FB groups. Bone histomorphometry showed evidence of trabecular osteopenia in CsA and CsA/FB groups. CsA alone resulted in elevated bone turnover. FB was unable to prevent the trabecular bone loss induced by CsA therapy. This experiment indicates no role for FB as a therapeutic option in CsA-induced bone disease at the given doses and duration of treatment by virtue of its lack of bone sparing ability and adverse renal effects when the two drugs are administered concurrently.

Selections from current literature: cholelithiasis, cholecystectomy and the risk of colorectal cancer

The study by Ekbom et al. clearly demonstrates that, overall, there is no increased risk of colorectal cancer following cholecystectomy. However, it is noted that women have a slight increase in the risk of proximal colon cancer following cholecystectomy. The reasons for this finding remain unclear. However, since this finding has been consistent in several studies, it is probably not an artifact, but a true association that may warrant further investigation. It is possible that the association noted between cholecystectomy and colorectal cancer is due not to the cholecystectomy, but to the reason why cholecystectomies are performed, namely the presence of gallstones. The cholecystectomy itself may simply be a surrogate for cholelithiasis, which may be a true risk factor for colorectal cancer. Excess secondary bile acids may be carcinogenic or the factors which cause the formation of cholelithiasis may also increase the risk for developing colorectal cancer. An answer to the separate question of whether excessive laparoscopic cholecystectomies are being performed, or whether newer indications make the increased number of laparoscopic cholecystectomies appropriate, remain outstanding. This new procedure, despite being cheaper than the open cholecystectomy, has resulted in greater utilization of the world's dwindling health care resources. In conclusion, the decision to perform a cholecystectomy should be made only with consideration of the patient's current medical condition. There is no need to be concerned about any future increased risk of colorectal cancer following a cholecystectomy.

[Study of heterogeneity in DNA ploidy and its clinical-pathological significance in esophageal squamous cell carcinoma]

In order to investigate the intratumoral DNA ploid heterogeneity in esophageal squamous cell carcinoma and its significance, nuclear DNA ploidy of 80 cases of squamous cell carcinoma of the esophagus were determined for multiple samples obtained from the same tumor, using a flow cytometry (FCM) technique. The results showed that: (1) DNA indeces ranged from 7.7-1.74, and the incidence of DNA aneuploidy was 88.8% (71/80) in this series; (2) of 80 cases, (47.5% 38 cases) showed intratumoral heterogeneity in DNA ploidy (3) the heterogeneity in DNA ploidy was related to the extent of wall penetration by tumor, the incidnce of lymph node metastasis and patient's prognosis, not to histological grades and size of tumor. The results from this study indicated that DNA ploidy heterogeneity may be a exact indicator in reflecting the biological characteristics of tumor and patient's prognosis than DNA aneuploidy from single site sampling.

Surgery for colorectal cancer: Race-related differences in rates and survival among Medicare beneficiaries

This study examined surgery for colorectal cancer among Medicare beneficiaries 65 years of age or older with an initial diagnosis in 1987 (n = 81 579). Black patients were less likely than White to undergo surgical resection (68% vs 78%), even after age, comorbidity, and location and extent of tumor were controlled for. Among those who underwent resection, Black patients were more likely to die (a 2-year mortality rate of 40.0% vs 33.5% in White patients); this disparity also remained after confounders had been controlled. The disparities were similar in teaching and nonteaching hospitals and in private and public hospitals. These data may indicate racially based differences among Medicare beneficiaries in access to and quality of care for colorectal cancer.

Site-directed mutagenesis of Cys324 and Cys331 in human cytosolic phospholipase A2: locus of action of thiol modification reagents leading to inactiviation of cPLA2

Human cytosolic phospholipase A2 contains two cysteines, cyS324 and cyS331, chemical modification of which using thiol modifying reagents abolishes the activity of the enzyme [Li et al. (1994) Biochemistry 33, 8594-8603]. To verify the functional importance of the two cysteine residues, site-directed mutagenesis has been used to create six mutations at positions 324 and 331. The mutant enzymes include C324A, C331A, C324Q, C331Q, C324R, and C331S. Complete loss of activity is observed for C331Q, whereas the other mutants have retained varying degrees of activity. These results show that neither CyS324 nor CyS311 is catalytically essential for the enzyme activity. Further chemical modification studies of the mutant enzymes by thiol-specific reagents suggest that modification of Cys331 is responsible for the complete loss of the enzyme activity. The possible roles of Cys324 and Cys331 are discussed.

Abdominal and vaginal radical hysterectomy among U.S. women aged 65 years and older

Unlike most European and Asian countries, radical vaginal hysterectomy (RVH) is not performed often in the United States, especially among older women. To examine the changes in RVH over the years, trends in hospital stay, hospital charges, and patient survival, we studied women aged 65 years and older undergoing RVH and compared them with patients receiving radical abdominal hysterectomy (RAH). During the study period there were a total of 288 RVH surgeries compared with 4,835 RAH surgeries. There were no significant changes in the number or proportion of RVH patients over 8 years (p = .50, trend test). On the average, RVH patients were significantly older and had shorter hospital stays. Among patients without cancer, there were no significant differences in the age, race, or survival of patients having either RVH or RAH. Similar results were obtained for patients with cancer.

Sensitive assay for measuring amoxicillin in human plasma and middle ear fluid using solid-phase extraction and reversed-phase high-performance liquid chromatography

We developed a sensitive assay to measure amoxicillin in human plasma and middle ear fluid (MEF) using solid-phase extraction and reversed-phase HPLC. Amoxicillin and cefadroxil, the internal standard, were extracted from 50-200 microliters of sample with Bond Elut C18 cartridges. The extract was analyzed on a 15 cm x 2 mm, 5 micron Keystone MOS Hypersil-1 (C8) column with UV detection at 210 nm. The mobile phase was 6% acetonitrile in 5 mM phosphate buffer (pH = 6.5) and 5 mM tetrabutylammonium. The average absolute recovery of amoxicillin and cefadroxil were 91.2 +/- 16.6% and 91.0 +/- 6.8%, respectively. The limit of quantitation was 0.125 microgram/ml with 200 microliters sample size. The linear range was from 0.125 to 35.0 micrograms/ml with correlation coefficients greater than 0.999. These analytic conditions produced a highly sensitive amoxicillin assay in human body fluids without derivatization.

Cerebral arterial aneurysm formation and rupture in 20,767 elderly patients: hypertension and other risk factors

Cerebral arterial aneurysms are common in the general population and their rupture is a catastrophic event. Considerable uncertainty remains concerning the conditions that predispose individuals to aneurysm formation or rupture. The role of systemic hypertension in aneurysm formation and rupture has been especially controversial. Demographic variables have rarely been addressed because of the small sample sizes in previous studies. The authors describe the demographics and prevalence of hypertension in 20,767 Medicare patients with an unruptured aneurysm and compared these to a random sample of the hospitalized Medicare population. The prevalence of hypertension in patients with unruptured aneurysms was 43.2% compared with 34.4% in the random sample. Patients who survived their initial hospitalization were separated into two groups: those with an unruptured cerebral aneurysm as the primary diagnosis and those with an unruptured cerebral aneurysm as a secondary diagnosis. Follow-up data for 18,119 patients were examined to determine the risk of subarachnoid hemorrhage (SAH) associated with age, gender, race, hypertension, insulin-dependent diabetes mellitus, and surgical treatment. For patients with an unruptured cerebral aneurysm as the primary diagnosis, hypertension was found to be a significant risk factor for future SAH (risk ratio: 1.46, 95% confidence interval (CI): 1.01-2.11), whereas surgical treatment (risk ratio: 0.29, 95% CI: 0.09-0.97) had a significant protective effect. Advancing age had a small but significant protective effect in both groups. Elderly patients identified with unruptured aneurysms are more likely to have coexisting hypertension than the general hospitalized population. In elderly patients hospitalized with an unruptured cerebral aneurysm as their primary diagnosis, hypertension is a risk factor for subsequent SAH, whereas surgical treatment is a protective factor against SAH.

Study of noncovalent enzyme-inhibitor complexes and metal binding stoichiometry of matrilysin by electrospray ionization mass spectrometry

Electrospray ionization mass spectrometry (ESI-MS) was used to study the noncovalent metallo-enzyme-inhibitor complexes of matrilysin (a matrix metalloproteinase of mass 18,720 u) under gentle experimental conditions and to determine the metal ion association stoichiometries in both the free enzyme and the complexes. The metal association stoichiometries of the free matrilysin were found to be highly sensitive to solution pH changes. At pH 2.2 the enzyme existed as metal-free apo-matrilysin and was not capable of binding an inhibitor. At pH 4.5-7.0 the enzyme associated specifically with zinc and calcium cations and became active in inhibitor binding. Although the stoichiometries of the metal cofactors varied (zero to two zinc and/or calcium ions) in the free enzyme dependent on solution pH, the predominant form of the enzyme-inhibitor complexes in the pH range of 4.5-7.0, in contrast, always had the metal association stoichiometry of 2Zn + 2Ca, which was the same stoichiometry the most active free metallo-enzyme had at the optimal pH of 7. At the activity onset pH of 4.5 matrilysin existed mostly as apo-enzyme (but in a conformation different from the denatured one at pH 2.2) and bound to an inhibitor slowly (time constant ∼ 2.5 min) to form the noncovalent metallo-enzyme-inhibitor complex. Of the two inhibitors studied, the one with the higher solution binding constant also produced larger ion signals for the noncovalent complex in the solvent-free gas phase, which pointed to the feasibility of the use of ESI-MS for inhibitor screening studies.

Remobilization partially restored the bone mass in a non-growing cancellous bone site following long term immobilization

There is no report in the rat of the effects of remobilization (RM) in an adult bone site. The aim of this study was to determine whether complete recovery from IM-induced bone loss will occur in a non-growing bone site, the distal tibia. Seventy-five 6-month-old virgin Sprague-Dawley female rats were used in this study. Their hindlimbs were immobilized against the abdomen with bandages for 18 weeks, then remobilized for 2, 10 or 20 weeks. Distal tibial sections were analyzed in the former epiphysis, 0.3 mm proximal from the calcified cartilage, and in trabecular bone of the former metaphysis between 0.3 mm and 1.92 mm proximal to the former epiphysis. A significant bone loss occurred in both former epiphyseal and metaphyseal trabeculae at 18 weeks after IM. The lost bone was partially recovered at 10 weeks of RM, but the bone mass was still lower than in aging controls by the end of the study. The partial recovery was characterized by decreasing former epiphyseal bone porosity and thickening of former metaphyseal trabeculae with no effect on trabecular number. We concluded that both distal tibia regions only partially recovered, during 20 weeks of RM from the long time IM.