Search PubMed⌕ Search

Biomedical subjects

A Black

Publications and source records attributed to A Black.

At least 55 records · Page 3Linked to original sources
PubMed1999

Diurnal variation and age differences in the biochemical markers of bone turnover in horses.

Biochemical markers of bone turnover provide sensitive, rapid, and noninvasive monitoring of bone resorption and formation. Serum concentrations of osteocalcin (OC) reflect rates of bone formation, and urinary concentrations of the pyridinium crosslinks pyridinoline (Pyd) and deoxypyridinoline (Dpd) are specific and sensitive markers of bone resorption. These markers are age-dependent and are used to detect and monitor changes in the rates of bone turnover in a variety of orthopedic diseases in humans and may prove to have similar application in horses. This study examined age differences and diurnal variation in OC, Pyd, and Dpd in eight adult geldings and seven weanling colts. Blood and urine were collected at regular intervals over 24 h. Serum OC and cortisol, and urinary Pyd and Dpd were analyzed. Mean 24-h concentrations of cortisol and all three markers were higher (P<.003) in weanlings than adults. Significant 24-h variation was observed in adult gelding OC, Pyd, and Dpd concentrations (P< .02). Adult OC concentrations were highest between 2400 and 0900; Pyd and Dpd peaked between 0200 and 0800. Similar patterns of bone turnover were observed in weanling values, but they were not significant (P>.17) owing to greater variability between individuals. Cortisol secretion varied (P<.001) over 24 h in both adults and weanlings and, thus, did not seem to be responsible for greater variability in markers of bone turnover between weanlings. These data demonstrate that diurnal rhythms exist for serum OC and urinary Pyd and Dpd in adult horses, as reported in humans, and that sample timing is an important consideration in future equine studies using these markers.

Aging↗
PubMed1999

Bone density and bone turnover in patients with osteoarthritis and osteoporosis.

OBJECTIVE: Osteoarthritis (OA) and osteoporosis (OP) are reported to be rare in the same patient. We examined bone mass, bone turnover, and radiological presence of OA in a group of patients with OA with previous hip fractures and age matched controls. METHODS: Bone mass was assessed by bone mineral density (BMD), using dual energy x-ray absorptiometry (DEXA) of the hip and total body, and quantitative ultrasound of the os calcis, measuring broadband ultrasound attenuation and velocity of sound. Bone turnover was assessed by measuring urinary pyridinium crosslinks and serum osteocalcin. RESULTS: There were differences in bone density, the patients with OP having lower bone density, while patients with OA had similar or increased bone density compared to controls, Serum osteocalcin showed no significant differences among the 3 groups of patients. Urinary pyridinium crosslinks excretion was significantly elevated in the OA group but not in the OP group compared with controls. CONCLUSION: Increased bone turnover was restricted to the OA group.

Absorptiometry, Photon↗
PubMed1998

Pre- and postnatal toxicity of the HMG-CoA reductase inhibitor atorvastatin in rats.

Atorvastatin is a potent inhibitor of the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, which catalyzes the conversion of HMG-CoA to mevalonate and constitutes the rate-limiting step in the biosynthesis of cholesterol. Steroid hormones derived from cholesterol, as well as mevalonate and its isoprenoid derivatives, provide important contributions to the maternal animal during pregnancy and lactation, as well as to the growth and development of the offspring; these contributions may potentially be influenced by inhibition of HMG-CoA reductase. To investigate the effects of atorvastatin on various aspects of reproduction and development, female Sprague-Dawley rats received 0, 20, 100, or 225 mg/kg daily by gavage from gestation day 7 through lactation day 20. Maternal toxicity, characterized by morbidity/mortality (13%), reduced body weight gain and food consumption, and pathologic lesions in the nonglandular mucosa of the stomach, occurred at 225 mg/kg. Offspring survival at birth and during the neonatal period at 225 mg/kg was reduced relative to control by up to 45%, and 28% of litters had no viable offspring by 10 days postpartum. Additional effects on offspring included reduced body weight during the neonatal and maturation periods (100, 225 mg/kg), delayed appearance of pinnae detachment and incisor eruption (225 mg/kg), impaired rotorod performance (females only; 100, 225 mg/kg), reduced acoustic startle responding (males only; 20, 100, 225 mg/kg), and transient effects on shuttle avoidance (females only; 225 mg/kg). No treatment-related effects were observed on offspring reproduction. In a separate experiment, a single dose of 10 mg/kg atorvastatin administered to female Wistar rats on gestation day 19 or lactation day 13 provided evidence of placental transfer and excretion into the milk. Results of this study indicate that pre- and postnatal administration of atorvastatin to female rats produces developmental toxicity in their offspring via in utero and/or lactational exposure, and in the presence or absence of maternal toxicity.

Animals↗
PubMed1998

Disposition kinetics of cobalt mesoporphyrin in mouse, rat, monkey and dog.

1. Radiometric and UV analyses indicated > 95% unchanged cobalt mesoporphyrin (CoMP) in plasma after i.v. or i.m. administration. Blood clearance of CoMP is < 2% of hepatic blood flow in mouse and rat, and < 0.5% of hepatic blood flow in monkey and dog. CoMP elimination t1/2 ranged from 3.1 to 9.9 days in animals after i.v. administration. 2. CoMP is highly (> 99.5%) bound to plasma proteins, but has low affinity for blood cells (Kp < 0.15). The volume of CoMP distribution (Vss < 0.91/kg) is reflective of a distribution to total body water following i.v. administration to mouse, rat, monkey and dog. 3. [14C]CoMP reached highest levels in rat tissue between 1 and 4 days following i.m. injection. Liver, kidney cortex, lymph node, adrenal and spleen demonstrated greatest uptake of radiolabel. Concentration in tissues was readily detectable at 60 days post-dose. 4. CoMP was slowly absorbed after i.m. administration showing dose-dependent pharmacokinetics. The major route of radiolabel elimination was faecal excretion (54% of dose) in rat after an i.m. dose of [14C]CoMP. Approximately 1% of the 14C dose was recovered in the urine over 7 days post-dose. 5. As a polar metalloporphyrin, CoMP has low clearance, restricted tissue distribution and long elimination t1/2 in the laboratory animals.

Animals↗
PubMed1998

Tissue engineered neocartilage using plasma derived polymer substrates and chondrocytes.

This study demonstrates that fibrin monomers can be polymerized into moldable gels and used for the encapsulation of isolated chondrocytes. This biologically derived scaffold will maintain three-dimensional spatial support, allowing new tissue development in a subcutaneous space. Chondrocytes isolated from the glenohumeral and humeroradioulnar joints of a calf were combined with cyroprecipitate and polymerized with bovine thrombin to create a fibrin glue gel with a final cell density of 12.5 x 10(6) cells/ml. The polymer-chondrocyte constructs were implanted subcutaneously in 12 nude mice and incubated for 6 and 12 weeks in vivo. Histologic and biochemical analysis including deoxyribonucleic acid (DNA) and glycosaminoglycan quantitation confirmed the presence of actively proliferating chondrocytes with production of a well-formed cartilaginous matrix in the transplanted samples. Control specimens from 12 implantation sites consisting of chondrocytes alone or fibrin glue substrates did not demonstrate any gross or histologic evidence of neocartilage formation. Moldable autogenous fibrin glue polymer systems have a potential to serve as alternatives to current proprietary polymer systems used for tissue engineering cartilage as well as autogenous grafts and alloplastic materials used for facial skeletal and soft-tissue augmentation.

Animals↗
PubMed1998

Development, validation, and interlaboratory comparison of an HMG-CoA reductase inhibition assay for quantitation of atorvastatin in plasma matrices.

An HMG-CoA reductase inhibition assay was developed and validated for quantitation of atorvastatin in human, dog, rat, and mouse plasma. Atorvastatin was isolated from plasma by protein precipitation. Rat-liver microsomes were used to provide the reductase enzyme. The method was validated by assaying calibration standards and quality controls in triplicate on each of the 3 days. A customized computer program was used for data calculation. Quantitation of the assay ranged from 0.36 to 16 ng/ml of atorvastatin in different plasma matrices. Assay precision and accuracy, based on the coefficient of variation and percent relative error, respectively, of quality controls were 10.4% to 14.5% and within +/- 6.25% in human; 4.89% to 10.6% (+/- 8.13%) in dog; 2.68% to 8.62% (+/- 5.00%) in rat; and 3.68% to 8.96% (+/- 5.38%) in mouse plasma. The method has been applied to pharmacokinetic studies of atorvastatin in human and toxicokinetic studies in dog, rat, and mouse after atorvastatin administration. Atorvastatin equivalent concentrations in a set of plasma samples from subjects receiving single and multiple doses of atorvastatin were determined by validated HMG-CoA reductase inhibition assays at four different laboratories. Results were compared using linear regression and concordance correlation statistical procedures. Good agreements among these data indicated that results from different laboratories with the same validated method can be used interchangeably.

Animals↗
PubMed1998

Gammadelta+ T cells preferentially respond to live rather than killed malaria parasites.

We have compared the in vitro responses of peripheral blood T cells from malaria-unexposed donors to live Plasmodium falciparum schizonts, freeze-thawed schizont extracts (P. falciparum schizont extracts [PfSE]), and parasite culture supernatants. We show that the cells responding to PfSE and parasite culture supernatants are predominantly CD4+ TCR alphabeta+ while in the presence of live schizonts there is an additional activation of TCR gammadelta+ cells. Activation of TCR gammadelta+ cells in response to PfSE was seen only when irradiated autologous feeder cells or recombinant interleukin-2 (IL-2) was added to the cultures. Live schizonts but not PfSE induced significant IL-2 production in vitro in the first 5 days after stimulation, suggesting that induction of early IL-2 by live parasites may contribute to the marked activation of the TCR gammadelta+ population.

Animals↗
PubMed1998

Tumor regression in mice following vaccination with human papillomavirus E7 recombinant protein in PROVAX.

Induction of CD8+ cytotoxic T lymphocytes (CTLs) specific for human papillomavirus (HPV) antigens provides an attractive strategy for immunotherapy of HPV-related cancers in humans. In this study, we investigated the potential of utilizing soluble E7 protein of HPV 16 in an adjuvant formulation, PROVAX as a vaccine against a progressively growing E7 transfected K1735-X21 (H-2k) metastatic melanoma cells (HOPE2) in a mouse model. Vaccination of HOPE2 tumor bearing mice (C3H) with E7 protein in PROVAX resulted in significant inhibition of tumor growth, compared to mice vaccinated with E7 in Alum or saline. In vivo depletion of CD8+ or CD4+ cells indicated that CD8+ cells are the major effector cells in mediating the anti-tumor activity in this model. Furthermore, E7-specific CTL activity in vitro was detected in tumor bearing mice vaccinated with E7-PROVAX. Our studies suggest that recombinant HPV antigens in combination with PROVAX could serve as an effective subunit vaccine to stimulate tumor specific CD8+ T cell mediated immunity against HPV-related cancers.

Adjuvants, Immunologic↗
PubMed1998

Measures of urine concentration in maternal urine screening for Down syndrome.

A study was carried out to assess eight methods of normalizing the level of urinary beta-core human chorionic gonadotropin (hCG) for variable urine concentration. We compared the standard approach--creatinine determination by the Jaffe method--with high performance liquid chromatography (HPLC) measurement of creatinine, osmolarity and optical density at five wavelengths. Urine samples were included from a total of 472 women with unaffected singleton pregnancies at 15 weeks' gestation. The median beta-core hCG value was determined for each decile group when the results were ranked in turn according to the different measures of urine concentration. Creatinine using the Jaffe method had a much stronger relationship with median beta-core hCG than the other measures. Linear regression across the decile groups gave an R2 value for Jaffe of 0.85 compared with HPLC of 0.53, osmolarity of 0.52, optical density at 405 nm of 0.72, at 450 nm of 0.57, at 490 nm of 0.33, at 570 nm of 0.34 and at 630 nm of 0.33. We conclude that when screening with urinary beta-core hCG measuring creatinine appears to be an adequate method of allowing for variable urine concentration.

Chorionic Gonadotropin, beta Subunit, Human↗
PubMed1997

Public health. Capital gains.

Private investors should be encouraged to support initiatives other than hospitals. Primary care in inner cities should be strengthened and reorganised. The potential of the ambulance service needs to be harnessed.

Capital Financing↗
PubMed1997

Fluoxetine in depressed alcoholics. A double-blind, placebo-controlled trial.

BACKGROUND: The selective serotonergic medication fluoxetine has demonstrated efficacy in the treatment of major depression and has suggested efficacy in the treatment of alcoholism. However, no completed trials with any selective serotonergic medication have been reported in patients who display both major depression and alcoholism, despite previous observations that both depression and alcoholism are associated with low serotonergic functioning. METHODS: Fifty-one patients diagnosed as having comorbid major depressive disorder and alcohol dependence were randomized to receive fluoxetine (n = 25) or placebo (n = 26) in a 12-week, double-blind, parallel-group trial. Weekly ratings of depression and alcohol consumption were obtained throughout the 12-week course of the study. RESULTS: The improvement in depressive symptoms during the medication trial was significantly greater in the fluoxetine group than in the placebo group. Total alcohol consumption during the trial was significantly lower in the fluoxetine group than in the placebo group. CONCLUSIONS: Fluoxetine is effective in reducing the depressive symptoms and the alcohol consumption of patients with comorbid major depressive disorder and alcohol dependence. It is unknown whether these results generalize to the treatment of less depressed and less suicidal alcoholics.

Adult↗
PubMed1997

A comparison of midazolam with trimeprazine as an oral premedicant for children.

The effect of oral premedication was investigated in a double-blind, randomised trial in 85 children undergoing tonsillectomy and/or adenoidectomy. Orally administered midazolam 0.5 mg.kg-1 given 30 min pre-operatively was compared with trimeprazine 2 mg.kg-1 given 90 min pre-operatively and a placebo preparation. Compliance, sedation and ease of induction were assessed as were the duration and quality of recovery. Following premedication with midazolam none of the patients was anxious, crying or distressed on leaving the ward, compared with 2/28 in the trimeprazine group and 5/28 in the placebo group (p = 0.0007). More patients were calm and quiet on arrival in the anaesthetic room following midazolam than following trimeprazine, with both premedicant agents comparing favourably with placebo. There was no significant difference between the three groups in the time to recovery or the sedation score on discharge to the ward. Midazolam is a safe and effective oral premedicant for children.

Adenoidectomy↗
PubMed1997

Double-blind fluoxetine in depressed alcoholic smokers.

Treatment trials involving smoking in alcoholics with major depression are scarce, despite the common co-occurrence of these disorders. In this study, 25 smokers with DSM-III-R diagnoses of both major depressive disorder and alcohol dependence were randomized to fluoxetine or placebo in a 12-week, double-blind, parallel group trial. Almost half (48%) of the patients had made a suicide attempt in the week before hospitalization (where recruitment was performed), and 84 percent reported suicidal ideations during that week. Those in the fluoxetine group demonstrated a significant within-group decrease in smoking during the course of the study, whereas those in the placebo group did not. Those in the fluoxetine group smoked 27 percent fewer cigarettes than those in the placebo group, although this difference was not statistically significant. Cumulative alcohol consumption during the 12 weeks of the pharmacotherapy trial was four times as high in the placebo group as in the fluoxetine group, though this difference was not statistically significant in this limited-sized sample. The change in smoking was significantly associated with a change in drinking. These preliminary findings suggest that fluoxetine has the potential for treating the smoking and drinking behaviors of depressed alcoholic smokers.

Adult↗
PubMed1996

Comparison of caudal bupivacaine and diamorphine with caudal bupivacaine alone for repair of hypospadias.

Forty-five boys undergoing repair of hypospadias were allocated randomly to one of two groups. After induction of anaesthesia, 22 patients received 0.25% caudal bupivacaine 0.5 ml kg-1 and diamorphine 30 micrograms kg-1 and the remaining 23 patients received 0.25% caudal bupivacaine 0.5 ml kg-1 alone. Pain scores (Children's Hospital of Eastern Ontario Pain Scale), sedation scores, ventilatory frequency, analgesic requirements and associated side effects were recorded for the first 24 h after operation. The two groups were indistinguishable in age, weight and duration of surgery. There was a statistically significant reduction in early pain scores. There was also a statistically significant increase in the time to first passage of urine in those boys in the diamorphine group who were not catheterized during operation.

Analgesics, Opioid↗
PubMed1996

Acquired cutis laxa associated with a plasma cell dyscrasia.

Acquired cutis laxa (generalized acquired elastolysis) is characterized by skin laxity often with systemic involvement of the lungs, aorta, gastrointestinal tract, and pelvic organs. Although there have been many speculations regarding its pathogenesis, the etiology of this condition is still unclear. We describe a patient with generalized acquired cutis laxa associated with a plasma cell dyscrasia. Immunofluorescence studies were used to evaluate the pathogenesis of the elastolysis. Lesional skin was examined by direct and indirect immunofluorescence techniques for evidence of deposition of immunoglobulins on elastic fibers in the dermis. Direct immunofluorescence revealed deposition of IgG on elastic fibers in the dermis. Some patients with acquired cutis laxa have underlying lymphoreticular disorders such as plasma cell dyscrasia and may have immunoglobulins deposited on dermal elastic fibers. Immune-mediated mechanisms may play a major role in the pathogenesis of acquired cutis laxa in at least some cases.

Adult↗
PubMed1996

A comparison of the induction characteristics of sevoflurane and halothane in children.

The induction characteristics of sevoflurane and halothane were compared in 81 children aged 6 months to 6 years. The mean time taken to achieve loss of eyelash reflex was significantly shorter with sevoflurane than with halothane (sevoflurane, mean time (SD) 1 min 41 s (35 s), halothane, mean time (SD) 2 min 17 s (43 s), t = 4.11, p = < 0.01). The mean time taken to complete induction (to achieve steady spontaneous ventilation and small pupils with central gaze) was also shorter in children induced with sevoflurane (sevoflurane, mean time (SD) 3 min 58 s (1 min 8 s), halothane, mean time (SD) 4 min 50 s, (1 min 27 s), t = 2.29, p = 0.027). Effects on heart rate, blood pressure and oxygen saturation during induction were similar for both agents. There were no major complications during induction with either halothane or sevoflurane.

Anesthesia, Inhalation↗
PubMed1996

A comparison of the recovery characteristics of sevoflurane and halothane in children.

The recovery characteristics of sevoflurane and halothane anaesthesia were compared in 40 children aged 6 months to 6 years undergoing day case surgery. The mean time taken to open eyes after surgery had ended was appreciably and significantly shorter after sevoflurane than after halothane (sevoflurane, mean time (SD) 7 min 52 s (5 min 46 s), halothane, mean time (SD) 15 min 50 s (9 min 2 s), t = 3.32, p = 0.002). The time taken to be ready for discharge from the recovery unit to the ward was also significantly shorter after sevoflurane than after halothane (sevoflurane, mean time (SD) 12 min 46 s (4 min 11 s), halothane, mean time (SD) 19 min 13 s (9 min 48 s), t = 2.7, p < 0.01). However, more children were in pain and given analgesia after sevoflurane (p < 0.01) and the mean time to reach the criteria for discharge home was similar in both groups (sevoflurane, mean time (SD) 2 h 9 min (17 min), halothane, mean time (SD) 2 h 4 min (8 min)). There were no major complications in either group.

Ambulatory Surgical Procedures↗