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Biomedical subjects

T Hughes

Publications and source records attributed to T Hughes.

At least 55 records · Page 3Linked to original sources
PubMed1998

17beta-estradiol regulation of protein kinase C activity in chondrocytes is sex-dependent and involves nongenomic mechanisms.

17Beta-estradiol (E2) regulates growth plate chondrocyte differentiation in both a sex- and cell maturation-dependent manner, and the sex-specific effects of E2 appear to be mediated in part by membrane events. In this study, we examined whether E2 regulates protein kinase C (PKC) in a cell-maturation and sex-specific manner and whether E2 uses a nongenomic mechanism in regulating this enzyme. In addition, we determined if PKC mediates the E2-dependent stimulation of alkaline phosphatase activity seen in chondrocytes. Confluent, fourth passage resting zone (RC) and growth zone (GC) chondrocytes from male and female rat costochondral cartilage were treated with 10(-10) to 10(-7) M E2. E2 caused a dose-dependent increase in PKC in RC and GC cells from female rats. Peak stimulation was at 90 min. Increased PKC was evident by 3 min in both RC and GC and was still evident in RC cells at 720 min, but in GC cells activity returned to baseline by 270 min. Actinomycin D had no effect at 9, 90, 270, or 720 min, but there was a small decrease in E2-stimulated PKC in RC treated with cycloheximide at 90 and 270 min and in GC treated for 90 min. E2 increased cytosolic and membrane PKC at 9 min and by 90 min promoted translocation of PKC activity from the cytosol to the membranous compartment of female RC cells. Antibodies specific for the alpha, beta, delta, epsilon, and zeta isoforms of PKC revealed that PKCalpha in female GC and RC cells is activated by E2. There was a small, but statistically significant, increase in PKC in male RC cells in response to E2, but it was not dose-dependent, and no effect of E2 was noted in male GC cells. 17Alpha-estradiol, an inactive isomer of E2, did not affect PKC specific activity in RC or GC cells from either female or male rats. Chelerythrine, a specific inhibitor of PKC, inhibited E2-dependent alkaline phosphatase activity, indicating that E2 mediates its rapid effects on alkaline phosphatase via PKC.

Alkaline Phosphatase↗
PubMed1998

Making genes green: creating green fluorescent protein (GFP) fusions with blunt-end PCR products.

The jellyfish green fluorescent protein (GFP) has proven to be a useful tool in protein localization and trafficking studies. Fused to GFP, a protein of interest can be visualized and tracked in vivo through fluorescence microscopy. However, the process of making these fusion proteins is often tedious and painstaking. Here, we describe a simple and quick method for creating GFP fusion proteins using blunt-end PCR product ligation.

Base Sequence↗
PubMed1997

Developmental and sensory-dependent changes of phosphoinositide-linked metabotropic glutamate receptors.

Metabotropic glutamate receptors (mGluRs) can modulate synaptic transmission, and there is evidence that phosphoinositide (PI)-linked mGluRs may be involved in sensory-dependent plasticity during the development of cat visual cortex. Consequently, we asked the questions: Where are the PI-linked mGluRs (mGluR1alpha and mGluR5) in the visual cortex? Does the quantity and distribution of these receptors change in the cat visual cortex during postnatal development, and are these features sensory-dependent? We found that the quantity of mGluR1alpha decreases with age, whereas the laminar distribution of mGluR1alpha remains the same. Quantity of mGluR5 also decreases, but the laminar distribution of mGluR5 changes during development. The pattern and timing of the mGluR5 change in distribution follow the development of geniculocortical afferents. Immunostaining indicates that reduction of receptor occurs mainly in layers V-VI for mGluR1alpha and outside layer IV for mGluR5. Dark-rearing postpones the laminar change of mGluR5 and produces an increased level of mGluR5 between postnatal 1.5-6 weeks of age but has no significant effect on the mGluR1alpha distribution or the mGluR1alpha quantity. These results suggest that mGluR1alpha and mGluR5 are involved in different aspects of cortical development. The mGluR5 is more likely to be involved in sensory-dependent events than mGluR1alpha. The lack of developmental correlation between mGluR quantities and the critical period for ocular dominance plasticity also suggests that other factors besides mGluR quantities are important for ocular dominance plasticity.

Aging↗
PubMed1997

Anatomy of the arterial supply to the liver demonstrated by MRI.

The aim of this study was to establish the accuracy of dynamic contrast-enhanced magnetic resonance imaging (DCEMRI) in assessing the site of origin and the patency of the hepatic arteries. Sixty-one patients were examined with serial DCEMRI. MRI was performed at 1.0 T with a rapid multi-section breath-hold fast low-angle shot (FLASH) technique in the coronal oblique plane before and at 10, 40 and 70 s after a bolus of gadolinium-DTPA. The hepatic, left gastric, gastroduodenal, splenic and superior mesenteric arteries were examined. The main portal vein, its right and left intrahepatic divisions, and the splenic and superior mesenteric veins were also assessed. The common hepatic artery was occluded in one patient. The right hepatic artery was seen in 59 patients, left hepatic in 54, left gastric in 43, gastroduodenal in 54, splenic in 60 and superior mesenteric artery in 61. Results were concordant with surgery in 38 of 39 cases and with X-ray angiography in 21 of 22 cases. In the detection of aberrant vessels DCEMRI had a sensitivity of 89 %, a specificity of 100 % and an accuracy of 97 %. All five veins were occluded in 1 patient. The main portal vein was patent in 56 patients, occluded in 2 and narrowed in 2. Thirty-two patients had upper abdominal varices. It is concluded that DCEMRI with sequential imaging provides a non-invasive demonstration of hepatic arterial and venous structures.

Adult↗
PubMed1997

Hypotension during hemodialysis: role for nitric oxide.

Hypotensive episodes during hemodialysis are a frequent complication in patients with end-stage renal disease. The possibility that nitric oxide (NO), a major regulator of cardiovascular hemodynamics, could be a factor was explored. Pre and postdialysis plasma samples from 17 hemodialysis patients were analyzed for the stable end products of NO,nitrite + nitrate (NO2 + NO3), by the Greiss method. Predialysis NO2 + NO3 levels were significantly higher in end-stage renal disease than in nine age-matched controls (44.08 +/- standard error of mean 5.74 versus 18.67 +/- 3.56 uM, P = 0.017). In more than half of the patients, postdialysis values dropped markedly, whereas in others the value change was far less; several rose above predialysis values. Depending on the nitrite + nitrate reduction ratio (pre minus postdialysis NO2 + NO3 divided by the predialysis value) patients were separated into two groups, A (n = 9 where nitrate + nitrate reduction ratio was > 0.5 and B (n = 8 where nitrate + nitrate reduction ratio was < 0.5). Whereas the mean predialysis NO2 + NO3 values between groups A and B did not differ significantly, postdialysis levels fell from a predialysis mean of 50 uM to 12 uM in group A but rose from 37 uM to 45 uM in group B. The difference between the postdialysis values of group A and group B was significant (P = 0.0264). In group B, mean systolic blood pressure dropped more than in group A, (57.8 mm Hg compared with 21.2 mm Hg, P = 0.0078). When measured by analysis of variance for repeated measures, skin and core temperatures and blood pressures were lower in group B than in group A. The volume of the ultrafiltrate was removed and dialysis duration and mean weight loss did not differ. Thus, in group B, apparently NO formation increased during hemodialysis exceeding the rate of removal or metabolism of the end products, whereas in group A, NO2 + NO3 removal or metabolism was without apparent increase in the formation of NO. The basis for this difference is unknown. Because vasodilation is a major effect of NO, the strong association of severe reduction in blood pressures and increased NO synthesis in subset B suggests a role for NO in hypotensive episodes during hemodialysis.

Adult↗
PubMed1996

Computerized planimetry in the objective assessment of the antispasmodic effect of Zamifenacin in double contrast barium enemas.

A prospective, randomized, double-blind study was undertaken to evaluate Zamifenacin 30 mg (Pfizer Ltd), a novel, orally-administered, gut-specific muscarinic receptor antagonist, as an adjuvant to the double contrast barium enema examination (DCBE). Zamifenacin was compared with placebo in terms of side-effects and colonic tone. Analysis of colonic tone was carried out by two independent observers, using a subjective grading system and also by an objective method using computerized planimetry. Interobserver variability was also assessed. Zamifenacin is safe and well tolerated but at the prescribed dose is an ineffective antispasmodic for DCBE. Subjective assessment of colonic tone was shown to be of limited value whilst the objective analysis using computerized planimetry was reliable and highly reproducible.

Adolescent↗
PubMed1995

Immunohistochemical study of two phosphoinositide-linked metabotropic glutamate receptors (mGluR1 alpha and mGluR5) in the cat visual cortex before, during, and after the peak of the critical period for eye-specific connections.

The distribution of two phosphoinositide-linked metabotropic glutamate receptors (mGluR1 alpha and mGluR5) was studied immunohistochemically in area 17 before, during and after the peak of use-dependent modification of eye-specific connections. In the adult, mGluR1 alpha immunoreactivity is high in all layers except layer IV, where mGluR5 immunoreactivity is concentrated. This difference in distribution indicates different functions for these two receptor subtypes. The laminar pattern of mGluR1 alpha immunoreactivity is similar in all three ages, but the overall labeling intensity decreases after the peak (6 weeks of age) of the critical period. The laminar pattern of mGluR5 immunoreactivity changes with age. It is expressed in most layers at 2 days of age and is found mainly in layer IV in the adult. This laminar distribution and developmental pattern match the distribution and the development of the geniculocortical terminals. The change in mGluR1 alpha labeling intensity and mGluR5 laminar distribution over time is consistent with both of these mGluRs being involved in sensory-dependent plasticity for eye-specific connections in the visual cortex.

Animals↗
PubMed1995

Barnett continent intestinal reservoir. Multicenter experience with an alternative to the Brooke ileostomy.

PURPOSE: Since 1988, surgeons at five hospitals have been performing the Barnett continent intestinal reservoir (BCIR). The BCIR includes modifications to the original Kock pouch, designed to reduce the incidence of valve slippage and fistula formation. Principle modifications include an intestinal collar, an isoperistaltic valve, and a lateral pouch design. METHOD: This unique collaborative study includes 510 ulcerative colitis or familial polyposis patients, with a follow-up time from one to five years postoperatively. RESULTS: Ninety-two percent still have functioning reservoirs. Six and one-half percent have had their pouches removed and replaced with conventional Brooke ileostomies. Reoperation rate for major pouch-related complications (other than pouch removal) was 12.8 percent. These complications included slipped valve (6.3 percent), valve fistulas (4.5 percent), and pouch fistulas (6.3 percent). Several questions were administered to patients whose responses revealed a significant improvement in general quality of life, state of mind, and overall health. CONCLUSIONS: The BCIR represents a successful alternative to patients with a conventional Brooke ileostomy or those who are not candidates for the ileal pouch-anal anastomosis.

Adenomatous Polyposis Coli↗
PubMed1995

Aphasia secondary to partial status epilepticus of the basal temporal language area.

We present a patient with aphasia of several days' duration that was secondary to spontaneous partial status epilepticus arising from the left basal temporal region. Evidence from MRI, EEG, and PET confirmed the origin of the seizures in the basal temporal area. Both the seizure discharges and the aphasia resolved after antiepileptic therapy. This case, to our knowledge, is the first documented example of epileptic aphasia secondary to spontaneous partial status epilepticus originating from the basal temporal area.

Aphasia↗