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Biomedical subjects

R W Hardy

Publications and source records attributed to R W Hardy.

At least 19 recordsLinked to original sources
PubMed1992

Genetic dissection of cyclophilin function. Saturation mutagenesis of the Drosophila cyclophilin homolog ninaA.

Cyclophilins, the intracellular receptors for the widely used immunosuppressant cyclosporin A have been found to be peptidyl-prolyl cis/trans isomerases and have been implicated in intracellular protein folding and trafficking. The Drosophila ninaA gene encodes a photoreceptor-specific cyclophilin homolog involved in rhodopsin biogenesis. ninaA mutants have a 90% reduction in the levels of Rh1 rhodopsin. To gain insight into the role of cyclophilins in vivo, we carried out a genetic screen designed to identify functionally important regions in the ninaA protein. Over 700,000 mutagenized flies were screened for a visible ninaA phenotype and 70 independent mutations in ninaA were isolated and characterized. These mutations provide a detailed dissection of the structure/function relationships in cyclophilin. We also show that mammalian cyclophilins engineered to contain missense mutations found in two temperature-sensitive ninaA alleles display temperature-sensitive prolyl cis/trans isomerase activity.

Alleles↗
PubMed1992

The effects of extracellular calcium and epinephrine on cytosolic-free calcium in single rat adipocytes.

Changes in cytosolic calcium concentration ([Ca2+]i) in response to extracellular calcium and epinephrine were monitored in individual rat adipocytes by both photon counting and digital imaging techniques utilizing the intracellular fluorescent calcium probes Fura-2 and Indo-1. Adipocytes containing Fura-2 were attached to coverslips and shown to be as hormonally responsive to insulin as adipocytes in suspension [3.5 +/- 0.8 (n = 5) vs. 4.2 +/- 0.6 (n = 8)-fold increase in glucose oxidation over basal in response to 0.7 nM insulin]. Basal [Ca2+]i in single rat adipocytes was found to be 128 +/- 6 nM (n = 100). The addition of either extracellular calcium or epinephrine elicited transient, concentration-dependent increases in [Ca2+]i. Although the characteristics of calcium- and epinephrine-induced calcium transients are generally similar, the peak [Ca2+]i increase over basal is higher in response to calcium vs. epinephrine [37 and 64% (1 and 27 microM epinephrine), vs. 132 and 236% (2 and 4 mM calcium)]. All the cells tested responded to calcium but only 67% responded to epinephrine. Both alpha- and beta-adrenergic agonists were able to increase [Ca2+]i. The epinephrine-induced [Ca2+]i transients appear to be dependent upon extra-cellular calcium. Neither cholera nor pertussis toxin treatments altered basal [Ca2+]i. However, after treatment of adipocytes with either pertussis or cholera toxin, epinephrine stimulated oscillations in [Ca2+]i. Digital imaging revealed that adipocytes demonstrate a high degree of intracellular spatial heterogeneity and intercellular variability in the magnitude of response to both calcium and epinephrine. These studies demonstrate the feasibility of using single rat adipocytes to monitor intracellular free calcium, using both photon counting and digital imaging.

Adipose Tissue↗
PubMed1992

A multicenter evaluation of lipid profiling with a compact analyzer (Miles Clinistat).

We evaluated the Clinistat Analyzer (Miles Inc., Diagnostics Division, Elkhart, IN) for measuring cholesterol, triglycerides, and high-density lipoprotein (HDL) cholesterol at three medical centers. The system, based on multilayer film technology, uses precalibrated, dry film reagent disks. Ten microliters of serum is applied to the dry film reagent disk in the test procedure. For HDL-cholesterol measurement, serum is pretreated by precipitation with phosphotungstic acid and magnesium chloride. Total precision (CVs) of each of the three assays was less than or equal to 5%. The assay ranges were linear and satisfactory for clinical use. Patients' results compared well with established methods. No significant interferences were found with hemolysis, icterus, and lipemia.

Chemistry, Clinical↗
PubMed1991

Photoreceptor deactivation and retinal degeneration mediated by a photoreceptor-specific protein kinase C.

The protein kinase C (PKC) family of serine-threonine kinases has been implicated in the regulation of a variety of signaling cascades. One member of this family, eye-PKC, is expressed exclusively in the Drosophila visual system. The inaC (inactivation-no-afterpotential C) locus was shown to be the structural gene for eye-PKC. Analysis of the light response from inaC mutants showed that this kinase is required for the deactivation and rapid desensitization of the visual cascade. Light adaptation was also defective in inaC mutant flies. In flies carrying the retinal degeneration mutation rdgB, absence of eye-PKC suppressed photoreceptor cell degeneration. These results indicate that eye-PKC functions in the light-dependent regulation of the phototransduction cascade in Drosophila.

Adaptation, Physiological↗
PubMed1991

Palmitate stimulates glucose transport in rat adipocytes by a mechanism involving translocation of the insulin sensitive glucose transporter (GLUT4).

In rat adipocytes, palmitate: a) increases basal 2-deoxyglucose transport 129 +/- 27% (p less than 0.02), b) decreases the insulin sensitive glucose transporter (GLUT4) in low density microsomes and increases GLUT4 in plasma membranes and c) increases the activity of the insulin receptor tyrosine kinase. Palmitate-stimulated glucose transport is not additive with the effect of insulin and is not inhibited by the protein kinase C inhibitors staurosporine and sphingosine. In rat muscle, palmitate: a) does not affect basal glucose transport in either the soleus or epitrochlearis and b) inhibits insulin-stimulated glucose transport by 28% (p less than 0.005) in soleus but not in epitrochlearis muscle. These studies demonstrate a potentially important differential role for fatty acids in the regulation of glucose transport in different insulin target tissues.

3-O-Methylglucose↗
PubMed1991

Cervical paraganglioma with subsequent intracranial and intraspinal metastases. Case report.

Paragangliomas, tumors derived from the extra-adrenal paraganglion system, have commonly been found in the retroperitoneum, abdomen, mediastinum, skull base, and neck. Rare intraspinal cases have included involvement of the cauda equina and filum terminale, and a recent case has been reported of thoracic cord paraganglioma with metastasis to the cauda equina. The authors present the case of a patient with a cervical paraganglioma who underwent subtotal resection followed by postoperative irradiation; she subsequently developed multiple intracranial and intraspinal metastases 7 months following the first decompression procedure.

Adult↗
PubMed1990

Uses of biotechnology and technology transfer to keep food safe.

The era of biology is composed of 1) the definition of molecular laws of biology, 2) the exponential expansion of the data base, and 3) the establishment of the first generation molecular and cellular tool kit; this era is driving the development and commercialization of biotechnological products and processes for agriculture and the food system. These products and processes should have a major impact in maintaining and improving food safety. Several meeting and organizational initiatives on biotechnology and food safety are summarized. Possible roles of biotechnology in areas of food safety involve microbial contaminants, nutritional quality, natural antimetabolites, allergens, toxicants, and synthetic chemical residues. Biotechnology will have an impact on all these areas through both improved ability to measure as well as to modify microbes, animals, and plants used as food. Diagnostics for microbial contaminants and biobased alternatives to synthetic chemicals are most advanced. However, all these biotechnological products and processes for food safety are in very early stages of development and commercialization.

Animals↗
PubMed1988

Rapid development of enhanced clearance after high-dose cyclophosphamide.

We have studied the disposition of cyclophosphamide, its major cytotoxic metabolite phosphoramide mustard, and the synthetic glucocorticoid dexamethasone in nine patients receiving high-dose cyclophosphamide daily for 2 days before bone marrow transplantation. The total body clearance of cyclophosphamide was observed to increase from 93 +/- 27 ml/min on the first day to 178 +/- 83 ml/min on the second day. This was associated with an increase in the clearance of dexamethasone from 369 +/- 104 ml/min to 526 +/- 123 ml/min. An increased rate of formation of phosphoramide mustard with higher peak concentrations was also seen. Simulation studies show that these changes are most likely the result of an increase in the hepatic metabolism of cyclophosphamide. These results show that high-dose cyclophosphamide causes an increase in its own clearance and that of dexamethasone through an apparent induction of hepatic-metabolizing enzymes detectable 24 hours after initial exposure to cyclophosphamide.

Adult↗
PubMed1988

Solitary primary lymphoma of the sciatic nerve: case report.

An unusual case of a solitary extranodal primary lymphoma of the sciatic nerve in a patient presenting with sciatica and a left footdrop is described. Magnetic resonance imaging was successful in identifying a fusiform lesion in the sciatic nerve in the left infragluteal region. Surgical exploration and biopsy confirmed this as a B cell lymphoma. An extensive metastatic work-up has not identified other sites of lymphomatous involvement.

Humans↗
PubMed1988

Disposition of cyclophosphamide on two consecutive cycles of treatment in patients with ovarian carcinoma.

The disposition of cyclophosphamide was determined in 12 women with ovarian carcinoma receiving cyclophosphamide 500 mg/m2, doxorubicin (adriamycin) 50 mg/m2 and cisplatin 50 mg/m2 during their first and second courses of therapy. Plasma samples were obtained over 24 h following the completion of the cyclophosphamide infusion and assayed for cyclophosphamide by high performance liquid chromatography. The mean disposition of cyclophosphamide conformed to a 2-compartment model with a mean terminal half-life of 7.14 h on the first course and 8.77 h on the second course. Mean area under the plasma concentration versus time curve appeared to increase from 248.8 mg.h/l for the initial course to 282.2 mg.h/l on the second. Mean total body clearance was 2.01 l/h/m2 on the first course and 1.77 l/h/m2 on the second. Volume of distribution on the first and second courses were 15.3 l/m2 and 18.1 l/m2, respectively. These results suggested that cyclophosphamide clearance decreased when given in a bolus fashion every 3 weeks. However, inter-patient and intra-patient variability was large and the differences in the calculated parameters were not statistically significant when the individual patient data was considered. It is concluded that: 1. cyclophosphamide disposition can best be fit by a bi-exponential equation; 2. considerable intra- and interpatient variability in the concentration-time profile will be encountered; 3. cyclophosphamide disposition does not change from the first to the second course. Reasons for the wide variation are proposed.

Adult↗
PubMed1987

Comparison of transketolase activity and thiamin pyrophosphate levels in erythrocytes and liver of rainbow trout (Salmo gairdneri) as indicators of thiamin status.

Yearling rainbow trout (Salmo gairdneri) were fed a purified diet with and without thiamin supplementation for 30 wk, at which time overt signs of thiamin deficiency appeared in the deficient group. Overt signs of thiamin deficiency were anorexia, darkening and ataxia. Death rapidly followed the development of overt thiamin deficiency. Transketolase activity and thiamin pyrophosphate levels were measured monthly in erythrocyte and liver samples. Significant differences in erythrocyte transketolase activity between fish fed the thiamin-deficient and control diets were measured after 24 wk of feeding. No significant difference in liver transketolase activity was found between trout fed diets with or without thiamin supplementation. Thiamin pyrophosphate levels were significantly lower in erythrocytes and liver of fish fed the thiamin-deficient diet after 16 wk of feeding. Thiamin pyrophosphate levels in erythrocytes and liver were found to be a more sensitive indicator of thiamin status of rainbow trout than erythrocyte or liver transketolase activity.

Animals↗
PubMed1987

Analysis of phosphoramide mustard by reversed-phase ion pair high pressure liquid chromatography.

The analysis of phosphoramide mustard by reversed-phase ion pair high pressure liquid chromatography using ultraviolet detection is described. The method will enable measurement of serum concentrations of phosphoramide mustard over a period of approximately 24 h after an i.v. dose of 60 mg/kg of cyclophosphamide and requires 0.5 ml of serum or plasma. The between-day precision of the assay at concentrations of 0.34, 2.76, and 6.90 mg/L gave coefficients of variation of 16, 10, and 9%, respectively. The percentage analytical recovery of phosphoramide mustard is 35%. Preliminary results providing pharmacokinetic data on two adults undergoing high-dose cyclophosphamide treatment prior to bone marrow transplant are presented.

Chromatography, High Pressure Liquid↗
PubMed1987

Acoustic (loudspeaker) facial EMG monitoring: II. Use of evoked EMG activity during acoustic neuroma resection.

Facial electromyographic (EMG) activity was continuously monitored via loudspeaker during eleven translabyrinthine and nine suboccipital consecutive unselected acoustic neuroma resections. Ipsilateral facial EMG activity was synchronously recorded on the audio channels of operative videotapes, which were retrospectively reviewed in order to allow detailed evaluation of the potential benefit of various acoustic EMG patterns in the performance of specific aspects of acoustic neuroma resection. The use of evoked facial EMG activity was classified and described. Direct local mechanical (surgical) stimulation and direct electrical stimulation were of benefit in the localization and/or delineation of the facial nerve contour. Burst and train acoustic patterns of EMG activity appeared to indicate surgical trauma to the facial nerve that would not have been appreciated otherwise. Early results of postoperative facial function of monitored patients are presented, and the possible value of burst and train acoustic EMG activity patterns in the intraoperative assessment of facial nerve function is discussed. Acoustic facial EMG monitoring appears to provide a potentially powerful surgical tool for delineation of the facial nerve contour, the ongoing use of which may lead to continued improvement in facial nerve function preservation through modification of dissection strategy.

Adult↗
PubMed1978

The opportunity for and significance of alteration of ribulose 1,5-bisphosphate carboxylase activities in crop production.

Increased population and the dietary changes accompanying increased affluence are creating a need for a suggested doubling of world cereal grain production (a 3% per year compounding rate) and quadrupling of grain legume production (a 6% per year compounding rate) during this quarter century (1). CO2 enrichment of field-grown crops has demonstrated the possibility of enhancing RuBP carboxylase activity to achieve improved crop production; it increases the production of grain legumes by 50 to 100% and that of cereal grains, for which the studies are less complete, by perhaps 10 to 50%. Results of O2 alteration of growth-room legumes and cereal grains are consistent with the results of CO2 enrichment except for a second role of O2 in assimilate partitioning. It may be necessary to include other components of the system, e.g., additional soil fertility, especially for non-N2-fixing plants, to enable an improved RuBP carboxylase to increase production. No practical method--chemical, genetic, or physical--of improving RuBP carboxylase activity has been reported.

Agriculture↗
PubMed1978

Dural arterio-venous malformations involving the cavernous sinus: a case report.

A case of dural arteriovenous malformation involving the cavernous sinus is reported. The patient was successfully treated with selective embolisation of the fistula. These patients constitute a distinct neuro-ophthalmological syndrome which may be very difficult to diagnose clinically because of the subtle signs and symptoms they present with. Angiography is necessary to make diagnosis and to differentiate these patients from those with the more common carotidcavernous fistulae.

Adult↗