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Biomedical subjects

D Hardy

Publications and source records attributed to D Hardy.

At least 109 records · Page 6Linked to original sources
PubMed1967

The relation between heat produced and phosphorylcreatine split during isometric contraction of frog's muscle.

1. Heat production, tension development and phosphorylcreatine (PC) splitting have been measured simultaneously during isometric contractions of iodoacetate-poisoned frogs' sartorii at 0 degrees C. The muscles were stimulated to produce a series of 30 twitches or a 10 sec tetanus or a 30 sec tetanus.2. Of the several possible methods of calculating PC breakdown the best appears to be the one based on the assumption that PC/(total creatine) was originally the same in the two muscles of a pair.3. The difficulty of expressing PC break-down, heat production etc. in terms of the muscle's size is demonstrated.4. Several artifacts are discussed, including the heat produced by the stimulus and the possible role of reactions other than PC splitting.5. Even when these have been substantially eliminated there remains the rather intractable statistical problem of establishing a functional relationship between heat produced and PC split when both of these variables contain errors, so that ordinary regression analysis is misleading. It is shown that this problem can be dealt with satisfactorily by introducing other instrumental variables that can be determined experimentally.6. The final conclusion is that the in vivo enthalpy of hydrolysis of PC is about 10.6 kcal/mole, and is the same in twitches and in tetani.

Animals↗
PubMedDate not supplied

Efficacy and safety of adefovir dipivoxil with antiretroviral therapy: a randomized controlled trial.

CONTEXT: Adefovir dipivoxil is a nucleotide analog that has demonstrated effective antiretroviral activity against human immunodeficiency virus (HIV) with once-daily administration. OBJECTIVE: To determine if adefovir confers antiretroviral or immunologic benefit when added to stable antiretroviral therapy. DESIGN: Multicenter, 24-week, randomized, double-blind, placebo-controlled study. Enrollment was conducted from June 3, 1996, through May 6, 1997. SETTING: Thirty-three US HIV treatment centers. PARTICIPANTS: Of 1171 patients screened, 442 patients infected with HIV receiving stable antiretroviral therapy for at least 8 weeks with plasma HIV RNA greater than 2500 copies/mL and CD4+ cell count above 0.20 x 10(9)/L were randomized. INTERVENTION: Patients were randomized to receive either a single 120-mg/d dose of adefovir dipivoxil (n = 219) or an indistinguishable placebo (n = 223). All patients received L-carnitine, 500 mg/d. Open-label adefovir was offered after 24 weeks and was continued until the end of the study. MAIN OUTCOME MEASURES: Changes in HIV RNA from baseline, based on area under the curve and CD4+ cell levels, adverse events, and effect of baseline genotypic resistance on response to adefovir. RESULTS: Patients assigned to adefovir demonstrated a 0.4-log10 decline from baseline in HIV RNA compared with no change in the placebo group (P<.001), which continued through 48 weeks. CD4+ cell counts did not change. During the initial 24 weeks, elevated hepatic enzyme levels (P<.001), gastrointestinal tract complaints (P<.001), and weight loss (P<.001) were associated with use of adefovir. Between 24 weeks and 48 weeks elevations in serum creatinine occurred in 60% of patients, usually returning to baseline after discontinuation of adefovir. Patients with lamivudine or lamivudine and zidovudine resistance mutations demonstrated anti-HIV effects with adefovir (P< or =.01 vs placebo group). CONCLUSIONS: This study suggests that once-daily adefovir therapy reduces HIV RNA and is active against isolates resistant to lamivudine or lamivudine and zidovudine. Nephrotoxicity occurred when treatment extended beyond 24 weeks but was reversible.

Adenine↗
PubMedDate not supplied

Time trends in human dietary exposure to PCDDs, PCDFs and PCBs in the UK.

Total Diet Study samples collected in 1982 and 1992 were analysed. Estimated dietary intakes of PCDDs, PCDFs and PCBs by UK consumers were found to have fallen substantially during this period and are now considerably below the Tolerable Daily Intake (TDI). Composite samples of human milk were also analysed for PCDDs, PCDFs and PCBs. Estimated combined dietary intakes of PCDDs, PCDFs and PCBs by breast fed infants in 1993-94 via breast milk fell from 170 pg TEQ/kg bodyweight/day at 2 months to 39 pg TEQ/kg bodyweight/day at 10 months.

Adolescent↗
PubMedDate not supplied

Different aspects of the cyclops lesion following anterior cruciate ligament reconstruction: a multifactorial etiopathogenesis.

After anterior cruciate ligament (ACL) reconstruction using a patellar-tendon autograft, 65 patients underwent second-look arthroscopy in conjunction with hardware removal. In 23 patients, hypertrophic tissue was found in the anterior part of the knee. This tissue presented different aspects, from a well-synovialized nodule to a more disorganized fibrous tissue according to patients' complaints. Endoscopic resection of this offending tissue was generally sufficient to obtain a satisfactory result. In patients presenting a loss of extension, the notch frequently had to be enlarged. We have found a multifactorial pathogenesis to be likely: the nodule is a natural fibroproliferative tissue process originating either from drilling debris from the tibial tunnel or from remnants of the ACL stump and, more rarely, from broken graft fibers. Sometimes, when the graft is malpositioned, the scar tissue can result from repeated graft impingement on the notch at terminal extension. Formation of this aberrant tissue should be prevented by proper positioning of the graft, by enlargement of the narrowed notch in chronic cases, by using drills of increasing diameters to avoid production of osteocartilaginous fragments, by meticulous resection of all drilling debris and ACL remnants around the tibial tunnel, and by enlarging the notch roof if any contact with the graft is present when the knee is fully extended intraoperatively.

Adult↗
PubMedDate not supplied

Computed tomography measurement of humeral head retroversion: influence of patient positioning.

For accurate humeral head arthroplasty, the surgeon needs to know some geometric data, such as, for example, the retroversion angle of the humeral head. Only a few reports have described and evaluated the use of computed tomography (CT) to measure humeral head retroversion. The humerus position relative to the roentgen beam is variable from one subject to another depending on the patients' morphology. It could influence the retroversion measurement and has not been investigated previously. This study analyzes in 9 cadaver humeri the variability of retroversion angle measurements with different humerus positioning relative to the roentgen beam during CT examination. The truest retroversion angle can be obtained when true axial slices, perpendicular to the humeral diaphysis, are obtained. Our study tries to clarify technical problems that occur during CT examination. Geometric considerations that can modify the measurements are presented. A reliable method of humeral head retroversion angle measurement is recommended, which could be useful to the shoulder surgeon.

Arthroplasty, Replacement↗
PubMedDate not supplied

Quantitative determination of phenelzine in human fluids by gas chromatography with nitrogen specific detection.

A quantitative gas chromatographic assay for the determination of phenelzine in plasma or other fluids is presented. A stable derivative is formed by cyclization with acetylacetone, and the derivative is separated, purified, and concentrated by liquid-liquid solvent extraction. Analysis of the extracts is by capillary gas chromatography with nitrogen specific detection. Detection limits of less than 1 ng/mL and CVs of 5% at the 10-ng/mL level are attainable with a 2-mL sample and benzylhydrazine as the internal standard.

Body Fluids↗