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Biomedical subjects

L Gentry

Publications and source records attributed to L Gentry.

26 records · Page 2Linked to original sources

Sensitive radioimmunoassay for vancomycin.

A radioimmunoassay for vancomycin has been developed which uses rabbit antiserum induced by vancomycin-bovine serum albumin conjugates and vancomycin labeled with 3H or 125I. Using either isotope, the method is simple and reproducible and has a sensitivity of 4 or 0.04 ng/ml, depending on the tracer used. This is 200- to 20,000-fold improvement in sensitivity compared with the most sensitive bioassay. Drug levels in serum or urine samples from patients receiving vancomycin can be determined by this assay procedure without processing. The data obtained with 3H and 125I labels were in good agreement. Patients' plasma vancomycin concentrations determined by radioimmunoassay correlated well with those determined by bioassay when the drug was administered intravenously. However, after oral administration the drug could be detected only by radioimmunoassay. The antiserum was evaluated for cross-reactivity with a wide variety of antibiotics and cancer chemotherapeutic agents, and no significant interference was found.

Animals↗

Nitration of polypeptides using ethanol in reaction buffers minimizes crosslinking.

High concentrations of ethanol are effective in reducing the intermolecular cross-linking which predominates when the reactions of tetranitromethane with the carboxypeptidase inhibitor from potatoes, a chymotrypsin inhibitor also from potatoes, and insulin are carried out under standard conditions. Including reagents such as ethanol may be of general utility in the preparation of monomeric nitro-derivatives of hydrophobic, low-molecular-weight proteins.

Buffers↗

MMPI criteria for diagnosing schizophrenia.

An attempt was made to find a combination of MMPI scale relationships which were highly discriminating of schizophrenia. Through the use of a standardized structured interview and a diagnostic system for schizophrenia based on the use of discriminant function analysis with nonpathognomonic symptom combinations, a reliable and valid system was used to establish the criterion diagnosis. Approximately 72% of patients reliably diagnosed as schizophrenics were detected on the MMPI via a set of standard criteria (T score on Sc greater than or equal to 80 less than or equal to 100; total raw score on Sc consisted of no more than 35% K items; T score on F greater than or equal to 75 less than or equal to 95; T score on Pt less than or equal to Sc). Only 5.5% of nonschizophrenics obtained all these standard criteria on the MMPI. The assets and liabilities of these MMPI criteria to diagnose schizophrenia are discussed.

Acute Disease↗

Ferromagnetic hyperthermia: functional and histopathologic effects on normal rabbit ocular tissue.

Ferromagnetic (FM) hyperthermia has previously been evaluated in a rabbit tumour model of ocular melanoma. To study the effect of focal heating in normal rabbit eyes, FM seeds were implanted into a 14-mm episcleral plaque an heated to operating temperatures of 48 or 58 degrees C. Thermal induction was performed by placing rabbits in a uniform, oscillating (11 kHz) magnetic field operating at 1200 W and as H-field strength of 265 A/m. Eyes were heated for 60 min with continuous scleral temperature monitoring. Hyperthermic effects were monitored by direct opthalmic examination, fundus photography, serial electroretinography and histopathology. Intraocular temperatures were mapped with direct fiberoptic thermometry. All treatment effects were confined to the area covered by the episcleral plaque. Direct ophthalmoscopic examination revealed early retinal whitening during heat induction followed by localized exudative retinal detachments, limited to the area of the retinal surface overlying the plaque, that resolved spontaneously. Serial electroretinography was virtually indistinguishable between the 48 and 54 degrees C temperature groups. We noted a minimal alteration in a- and b-wave amplitudes with no changes in implicit times. Histopathology at 3 weeks post-treatment documented chorioretinal scarring overlying the thermal plaque treatment zone. No evidence of heamorrhage infection, cataract or scleral thinning was noted. This study documents the apparent focal containment of thermal effects with FM heating utilizing operating temperatures ad high as 54 degrees C for 60 min, and discloses no evidence of diffuse ocular toxicity.

Animals↗