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Biomedical subjects

H P Cohen

Publications and source records attributed to H P Cohen.

At least 19 recordsLinked to original sources
PubMed1993

Endodontic anesthesia in mandibular molars: a clinical study.

Sixty-one mandibular molar teeth with clinically manifest pulpitis, which required endodontic therapy, were studied. Twenty-seven subjects received standard inferior alveolar nerve block (IANB) with 2% lidocaine HCI with 1:100,000 epinephrine and 34 subjects received IANB with 3% mepivacaine with no vasoconstrictor. Pulpal anesthesia was assessed with dichlorodifluormethane (DDM). Subjects who gave a positive response to DDM were given a periodontal ligament injection with 2% lidocaine with 1:100,000 epinephrine. This study showed that 3% mepivacaine HCI is as effective as 2% lidocaine HCI in achieving pulpal anesthesia in mandibular molars with IANB. Of a total 61 IANB with lip anesthesia, 23 subjects required periodontal ligament injection to achieve a negative response to DDM. It was concluded that lip anesthesia is not a reliable indicator of pulpal anesthesia. The use of DDM is a reliable method of determining true pulpal anesthesia.

Anesthesia, Dental↗
PubMed1986

High-performance liquid chromatographic separation of leghemoglobins from soybean root nodules.

A crude fraction of soybean nodule ferri-leghemoglobin was absorbed onto a commercial DEAE HPLC column at pH 8.0, and resolved into eight isoprotein fractions. The identity of the leghemoglobins were determined by their order of elution from the DEAE column and by isoelectric focusing, using isoprotein standards isolated by conventional procedures. The three isoproteins of the c complex, c1, c2, c3, were not resolved. Unexpected heme containing proteins eluted just after leghemoglobin a and the c complex. These components possessed proteins similar to leghemoglobin a and the c complex, respectively, as judged by isoelectric focusing and absorbance spectra of the ferri and ferrous forms. The components designated leghemoglobin a' and leghemoglobin c' were also differentiated from leghemoglobin a and c by reverse-phase HPLC in a C18 column. Amounts of protein for the DEAE HPLC column ranged from 10 micrograms to 20 mg and sample volumes ranged from 2 to 250 microliters. The time required for chromatography varied depending on the gradient used, but never exceeded 40 min for samples up to 5 mg protein or 120 min for samples containing 5 to 20 mg protein. Due to the sensitivity of detection at 403 nm and leghemoglobins being the predominant chromophore at that wavelength, it was possible to quantitate levels of individual leghemoglobins in samples extracted from single nodules (ca. 15 to 65 mg fresh weight tissue). Quantitation was performed by interfacing the spectrophotometer output (10 mV) to a microcomputer and using commercially available software.

Chromatography, High Pressure Liquid↗
PubMed1986

Biochemistry of fern spore germination: protease activity in ostrich fern spores.

Protease activities were detected in quiescent and germinating spores of the ostrich fern (Matteuccia struthiopteris [L.] Todaro). Peak endopeptidase, aminopeptidase, and carboxypeptidase activities were detected 12 to 24 hours after spores began imbibing under light. There was a correlation between activities of proteases, the onset of a decline in levels of soluble protein, and an increase in levels of free amino acids. The earliest visible event of spore germination, breakage of the spore coat and protrusion of a rhizoid cell, was observed after peak protease activity, 48 to 72 hours after the start of imbibition. Results of this study demonstrate similarities in the pattern of protease activities during germination of ostrich fern spores to those of some seeds.

Journal Article↗
PubMed1975

Patterns of clinical response and plasma dopa levels in Parkinson's disease.

Serial determinations of plasma dihydroxyphenylalanine (dopa) in 16 Parkinson's disease patients receiving levodopa showed a negative correlation between plasma dopa levels and disability scores among patients who exhibited daily fluctuations of signs and symptoms. This suggests that the amount of levodopa delivered to the brain from the periphery is of major importance in the production of the "on-off" phenomenon. A close relationship between plasma dopa levels and abnormal involuntary movements was present in six patients. In three a striking dissociation between control of Parkinson's disease and abnormal involuntary movements was present, suggesting that in some patients these two effects are mediated through different underlying mechanisms. Administration of levodopa in such a way as to prevent both high and low levels of dopa in plasma minimizes disability in Parkinson's disease and may lessen abnormal involuntary movements in patients with the "on-off" effect.

Adult↗
PubMed1975

Catecholamine content of cerebral tissue after occlusion or manipulation of middle cerebral artery in cats.

The authors determined by fluorimetry the norepinephrine-epinephrine content (NE-E) of cerebral tissue from 38 cats, to ascertain whether constriction of hypersensitive arterial vessels by vasoactive agents in ischemic cerebral tissue could cause extension of cerebral infarcts and worsening of neurological deficits. Twenty-three cats had the left middle cerebral artery (MCA) occluded transorbitally, and 10 cats had sham operations. Five cats had only the surgical procedures necessary for obtaining tissue; mean NE-E content was 0.30 mug/gm (SD=0.041). For the other 33 cats, including those with sham operations, values were variable, ranging from 0.07 to 0.60 mug/gm. Low values usually were obtained for ischemic hemispheres 24 hours and 7 days after MCA occlusion, but at other times values could be high or low on either side. Many factors unrelated to tissue damage, including arterial manipulation, influence the catecholamine content of cerebral tissue.

Animals↗