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Biomedical subjects

H Kaufman

Publications and source records attributed to H Kaufman.

At least 55 records · Page 3Linked to original sources
PubMed1986

Intraoperative length and tension curves of human eye muscles. Including stiffness in passive horizontal eye movement in awake volunteers.

Intraoperative continuous-registration length and tension curves of attached and detached eye muscles were made in 18 strabismic patients under general anesthesia. For relaxed eye muscles, we found an exponential relation between length and tension. An increased stiffness was quantified in Duane's syndrome, Graves' disease, orbital-floor fracture, and superior oblique palsy. The stiffnesses of agonist and antagonist were remarkably similar, not only in uncomplicated squint, but also when only one of the two had initially become stiffer. After intravenous administration of succinylcholine chloride, the eye muscles contracted, and the exponential length and tension curve changed into a set of straight, parallel lines. In addition, we measured stiffness in passive horizontal eye movement in awake volunteers and found 0.52 to 1.26 g/degrees (other eye in 5 degrees of adduction), confirming other published results.

Adult↗
PubMed1986

Acetylcholinesterase: theory of noncompetitive inhibition.

The theory of noncompetitive inhibition of acetylcholinesterase based on the binding of inhibitor to the acetylenzyme and the free enzyme was proven correct by demonstrating that tripropylammonium ion increases the steady-state concentration of acetylenzyme, as predicted by the theory. By contrast, the traditional theory that the inhibitor binds to the enzyme-substrate complex and the free enzyme predicts that the amount of acetylenzyme will be drastically reduced when the inhibition is high. A third theory involving all three types of binding remains possible.

Acetylcholinesterase↗
PubMed1986

Histochemistry of adenylate cyclase activity in the anterior segment of the eye: a methodological evaluation with biochemical background.

A histochemical technique for adenylate cyclase activity suitable for both light and electron microscopy is described. This technique is based on the Sr2+ capture reaction using adenylylimidodiphosphate as the substrate. The precipitated strontium phosphate is converted to lead phosphate, which is electron-dense for electron microscopy and can also be made visible by light microscopy. Different fixatives and fixation times were tested; paraformaldehyde at a concentration of 1% for 5 min demonstrated the enzyme activity best. The enzyme was protected and-or stimulated during all stages with isoproterenol, 5-guanylylimidodiphosphate, and dimethyl sulfoxide (DMSO). Numerous capturing agents (Pb2+, Co2+, Ce2+, Ba2+, Cd2+, and Sr2+) were tested. Strontium chloride (10 mM) produced the best result, inhibiting the enzyme less than 50%. The others gave inconsistent results. By this technique, adenylate cyclase activity was localized on the cell membranes of the deep layers of the rabbit corneal epithelium, on the endothelium, and on the cell membranes of the non-pigmented epithelium in the ciliary processes. These sites correspond well with earlier autoradiographic localization of beta-adrenergic receptors in the rabbit eye.

Adenylyl Cyclase Inhibitors↗
PubMed1986

Cushing's disease coexisting with a single macronodule simulating adenoma of the adrenal cortex.

A rare case of Cushing's disease coexisting with a single macronodule simulating adenoma of the adrenal cortex is presented. The basal and dynamic tests supported the diagnosis of Cushing's disease, whereas the CT-scan, ultrasound and iodocholesterol uptake were suggestive of a left adrenal adenoma. Treatment consisted of extirpation of the nodular gland followed by pituitary irradiation. The examination revealed a single macronodule with no histological membrane, surrounded by hyperplastic adrenocortex. Together with the three similar ones reported in the literature this case suggests that nodular hyperplasia may be an intermediary stage between diffuse hyperplasia and the appearance of an autonomous adenoma after long-term stimulation of the hyperplastic gland.

Adenoma↗
PubMed1985

Beta-endorphin in normozoospermic and pathologic human semen.

beta-Endorphin was estimated in normozoospermic, oligozoospermic and azoospermic human semen. The mean amount in normozoospermic specimens was 278.6 +/- 43.6 (SE) pg/ml while in the others only 191.1 +/- 25 pg/ml. Both values are significantly higher than those present in the blood.

Adult↗
PubMed1985

Hypertension in a neonate with 11 beta-hydroxylase deficiency.

A female newborn infant with ambiguous genitalia was found to have hypertension (121/82 mm Hg) immediately after birth. The plasma testosterone (T) (0.73 nmol/l), delta 4-androstenedione (delta 4-A) (5.9 nmol/l), dehydroepiandrosterone (DHEA) (8.9 nmol/l), as well as 17 OH-hydroxyprogesterone (17 OHP) (152 nmol/l) were elevated. The diagnosis of 11 beta-hydroxylase deficiency was finally established on the basis of elevated plasma eleven-deoxycortisol (compound S) (greater than 0.6 mumol/l) and confirmed by the normalisation of the blood pressure during hydrocortisone therapy. Our case is probably the youngest patient with 11 beta-hydroxylase deficiency in whom the hypertension was found at birth.

Adrenal Hyperplasia, Congenital↗
PubMed1985

Pseudotumor cerebri in a boy with 11-beta-hydroxylase deficiency--a possible relation to rapid steroid withdrawal.

A boy who was known to suffer from adrenogenital syndrome due to 11-beta-hydroxylase deficiency was treated with appropriate steroid replacement, which fully compensated for the deficiency. An intercurrent febrile illness with anorexia and vomiting necessitated an abrupt discontinuation of steroids. He presented with classic signs of pseudotumor cerebri 3 days following steroid withdrawal. Our studies imply that a combination of steroid withdrawal and dehydration with increased sodium urinary excretion, caused rapid fluid shifts within the brain, resulting in intracranial hypertension. At present, when a considerable number of children are on long-term steroids for various reasons, pseudotumor cerebri should be considered in the list of complications during abrupt steroid withdrawal.

Adrenal Hyperplasia, Congenital↗
PubMed1985

Mechanical and metallurgical properties of carotid artery clamps.

The mechanical and metallurgical properties of carotid artery clamps were evaluated. The pressure plate retreat propensity, metallurgical composition, surface morphology, magnetic properties, and corrosion resistance of the Crutchfield, Selverstone, Salibi, and Kindt clamps were tested. None of the clamps showed evidence of pressure plate retreat. The clamps differed significantly in their composition, surface cleanliness, magnetic properties, and corrosion resistance. The Crutchfield clamp was the only one manufactured from an ASTM-ANSI-approved implantable stainless steel (AISI 316) and the only clamp in which the surfaces were clean and free of debris. The Selverstone clamp was made principally from AISI 304 stainless steel, as was one Salibi clamp. The pressure plate on another Salibi clamp was made from a 1% chromium and 1% manganese steel. Machining and surface debris consisting principally of aluminum, silicon, and sulfur was abundant on the Selverstone and Salibi clamps. The Kindt clamp was manufactured from AISI 301 stainless steel with a silicate-aluminized outer coating. The Crutchfield and Selverstone clamps were essentially nonferromagnetic, whereas the Salibi and Kindt clamps were sensitive to magnetic flux. In the pitting potential corrosion test, the Crutchfield clamp demonstrated good corrosion resistance with a pitting potential of 310 mV and no surface corrosion or pitting by scanning electron microscopy examination. The Selverstone clamp had lower pitting potentials and showed various degrees of corrosion and surface pitting by scanning electron microscopy. The Salibi pressure plate had a very low pitting potential of -525 mV and showed severe corrosion. By metallurgical criteria, only the Crutchfield clamp is suitable for long term implantation.

Animals↗
PubMed1984

Total deficiency of corticosteroid-binding globulin.

An obese 15-year-old boy of Jewish Iranian origin who is the offspring of consanguineous parents was found to have very low levels of total cortisol in the plasma. Investigation of the family revealed a complete lack of cortisol-binding-globulin (CBG) in the proband and a sister, evidently the first cases of total CBG deficiency to be reported. The parents and a brother were found to have half the normal levels. This study indicates that CBG deficiency, a benign condition, is compatible with a codominant or recessive autosomal trait inheritance.

Adolescent↗
PubMed1984

Treatment of precocious puberty with LHRH analogue in combination with cyproterone acetate-further experience.

Six girls and one boy with precocious puberty were treated with a superactive LHRH analogue (D-TRP6-LHRH) for periods ranging from 1 year to 2 years and 3 months. In the first phase of the treatment it was administered in combination with cyproterone acetate (CyA) to counteract an early stimulatory effect until inhibition of gonadotrophin secretion was achieved. The gonadotrophin-dependent signs i.e. gonadarche, showed sustained arrest and even regression. Gonadal sex steroids decreased but the adrenal androgens were unaffected. In four patients who showed progression of the angrogen-dependent signs (adrenarche), despite suppression of gonadotrophins, increasing the dosage of the LHRH analogue was ineffective and combined therapy with CyA was reinstituted in three of them because of accelerated growth and bone maturation. It is concluded that at present the treatment of choice for precocious puberty is the daily administration of a superactive LHRH analogue such as D-TRP6-LHRH, together with CyA in the initial stage, and at a later state if adrenarche progresses too rapidly.

Androgens↗
PubMed1984

Protein synthesis rates in rats with portacaval shunts.

Protein synthesis rates were measured (33 days postoperatively) in rats with portacaval shunts and in unoperated controls. In brain, no change in the rate of protein synthesis was evident in shunted rats. These data thus do not support the hypothesis that an inhibition of brain protein synthesis is a factor in the etiology of hepatic encephalopathy. The synthesis rate in forebrain at 82 days of age was 0.52%/h. Though brain wet weight was the same in both groups, rats with shunts grew relatively slowly, and their testicles probably decreased in weight. However, no inhibition of muscle, liver, or testicular protein synthesis could be detected. The mechanism of slower or negative growth in these tissues might thus involve an increase in the degradation rate, although a transient inhibition of synthesis at an earlier period is also possible.

Animals↗