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Biomedical subjects

M Horowitz

Publications and source records attributed to M Horowitz.

At least 469 records · Page 26Linked to original sources
PubMed1987

Biochemical effects of a calcium supplement in osteoporotic postmenopausal women with normal absorption and malabsorption of calcium.

Although calcium supplements are widely used to reduce bone resorption in osteoporosis, their beneficial effect is not conclusively established. We have studied the acute (after 12 h) effects of an oral calcium load (1 g) in a group of 35 osteoporotic postmenopausal women, comprising 19 subjects with normal absorption and 16 subjects with malabsorption of calcium. In the subjects with normal calcium absorption the fasting urinary total hydroxyproline/creatinine ratio fell from 0.021 to 0.017 (p less than 0.001), but in those with malabsorption of calcium it did not change significantly. This difference between the two groups was significant (p less than 0.01). These results indicate that an oral calcium load rapidly suppresses bone resorption in osteoporotic subjects with normal absorption of calcium, but not in those with malabsorption of calcium.

Aged↗
PubMed1987

Lateral idiopathic subluxation of the radial head. Case report.

Idiopathic subluxation of the radial head (ISRH) is a rare entity that is separate from congenital dislocations of the radial head, both symptomatically and radiographically. ISRH causes pain and restriction of rotation. A dome-shaped radial head, a hypertrophied ulna, and a hypoplastic capitellum are not present in ISRH, as they are in a congenital dislocation of the radial head (CDRH). A true lateral ISRH is used as an example to demonstrate these differences. Remodeling of the radial head may preserve motion in the joint surface deformed by growth along abnormal planes of motion.

Adult↗
PubMed1987

Complete acromioclavicular separations. A comparison of operative methods.

A retrospective study of the surgical treatment methods for complete acromioclavicular (AC) dislocations was initiated to investigate the efficacy of each. During the years 1972-1985, a total of 95 surgical procedures were performed for complete AC dislocations. The medical records of 90 cases were available for review. The operative methods compared coracoclavicular (CC) with AC fixation methods. Excision of the distal clavicle was performed for chronic dislocations. AC fixation methods included Kirschner wires alone, Kirschner-wire fixation with coracoacromial ligament transfer, and Kirschner-wire fixation with tension wiring. Results were graded using evaluation of pain, range of motion, and residual deformity. AC fixation methods proved to be more successful than CC fixation methods. Excellent results were obtained in more than 89% of both AC and CC methods. AC methods had more minor complications including infections and implant breakage, but no failure or recurrences of the dislocation. CC methods resulted in 9% failure or recurrences. Of the AC fixation methods, the Kirschner wire with tension wiring gave the best results but required a more extensive operation for removal of implants. Excision of the distal end of the clavicle is an adequate form of treatment for the chronic complete painful AC dislocation.

Acromioclavicular Joint↗
PubMed1987

Lactose and calcium absorption in postmenopausal osteoporosis.

The prevalence of lactase deficiency and the relationship between lactose and calcium malabsorption in postmenopausal osteoporosis has been assessed in 46 subjects. Malabsorption of lactose occurred in 25 (54%) of the subjects and was associated with a significantly lower milk intake. Malabsorption of calcium occurred in 11 (44%) of the lactase-deficient subjects and in 11 (52%) of normal lactose absorbers. There was no relationship between lactose and calcium malabsorption. Vertebral and forearm mineral densities were not significantly different between normal lactose absorbers and lactase-deficient subjects.

Aged↗
PubMed1987

Treatment of postmenopausal hyperparathyroidism with norethindrone. Effects on biochemistry and forearm mineral density.

The effects of norethindrone (5 mg daily) on biochemical variables and forearm mineral density were assessed in 20 postmenopausal women with mild primary hyperparathyroidism. Norethindrone produced a significant fall in plasma calcium levels and the fasting urinary calcium-creatinine and hydroxyproline-creatinine ratios after three months of treatment. There was no change in the plasma parathyroid hormone concentrations. The forearm mineral density before treatment was low in 16 of the 20 patients and there was a significant increase in forearm mineral density after norethindrone treatment. No side effects were reported. We conclude that norethindrone is an effective treatment for mild hyperparathyroidism in postmenopausal women.

Aged↗
PubMed1986

Immunosuppression in viral oncogenesis. III. Effects of virus infection on interleukin 1 and interleukin 2 generation and responsiveness.

Malignant rabbit fibroma virus (MV) is an oncogenic immunosuppressive leporipoxvirus. We studied the effects of MV infection and MV-associated tumor-induced suppressor factor (TISF) on the production of and responsiveness to interleukins 1 and 2. Adherent cells from MV tumor-bearing rabbits elaborate adequate amounts of IL 1 in response to E. coli endotoxin. Neither live virus nor TISF alters the production or the responsiveness to IL 1. However, when we examined spleen cells from rabbits 7 days after MV inoculation, we noted that their ability to produce and respond to IL 2 is deficient. Despite their relatively poor capacity to produce IL 2, these spleen cells express receptor for IL 2 in normal amounts, as measured by the monoclonal antibody 7D4. TISF derived from T lymphocytes from MV tumor-bearing rabbits is by itself capable of inhibiting partially normal secretion of IL 2 and also the response of the cloned murine T cell line HT-2 to added IL 2. Full expression of the immunosuppressive capacity of spleen cells from MV tumor-bearing rabbits requires cell-cell contact, however, and cannot be replaced by either live virus or spleen cell supernatants. Such spleen cells inhibit normal mitogen responsiveness, a defect not remedied by adding exogenous IL 2. Immunologic dysfunction induced by MV infection is transient, and by 11 days after virus inoculation, actively mediated recovery from immunosuppression is observed. We found that spleen cells from rabbits studied 11 days postinoculation secreted IL 2 normally. Thus, immunologic dysfunction secondary to infection with malignant rabbit fibroma virus reflects deficiencies in both elaboration of and response to IL 2, and return of immune function later in the course of the infection is associated with return of the ability of lymphocytes to secrete IL 2.

Animals↗
PubMed1986

Abnormalities of gastric and esophageal emptying in polymyositis and dermatomyositis.

Gastric and esophageal emptying were assessed using scintigraphic techniques in 13 patients with polymyositis or dermatomyositis and in 13 normal volunteers. Esophageal emptying was significantly delayed in patients, with 8 of 13 patients being outside the normal range. Gastric emptying was also markedly slower in patients than in controls, with 8 patients being outside the normal range for solid emptying and 8 patients beyond the normal range for liquid emptying. The 5 patients with dysphagia all had delayed esophageal emptying, but both gastric and esophageal emptying were delayed in some asymptomatic patients. There was a significant correlation between esophageal emptying and both solid and liquid gastric emptying in the patients. Both gastric and esophageal emptying correlated with the severity of the peripheral (skeletal) muscle weakness. These results indicate that profoundly delayed gastric and esophageal emptying are common in polymyositis and dermatomyositis, implying frequent malfunction of the smooth muscle of the upper gastrointestinal tract in this disease.

Adolescent↗
PubMed1986

Structure and activity of the translocated c-myc in mouse plasmacytoma XRPC-24.

In the mouse plasmacytoma XRPC-24 both c-mos and c-myc are rearranged. We cloned the rearranged c-myc and found that it was translocated to the immunoglobulin C alpha locus. The breakpoint is at the end of exon 1 in c-myc and approximately 0.5 kb upstream from exon 1 of C alpha. The cloned translocated c-myc linked to a strong transcriptional promoter can efficiently transform rat embryo fibroblasts when co-transfected with the activated Ha-ras. The transformed cells are tumorigenic in syngeneic rats.

Animals↗
PubMed1986

Comparison of calcium, calcitriol, ovarian hormones and nandrolone in the treatment of osteoporosis.

Most therapy for osteoporosis has been aimed at decreasing bone resorption and is capable of preventing further bone loss. Recently, anabolic steroids have been claimed to cause increased bone mass in osteoporosis, but the mechanism for this effect is not understood. In this study calcium, and calcium with calcitriol, caused a slowing of forearm bone mineral loss. Calcium and ovarian hormones, with or without calcitriol, caused a small non-significant rise in forearm mineral density, and nandrolone decanoate 50 mg intramuscularly, every 2 or 3 weeks caused a significant rise in forearm mineral density (+15.9 +/- 2.4 mg/ml/yr and +13.7 +/- 3.4 mg/ml/yr, respectively). The 3-weekly regime caused few side effects and is considered the optimal dose. The striking rise in bone density in patients in whom bone resorption was controlled before therapy, suggests that anabolic steroids can increase the bone formation rate.

Aged↗
PubMed1986

Alterations in cardiac myosin isoenzymes distribution as an adaptation to chronic environmental heat stress in the rat.

The distribution of cardiac myosin isoenzymes, using gel pyrophosphate electrophoresis, was studied in laboratory rats during acclimation to heat (34 degrees C, 0-2 month) with and without daily administration of triiodotyronin (0.3 micrograms/100 g b.wt) Thyroxin (T4) and triiodotyronin (T3) concentrations during that period were measured in the acclimated rats as well. Control rats exhibited only the V1 myosin form during the entire experimental period. In the heat acclimated rats, after three weeks of acclimation, in addition to the V1 band, bands of V2 and V3 myosin forms appeared. After the fourth week of acclimation V3 became the dominant myosin. Changes in the cardiac isoenzymes distribution occurred 1 week after a significant decrease in T3 was recorded. Administration of additional thyroxin dose didn't allow the development of V3 band in the heat acclimated rats. It was concluded that the changes observed in cardiac isoenzymes distribution could be related to an alteration in thyroid activity and that these changes could play a role in the adaptation of the cardiac muscle to chronic heat.

Acclimatization↗
PubMed1986

The long terminal repeat of the intracisternal A particle as a target for transactivation by oncogene products.

It has been shown recently that the c-mos oncogene becomes activated in myeloma XRPC-24 via insertion of an intracisternal A particle (IAP) long terminal repeat (LTR). The inserted LTR serves as a promoter from which transcription of the 3' rearranged c-mos initiates. The insertion is in a head-to-head orientation such that the transcriptional orientations of the IAP and the 3' rearranged c-mos are opposite. It has already been shown that this IAP LTR has two promoters, one transcribing the IAP genome and the other transcribing the rearranged c-mos. Since the IAP genomes are actively transcribed in mouse myelomas but not in normal cells, it was interesting to test whether transcriptional activation of the IAP occurs in the presence of active oncogene products, especially nuclear ones. The 5' LTR of the IAP inserted in myeloma XRPC-24 was chosen as a convenient model to test the effect of viral and cellular oncogene products. These included simian virus 40 (SV40) large-T antigen, the adenovirus early 1A (E1A) gene product, the myc gene product, and p53. The LTR was coupled to the bacterial gene coding for chloramphenicol acetyltransferase (CAT) in two orientations, and the levels of CAT directed by the LTR promoters were assayed in either the presence or the absence of the oncogene products. The levels of CAT directed by the 5' LTR promoter transcribing the IAP were significantly elevated in the presence of SV40 large-T antigen, the adenovirus E1A and myc gene products, and p53. The promoter transcribing the rearranged c-mos was transactivated by SV40 large-T antigen and the adenovirus E1A gene product. The results indicate that oncogene products may have an important role in turning on promoters of other genes. The IAP LTR may serve as a useful model for studying the effect of various gene products on promoters which are known to be activated in the malignant state.

Acetyltransferases↗
PubMed1986

Heat acclimation: cardiac performance of isolated rat heart.

Cardiac performance was studied in the isolated perfused hearts of rats heat acclimated at 34 degrees C (AC) and their age-matched controls (C). The pressure-volume curves during isovolumetric conditions showed a shift to the right in AC compared with C hearts. At similar left ventricular (LV) volumes end-diastolic and peak systolic pressures of AC hearts were lower, but no difference was observed in the maximal pressure developed at the highest LV volumes measured. In both C and AC hearts the developed force decreased as pacing rate increased. AC and C heart responses were the same up to 250 pulses/min. At higher frequencies the amplitude of the developed force of AC hearts was smaller than that of the controls. In accordance the tension produced by very early premature beat reduced in AC compared with C hearts. Since no hypertrophy was observed in AC hearts, it is concluded that heat acclimation results in a change in the intrinsic properties of the AC hearts exhibited by increased compliance, reduced chamber stiffness, and a decrease in the tension developed for each volume load. It is also suggested that at a high beating rate AC hearts fail to restitute its contractility as quickly as C hearts.

Acclimatization↗
PubMed1986

Gastric emptying after gastric bypass.

Gastric emptying of two test meals, consisting of ground beef and water and ground beef with 25 percent dextrose was measured with a scintigraphic technique in patients after gastric bypass surgery and in control subjects. Solid emptying was slower and liquid emptying was more rapid after gastric bypass and 25 percent dextrose emptied as rapidly as water. The pattern of gastric emptying after gastric bypass would favour more rapid initial absorption with liquid calories and may also be implicated in the dumping syndromes sometimes seen after gastric bypass.

Adult↗
PubMed1986

Effect of increasing the caloric/osmotic content of the liquid component of a mixed solid and liquid meal on gastric emptying in obese subjects.

A dual isotope scintigraphic technique was used to assess the effect of increasing the caloric content of the liquid component of a mixed solid and liquid meal on gastric emptying in control and obese subjects. For the two test meals used gastric emptying of solid was significantly slower in the obese subjects compared to the control subjects. In both obese and control subjects the substitution of 25 per cent dextrose for water as the liquid component of the meal resulted in a significant delay of both solid and liquid emptying. The magnitude of this change was similar in obese and control subjects. The results suggest that the duodenal receptor mechanisms which slow gastric emptying are not defective in obesity.

Adult↗
PubMed1985

Disorders of gastric emptying and the application of radionuclide techniques.

There has been a greatly increased understanding of the physiology of gastric emptying in normal subjects, and of the pathophysiology and pharmacological treatment of gastric emptying disorders associated with the development and application of methods to quantify gastric emptying in humans. The non-invasive measurement of gastric emptying by means of radionuclide-labelled food markers has widespread clinical and research applications.

Domperidone↗
PubMed1985

Regulation of submaxillary gland muscarinic receptors during heat acclimation.

Binding properties of submaxillary gland muscarinic receptors and agonist-induced saliva secretion were studied in rats subjected to heat acclimation. The maximal binding capacity for the muscarinic antagonist N-[3H]methyl-4-piperidyl benzilate was increased from control value of 0.21 to 0.40 pmol/mg protein within 1-2 days of heat acclimation. The increase in the number of muscarinic receptors per gland (100%) was by far higher than the increase in tissue weight (20%), indicating higher density of receptors in the acinar cells of the treated rats. High levels of receptors coincided with the appearance of high-affinity binding sites for muscarinic agonists (oxotremorine, pilocarpine and carbamylcholine), and with reduced tissue sensitivity to pilocarpine. After 4-8 weeks of heat acclimation, the number of receptors as well as tissue response to pilocarpine returned to control levels. These results suggest a functional correlation between the transient upregulation muscarinic receptors in the submaxillary gland and the physiological activity in salivary secretion, and indicate that the high-affinity muscarinic receptors may attenuate saliva secretion during the initial phase of heat acclimation.

Acclimatization↗