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Biomedical subjects

R Marcus

Publications and source records attributed to R Marcus.

At least 235 records · Page 13Linked to original sources
PubMed1987

Normal and abnormal bone remodeling in man.

Remodeling is a continuous process of skeletal destruction and renewal, occurring throughout life in humans and some other mammals. Remodeling minimizes the damage of routine wear but, because of its fundamental inefficiency, also underlies normal age-related bone loss. Alterations in bone mass due to dietary and endocrine factors occur in response to changes in the birthrate of new remodeling units, increased remodeling imbalance within existing units, or a combination of both. Familiarity with remodeling is prerequisite to understanding the pathologic basis and rational therapy of metabolic bone disease.

Adult↗
PubMed1986

Bone marrow transplantation for patients with chronic myeloid leukemia.

Between February 1981 and December 1984 we treated 52 patients with chronic myeloid leukemia in the chronic phase and 18 patients with more advanced disease by high-dose chemoradiotherapy followed by allogeneic bone marrow transplantation using marrow cells from HLA-identical sibling donors. In addition, the 40 patients who had not previously undergone splenectomy received radiotherapy to the spleen. To prevent graft versus host disease, cyclosporine was given either alone or in conjunction with donor marrow depleted of T cells. Of the 52 patients treated in the chronic phase, 38 are alive after a median follow-up of 25 months (range, 7 to 50); the actuarial survival at two years was 72 percent, and the actuarial risk of relapse was 7 percent. Of the 18 patients with more advanced disease, 4 have survived; the actuarial two-year survival was 18 percent, and the actuarial risk of relapse was 42 percent. We conclude that the probability of cure is highest if transplantation is performed while the patient remains in the chronic phase of chronic myeloid leukemia. T-cell depletion may have reduced the incidence and severity of graft versus host disease. The value of irradiation to the spleen before transplantation has not been established.

Adolescent↗
PubMed1986

Natural history of histiocytosis X: a Pediatric Oncology Group Study.

The best therapy for patients with histiocytosis X with disease involvement other than isolated bone lesions but without organ dysfunction is unclear. This retrospective study was undertaken to define the natural history of this group of patients. In 25 of the 92 studied patients, there was no progression of the disease after diagnosis. In 53 surviving patients, the disease either continuously progressed (40) or recurred intermittently (13). The onset of last disease activity was 24 months or less for 55% of these children. A fatal outcome occurred in 14 children. All of these children developed organ dysfunction and 11/14 died during or before the second year of disease. These three different outcomes could not be predicted from the parameters evaluated; however, the disease that never abated but was continuously active was associated with a suboptimal outcome, and the development of organ dysfunction was a grave prognostic sign.

Adolescent↗
PubMed1986

Interactions of medroxyprogesterone acetate with estrogen on the calcium-parathyroid axis in post-menopausal women.

We studied the effect of medroxyprogesterone acetate (MPA) as a single agent and in combination with conjugated equine estrogens (E), on the calcium-parathyroid axis in healthy post-menopausal women. Twenty-six subjects, 2-22 yr post-menopause, were studied under basal conditions, and then following 10 days of MPA (10 mg/day), 30 days of E (0.625 or 1.25 mg/day), and an additional 10 days of E + MPA. As predicted, E decreased urinary excretion of calcium and hydroxyproline. MPA did not alter these excretion variables, either when given alone, or when added to E. Cyclic administration of MPA for 10 days is currently advocated to avoid the adverse endometrial consequences of unopposed estrogen. These data indicate that such a program does not interfere with the beneficial effect of estrogen on the calcium-parathyroid axis.

Adult↗
PubMed1986

Short-term effects of calcium carbonate, lactate, and gluconate on the calcium-parathyroid axis in normal elderly men and women.

We evaluated the impact of three calcium salts on the calcium-parathyroid axis in healthy elderly volunteers. Fasting subjects were administered a standardized 1-g calcium load on three occasions, using calcium carbonate, lactate, and gluconate in random sequence with 8 oz milk or orange juice as carrier. Blood and urine were collected at baseline and for 6 h following the calcium load. Each salt rapidly increased the serum-calcium concentration and urinary-calcium excretion. Response duration was shorter with gluconate than with the other salts, but peak responses were similar for all preparations. Urinary-calcium excretion was slightly lower when orange juice replaced milk, but calcemic responses were not different. Changes in immunoreactive-parathyroid hormone and renal-phosphorus handling did not differ among calcium salts. Except for a shorter duration of effect with gluconate, all three calcium salts provided similar short-term suppression of the parathyroid axis.

Aged↗
PubMed1986

Techniques and applications of sphenoidal recording.

Sphenoidal electrodes were introduced in the late 1940s and early 1950s to record EEG activity from the inferior mesial temporal region. They are inserted percutaneously beneath the zygomatic arch to rest in the vicinity of the foramen ovale. They are safe, easy to insert, and well tolerated for up to 3 weeks. Artifacts are less prominent than with other types of basal electrodes. Complications are rare. Sphenoidal electrodes are superior to scalp electrodes in detecting interictal epileptiform discharges and ictal EEG patterns from the inferior mesial temporal lobe. Clinical indications include: documentation of epileptiform activity in patients with partial complex seizures in whom scalp recording has been inconclusive; diagnosis of episodes of uncertain mechanism; and localization of an epileptogenic focus in patients being evaluated for temporal lobectomy.

Barbiturates↗
PubMed1986

Milk-alkali syndrome in patients treated with calcium carbonate after cardiac transplantation.

Heart and heart-lung transplant recipients at Stanford (Calif) University Medical Center were routinely prescribed long-term calcium carbonate antacid therapy to aid in the prevention of peptic ulcer disease and osteoporosis associated with glucocorticoid immunosuppressive therapy. Patients consumed 4 to more than 10 g/d of elemental calcium. Since calcium carbonate also provides the essential ingredients for the development of the milk-alkali syndrome, the laboratory flow sheets of 297 heart and heart-lung transplant recipients were reviewed to examine the incidence of hypercalcemia. Sixty-five patients developed significant hypercalcemia after transplantation. Thirty-one patients were alkalotic at the time of hypercalcemia; 37 had impairment in renal function. It is likely that most of these patients had the milk-alkali syndrome. While most patients became eucalcemic by discontinuing calcium carbonate therapy, intravenous hydration and forced diuresis were used to treat severe cases. It is possible that the incidence of the milk-alkali syndrome will increase with the current popularity of prescribing calcium carbonate for the prevention and treatment of osteoporosis.

Adult↗
PubMed1986

Aberrant expression of HLA-DR antigen on valvular fibroblasts from patients with active rheumatic carditis.

Immunofluorescence and immunoperoxidase staining was used to investigate the expression of Class II major histocompatibility antigens in myocardial tissue of 16 patients with acute rheumatic carditis. Aberrant expression of HLA-DR was examined using monoclonal anti-Ia antibodies and was detected on the valvular fibroblasts of those valves with ongoing active carditis. Sections of myocardial and valvular tissue from normal controls or from patients dying of other cardiac diseases did not express HLA-DR. The aberrant expression of HLA-DR on valvular fibroblasts could be important in triggering autoimmune destruction in that these cells could present self-antigens to sensitized T-lymphocytes which could initiate autoantibody production or direct destruction of local tissue.

Acute Disease↗
PubMed1985

Plasma cyclic AMP response to calcitonin: a potential clinical marker of bone turnover.

A noninvasive marker of bone turnover would be useful in predicting which patients are at risk of rapid bone loss and in monitoring response to therapy. Calcitonin (CT)-induced hypocalcemia correlates with bone turnover but has not been a clinically useful test because changes in serum calcium are small, and test duration is long. CT rapidly increases plasma cAMP levels. We conducted studies in rats and in man to characterize the origin of this rise, and to determine its suitability as a potential clinical marker of bone resorption. Administration of CT to rats resulted in a prompt and sustained rise in plasma cAMP. This effect was not blunted by nephrectomy and was greater in calcium-deprived rats with increased bone resorption. Thus, it appears to reflect CT action on bone. An intramuscular injection of 100 units salmon CT elevated plasma cAMP in 18 normal men and women. This effect was observed by 20 min after injection and persisted over 2 h. Although basal levels of plasma cAMP were similar in healthy postmenopausal women and men, the response to CT was greater in women. The response of women with hyperparathyroidism was greater than that of normal women, and the response of pagetic men was greater than that of normal men. The rise in plasma cAMP following CT is rapid and easily measured and appears to correlate with the state of bone remodeling. Additional studies will be required in osteoporotic subjects with high and low remodeling activity before the clinical utility of this test can be determined.

Aged↗
PubMed1985

Determinants of bone gamma-carboxyglutamic acid-containing protein in plasma of healthy aging subjects.

The gamma-carboxy glutamic acid (Gla)-containing protein of mammalian bone (BGP, also called osteocalcin) is a 49 amino acid polypeptide containing two to three residues of gamma-carboxyglutamic acid. BGP is synthesized by osteoblastlike cells, and plasma BGP in laboratory animals is derived principally from recently synthesized BGP. These data, taken together with observations that plasma BGP levels are elevated in patients with disorders of high bone turnover, suggest that plasma BGP is a marker of osteoblast activity. Since low bone formation rates may play an important role in the loss of bone mass with age, we have examined the determinants of plasma BGP levels in aging subjects, using a region-specific radioimmunoassay for human BGP based on the synthetic C-terminal peptide hBGP37-49. In 147 carefully screened healthy subjects, aged 23-91, BGP did not change with age, whereas alkaline phosphatase (AP) showed a significant positive correlation (r = 0.30, P less than 0.001). Creatinine clearance (GFR) declined by 0.9 ml/min/yr and correlated with both BGP (r = -0.21, P less than 0.001) and AP (r = -0.21, P less than 0.001). However, correlation of AP with age persisted after controlling for GFR. BGP was not correlated with serum PTH, urine Ca/GFR, or urine cAMP/GFR. In 48 patients with known parenchymal renal disease studied for comparison, plasma BGP was increased at a serum creatinine of greater than or equal to 1.8 mg/dl. Our results indicate that plasma BGP, a specific marker of bone metabolism, is not predictably related to age per se. This result is in contrast to the age-related rise in total AP. Subtle changes in renal function can affect plasma BGP levels.

1-Carboxyglutamic Acid↗
PubMed1985

Bone mineral density in the femoral neck: quantitative assessment using dual-energy projection radiography.

Two different dual-energy projection radiography techniques were used to quantitate bone mineral density in the femoral neck. A heterogeneous population of normal aging individuals of both genders was studied. Using a dual-energy scanned projection method, femoral neck mineralization was shown to decline with age in men and women with normal endocrine status, and to correlate positively with serum calcium level in women and both genders combined. No significant relation to incidence and severity of vertebral body compression fractures, the Singh trabecular index, glomerular filtration rate, urinary calcium excretion, plasma levels of vitamin D, parathyroid hormone, or alkaline phosphatase was demonstrated. According to both methods, femoral neck density tended to be higher in taller and heavier subjects. Although it may not be possible to predict accurately the occurrence of femoral neck fracture in a given individual, dual-energy scanned projection radiography appears to be useful in determining mineral status of the site at risk.

Adult↗
PubMed1985

Menstrual function and bone mass in elite women distance runners. Endocrine and metabolic features.

Bone mass and metabolic features were studied in 17 women distance runners. Eleven of the women had secondary amenorrhea for 1 to 7 years. Six women have maintained regular menses since menarche. Both groups were matched for aerobic capacity, body fat, exercise intensity, and age of menarche. Mineral density of lumbar spine in the amenorrheic runners was lower than that in the cyclic women and age-matched controls, but higher than that in runners with secondary amenorrhea who are less physically active. Mineral density of the radius was normal in both groups. Running-related fractures were more frequent in amenorrheic women. Metabolic assessment showed no differences between groups, except that serum triiodothyronine was lower in the amenorrheic group, perhaps reflecting low calorie intake. Intense exercise may reduce the impact of amenorrhea on bone mass; however, amenorrheic runners remain at high risk for exercise-related fractures.

Adolescent↗
PubMed1985

Comparison of performance for leukocyte differential counting of the Technicon H6000 system with a manual reference method using the NCCLS standard.

The National Committee for Clinical Laboratory Standards (NCCLS) has published a tentative standard for leukocyte differential counting, by means of which a manual or automated method for leukocyte differential counting can be compared with a manual reference method. The performance of the Technicon H6000 system was evaluated using the standard at Stamford and Overlook Hospitals. A total of 502 patient samples were analyzed: 315 from Overlook and 187 from Stamford. The H6000 system was found to be approximately four times more precise than the 200-cell manual reference method for each cell type. Correlation of the H6000 system with the manual method was good, with correlation coefficients of 0.98 for neutrophils and lymphocytes, 0.96 for eosinophils, 0.72 for monocytes, and 0.5 for basophils. The clinical sensitivity of the H6000 system, measured in terms of false normals and false abnormals, was similar to that of the manual reference method when measured against itself. There were no clinically significant discrepancies in results from the H6000 system, except for possibly one case where a patient was already on antibiotic therapy. The NCCLS standard was found to be a useful but rather complex and involved method for evaluating the performance of the H6000 system, the major problem being the amount of work needed to count manually the number of cells required for the manual reference method.

Diagnostic Errors↗
PubMed1984

The effect of amylose content on insulin and glucose responses to ingested rice.

We evaluated the effect of amylose and amylopectin content on the glucose and insulin responses to rice. Thirty-three normal volunteers were given three types of rice containing 0, 14 to 17, or 23 to 25% of carbohydrate in the form of amylose. The glucose and insulin responses were measured over a period of 180 min. Serum glucose response to high amylose rice was significantly lower at 30 min, and dropped more gradually by 180 min than with 0% amylose rice. In addition, the high amylose rice produced significantly lower insulin levels at 30 and 60 min, as well as lower integrated secretion over the 3-h test. Thus, our results suggest the presence of a factor in high-amylose rice which delays digestion and/or absorption of carbohydrate. Since fiber content and surface area of the test rices were identical, other factors must underlie these observed differences. These include differential enzymatic hydrolysis of amylose and amylopectin and the presence of lipid-starch complexes in the amylose-containing rice.

Adult↗
PubMed1984

Antegrade translumbar aortography.

A new catheter-needle combination is described for use in translumbar aortography using a T-12 approach. The catheter has a 90 degree angle 1.5 cm from the tip that allows ready antegrade or retrograde catheterization of the abdominal and thoracic aorta. Injections of contrast material are performed with a tip occluder in place.

Aortography↗