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Biomedical subjects

S Lichtman

Publications and source records attributed to S Lichtman.

At least 37 records · Page 2Linked to original sources
PubMed1990

Body composition of humans: comparison of two improved four-compartment models that differ in expense, technical complexity, and radiation exposure.

Multicompartment models are of growing importance in the study of body composition in humans. This study compares two improved four-compartment (water, protein, mineral, and fat) models that differ in expense, technological complexity, and radiation exposure. Primary data (from 31 subjects) for the first model were derived by dual-photon absorptiometry, 3H2O dilution, and hydrodensitometry and for the second model by delayed and prompt gamma neutron-activation analysis and 3H2O dilution. Estimates of fat, protein, and mineral from the first model were highly correlated with those from the second model (r = 0.98, 0.72, and 0.94, respectively; all p less than 0.001). The proportions of body weight represented by water, protein, mineral, and fat for the simpler first model (0.532, 0.155, 0.048, and 0.265) were similar to compartment fractions provided by the more complex and costly second model (0.532, 0.143, 0.046, and 0.279). Multicompartment body composition models can thus be developed from increasingly available techniques that compare favorably with similar results derived from limited-access instrumentation.

Absorptiometry, Photon↗
PubMed1990

Appendicular skeletal muscle mass: measurement by dual-photon absorptiometry.

Dual-photon absorptiometry (DPA) allows separation of body mass into bone mineral, fat, and fat-free soft tissue. This report evaluates the potential of DPA to isolate appendages of human subjects and to quantify extremity skeletal muscle mass (limb fat-free soft tissue). The method was evaluated in 34 healthy adults who underwent DPA study, anthropometry of the limbs, and estimation of whole-body skeletal muscle by models based on total body potassium (TBK) and nitrogen (TBN) and on fat-free body mass (FFM). DPA appendicular skeletal muscle (22.0 +/- 3.1 kg, mean +/- SD) represented 38.7% of FFM, with similar proportions in males and females. There were strong correlations (all p less than 0.001) between limb muscle mass estimated by DPA and anthropometric limb muscle areas (r = 0.82-0.92), TBK (r = 0.94), and total-body muscle mass based on TBK-FFM (r = 0.82) and TBK-TBN (r = 0.82) models. Appendicular skeletal muscle mass estimated by DPA is thus a potentially practical and accurate method of quantifying human skeletal muscle mass in vivo.

Absorptiometry, Photon↗
PubMed1990

New approaches to body composition research: a reexamination of two-compartment model assumptions.

The field of human body composition research by necessity is based upon assumptions related to tissue chemical content. The 2-compartment model, which requires only 1 measurement in addition to body weight, is the cornerstone of current research in this field. Yet the assumptions upon which 2-compartment models are based were developed on a limited scale and their validity under specified conditions is questionable. Recent developments now allow quantification of previously unmeasured somatic constituents. The capacity to extend our models to 4 or more components is now at hand. Not only will this allow us to vastly expand our validation of two 2-compartment approaches, but our ability to explore new and important physiological questions is within reach.

Adipose Tissue↗
PubMed1990

A successful partnership.

Physicians considering partnership agreements should follow a well-designed plan for recruitment, interviewing, and negotiation. This process can ensure future success of the partnership, and prevent legal difficulties.

Partnership Practice↗
PubMed1990

Stereologic analysis of monocytes and their subcellular organelles in patients with acute monocytic and myelomonocytic leukemia.

The stereologic characteristics of monocytes from patients with acute nonlymphocytic leukemia containing a monocytic component (FAB M4 and M5), and the monocytes from normal individuals were determined by morphometric analysis. The cells studied were monocytic cells beyond the promonocyte stage of development, as defined by ultrastructural criteria. Parameters evaluated included cell and nuclear volumes and surface areas, mitochondrial and myeloperoxidase (MPO)-positive secretory granule volume and numerical density as well as volume and number of the organelles/cell. Peripheral blood and bone marrow monocytes of leukemic patients could not be distinguished by their cell or organelle stereologic characteristics. Monocytes from patients with both M4 and M5 acute leukemia had relatively large cell and nuclear volumes. Mitochondrial volume density and volume/cell were also high in monocytes from leukemic patients (M4; 21 microns 3/cell, M5 20 microns 3/cell) as compared with monocytes from normal individuals (8.5 microns 3/cell). On the other hand, MPO-positive secretory granule stereologic parameters in monocytes from leukemic patients were indistinguishable from those of normal individuals. A small number (3 of 18) patients showed very low monocyte MPO-positive granule volume densities. There was a slight positive correlation between MPO-positive granule volume density and patient survival time. No relationship between mitochondrial characteristics and survival was noted.

Adult↗
PubMed1989

Body composition in elderly subjects: a critical appraisal of clinical methodology.

Body composition measurements are integral to nutritional assessment of elderly subjects. The validity of methods available for partitioning body weight into its tissue or chemical subfractions in the geriatric population is of primary importance. Until recently verifying the accuracy of body composition techniques in vivo was limited by prevailing technology. New advances such as neutron activation analysis, neutron inelastic scattering, and dual photon absorptiometry now promise to overcome these earlier limitations. With these new tools investigators can now examine critical underlying assumptions related to body composition assessment in elderly subjects. This review highlights the need and opportunities for future research in this area.

Aged↗
PubMed1989

Chemical determination of human body density in vivo: relevance to hydrodensitometry.

A chemical approach to establishing human body density in vivo was developed by combining recently developed noninvasive methods. Four compartments were measured: protein (P; prompt-gamma neutron activation), water (A; 3H2O dilution), mineral (M; dual-photon absorptiometry and delayed-gamma neutron activation), and fat (F; dual-photon absorptiometry). By this model body weight is equal to P + A + M + F. This approach was applied to 13 healthy adults (8 females and 5 males). The four compartments accounted for greater than 97% actual body weight. Calculated density based upon composition agreed within 0.6 +/- 0.4% (mean +/- SD) with density (D) measured by hydrodensitometry [calculated D (g/cc) = 0.86 measured D +0.15; r = 0.94, p less than 0.001]. The average calculated lean (P + A + M) density of 1.096 +/- 0.007 g/cc agreed closely with three classic human cadaver studies (1.100 g/cc). This multicompartment approach provides a new opportunity to estimate human body density in vivo and to refine body composition methods based upon an assumed but inadequately validated constant lean density.

Absorptiometry, Photon↗
PubMed1988

Monosomy 5 in acute megakaryoblastic leukemia. Report of two cases.

Two cases of acute megakaryoblastic leukemia are reported. The diagnoses were confirmed by clinical, morphologic, and cytochemical analysis. Karyotypic analysis demonstrated monosomy 5 in both patients, providing further evidence that acute megakaryoblastic leukemia is a subset of the acute nonlymphocytic leukemias and may be etiologically related to the myelodysplastic syndromes.

Adult↗
PubMed1988

Effect of tetrahydrouridine on the clinical pharmacology of 1-beta-D-arabinofuranosylcytosine when both drugs are coinfused over three hours.

When 1-beta-D-arabinofuranosylcytosine (ara-C), 25 mg/m2, is infused over 3 h together with tetrahydrouridine (THU) at 10 to 350 mg/m2 to heavily pretreated patients with solid tumors, Michaelis-Menten type kinetic values are observed with leveling off of delta area under the curve, delta ara-C levels at 3 h, and delta total body clearance after 150 mg/m2 of THU. When the ara-C dose was increased to 50, 75, and 100 mg/m2 coinfusion of 250 or 350 mg/m2 of THU significantly increased plasma ara-C at peak and area under the curve. In contrast, total body clearance and volume of distribution decreased significantly. At 100 mg/m2 of ara-C coinfused with high doses of THU, i.e., at 350 mg/m2, the pharmacokinetics of plasma ara-C was changed from a biphasic decay of plasma ara-C at peaks (control) to a curve similar or identical to a monophasic curve, indicating that THU not only inhibits deamination but also changes the distribution of ara-C. This combination provides plasma ara-C levels (greater than or equal to 10 microM) comparable to high dose ara-C at 1 g/m2. Such plasma ara-C levels are considered to be sufficient for saturation of the kinases catalyzing the production of 1-beta-D-arabinofuranosylcytosine 5'-triphosphate. This reduced ara-C dose necessary to achieve saturation of kinases also reduces plasma 1-beta-D-arabinofuranosyluracil levels substantially. Toxicity of this combination was predominantly confined to bone marrow and gastrointestinal toxicity.

Adult↗
PubMed1987

Neoplastic complications of HTLV-III infection. Lymphomas and solid tumors.

Neoplastic disease arose in 29 of 200 patients infected with human T lymphotropic virus type III (HTLV-III) seen at a suburban hospital. Seventeen patients had Kaposi's sarcoma, one of whom also had colon carcinoma. Nine patients had lymphoproliferative disorders (seven lymphomas, one T suppressor cell chronic lymphocytic leukemia, and one multiple myeloma), including three with concomitant Kaposi's sarcoma and one with colon cancer. One other patient had colon cancer, one had a seminoma, and one had pancreatic cancer. Kaposi's sarcoma as a complication of AIDS occurred mainly in homosexuals (17 of 42 homosexuals, one of 17 drug abusers, one of five heterosexually promiscuous patients, and one of six patients who had previously received transfusions). The high-grade lymphomas did not show a predilection for any particular AIDS risk group. Three of four solid tumors arose in elderly AIDS patients. Twenty-five of 75 patients with CDC-defined AIDS had a neoplastic disorder (26 are still alive and may yet demonstrate malignancy). Few other diseases of man have been associated with as high an incidence of neoplastic transformation as occurs with HTLV-III infection.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Morbidity after percutaneous liver biopsy.

The safety of percutaneous liver biopsy with a 1.2 mm Menghini needle in infants aged one year or less was investigated. One hundred and eighty four procedures performed from 1975 to 1985 were reviewed. There were no deaths or major complications within 48 hours associated with the procedure. In five instances specific complications occurred: a drop in haemoglobin concentration (three), transient hypotension (one), and haematoma at the biopsy site (one). The result of liver biopsy was diagnostic in 83% of cases, compatible with unspecified metabolic disease in 8%, and normal or not diagnostic in 9%. This study suggests that percutaneous liver biopsy can be performed with relative safety in small infants if coagulation is normal and there are no major contraindications, and the results yield important diagnostic information which cannot be obtained using less invasive procedures.

Biopsy, Needle↗
PubMed1986

Production of secretory immunoglobulin A in rat self-filling blind loops. Local secretory immunoglobulin A immune response to luminal bacterial flora.

The immunoglobulin A (IgA) response to small intestinal bacteria was studied in rats with self-filling blind loops (SFBLs), surgically constructed in continuity with the intestine or at the end of a Roux-en-Y loop (RY-SFBL) so as to avoid filling with chyme. Total bile salt in the RY-SFBL lumen was much lower (4.35 +/- 0.8 mumol) than in the SFBL lumen (116 +/- 15 mumol), but other parameters, such as the number of anaerobic bacteria and disaccharidase activities were similar. Within 1 wk of establishing the blind loops, they had accumulated at least 14 times as much IgA as found in the normal jejunum. Luminal IgA per milligram mucosal protein was almost as high in the RY-SFBL as in the SFBL, indicating that a significant proportion of the IgA must be nonbiliary and probably mucosal in origin. Oral treatment with lincomycin significantly reduced luminal IgA accumulation in the RY-SFBL. Column chromatography and enzyme-linked immunosorbent assay (ELISA), which employed antirat secretory component antibody, established that the majority of the luminal IgA was nonmonomeric and complexed with secretory component. Centrifugation of luminal contents to separate soluble and particulate bound IgA showed that the RY-SFBL contained a higher proportion of precipitable IgA than either the SFBL or lincomycin-treated RY-SFBL. Immunoglobulin A eluted from the precipitates by KSCN was bound to a greater extent by bacterial sonicates than IgA in the supernatant. For either precipitate or supernatant IgA, the greatest binding was observed when the IgA was obtained from the RY-SFBL. These observations indicate that rat intestinal mucosa rapidly responds to bacterial overgrowth by secreting secretory immunoglobulin A (sIgA) with specificity for luminal bacterial antigens. As the sIgA present within the SFBL is to a certain extent derived from bile, the lower proportion of SFBL sIgA bound by bacterial antigens than of RY-SFBL sIgA suggests that biliary sIgA is less specific for local antigens than the sIgA that is secreted by the local mucosa.

Animals↗
PubMed1986

Chronic intussusception due to antral myoepithelioma.

Intussusception was seen on abdominal sonography and computed tomography in a 15-year-old boy who presented with a 6-week history of weight loss, vomiting, abdominal pain, abdominal mass, and hyperamylasemia. Laparotomy revealed a chronic gastroduodenal intussusception, the lead point of which was an antral myoepithelioma, a rare entity in this age group.

Adolescent↗
PubMed1986

Eosinophilic gastroenteritis presenting in an adolescent with isolated colonic involvement.

Eosinophilic gastroenteritis most commonly involves the stomach and proximal small intestine with eosinophilic inflammation of either the mucosa, submucosa or serosa. The patient reported here had isolated eosinophilic colitis. The initial presentation with iron deficiency anaemia owing to occult gastrointestinal blood loss emphasises the need to evaluate the entire gastrointestinal tract in patients with eosinophilic gastroenteritis.

Adolescent↗
PubMed1984

Temporomandibular joint repositioning and exercise performance: a double-blind study.

In the present study, the effects of temporomandibular joint (TMJ) repositioning by use of an acrylic appliance on maximum and submaximum physiologic and performance measures were evaluated in seven male and four female volunteers with documented TMJ malalignment. In an attempt to remove design inadequacies of previous research in this area, a double-blind strategy was utilized. Subjects were randomly assigned to each of four conditions: 1) normal, without a bite splint, 2) with a placebo splint with no occlusal contact so as to maintain normal jaw position, 3) with a splint that optimized jaw position, and 4) with a splint that magnified the subjects normal degree of malocclusion. Measurements were taken of visual reaction time and movement time, muscular strength of the grip, elbow flexors, and leg extensors, submaximal and maximal oxygen uptake, perceived exertion, anaerobic power output, and all-out working capacity in both arm and leg exercise on a cycle ergometer. Analysis of variance for repeated measures indicated that in no instance were the differences in mean scores on physiologic and performance measures with TMJ repositioning or placebo statistically significant when compared with the normal condition. This was the case for the group as a whole or when the five subjects with the greatest TMJ dysfunction were analyzed separately. These findings strongly support the contention that the beneficial effects of short-term TMJ repositioning on exercise performance noted in previous reports may be the result of inadequacies in research design and evaluation rather than the true effects of the bite splint.

Adolescent↗