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Biomedical subjects

L Klein

Publications and source records attributed to L Klein.

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

Variation of resorption rates in vivo of various bones in immature rats.

The 3H-tetracycline method of measuring bone resorption in vivo was applied to the comparison of various whole bones in rats of two different ages. The rat was chosen because it grows via modelling processes and contains little, if any, cortical remodelling except for a small amount of trabecular remodelling. It was found that resorption rates in vivo are high and similar in almost all of the 18 bones measured between birth and 2 weeks of age. However, in weanling rats studied at 4-6 weeks of age, resorption rates in the skull and in the long bones had decreased significantly while remaining high in the vertebrae, scapula, sternum and pelvis. Bones of neonatal rats were quite alike in their rates of bone resorption, but the bones of the weanlings manifested significant heterogeneity in their rates. It is known that anatomic heterogeneity of metabolic turnover of various bones characterizes the mature state in humans and dogs as well. The present data are unique in that they reflect absolute resorption rates in vivo uncomplicated by the extensive re-utilization of calcium inherent in other isotopic or non-isotopic protocols.

Animals↗
PubMed1990

Decreasing rates of bone resorption in growing rats in vivo: comparison of different types of bones.

This study quantifies rates of bone resorption by measuring the kinetic loss of 3H-tetracycline in vivo from the five different types of whole bones in four ages of normal male rats: appendicular bone (femur), cephalic bone (calvarium), axial bones (sixth lumbar vertebrae and sternum), and pelvis. The skeletons of newborn (0-2 weeks), weanling (4-7 weeks), adolescence (10-14 weeks), and mature (15-23 weeks) of Sprague Dawley rats were multiply labeled with 3H-tetracycline. The radioactivity in whole calvaria, the 6th lumbar vertebra, sternum, pelvis and femur was quantified to calculate the time course of tetracycline loss. The isotopic half lives (t1/2) were different for each age group and each bone, but the rates of resorption were usually the highest in the newborn rats. In the youngest animals, the t1/2 for the femur, vertebrae, and sternum was 1.5 week, for the pelvis it was 2.0 week, and for the calvarium it was 2.5 week. In the oldest age group, t1/2 for the femur was 28 week, for the calvarium was 19 week, for the sternum and pelvis was 16.5 week, and for the vertebrae was 13 week. For cephalic bones and femur, the greatest decrement in the rate of resorption occurred in the first 7 weeks of life (-52% and -72%, respectively). The axial bones and pelvis maintained a uniformly high resorptive rate until 7 weeks of age, which waned sharply at adolescence (-70% to -78%). At maturity the resorptive rate of these bones was less than 16% of the rate in the newborn.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1990

Anesthetic complications in the horse.

The basis for management of all complications is early recognition, preparation, and a problem-solving approach. Some anesthetic complications, such as equipment malfunction and injuries from endotracheal intubation or misplaced drug injections, are common to all animals and can be prevented almost entirely by careful management. Other problems, such as pulmonary dysfunction and cardiovascular depression, seem to occur more often in healthy horses than in healthy members of other domestic species. Postoperative myopathy-neuropathy, sometimes a devastating complication, seems to be peculiar to the horse, and its incidence has been linked to hypotensive inhalant anesthesia. Careful positioning and padding, monitoring of anesthetic depth, and treating of cardiovascular depression may prevent most cases of postanesthetic myopathy. Idiosyncratic drug reactions, such as MH, are entirely unpredictable and can be rapidly fatal unless recognized early and treated vigorously and specifically.

Anesthesia↗
PubMed1990

Antigenic requirements for stimulation and target cell recognition by immune and non-immune cytotoxic T lymphocytes.

The molecular requirements for recognition of antigen-modified cells by cytotoxic T lymphocyte precursors (CTLp) and their activated progeny, cytotoxic T lymphocytes (CTL), have been compared using haptenated stimulator and target cells. The antigen density requirements of T cell recognition by fluorescein-specific CTLp and CTL derived both from naive mice and from animals previously primed in vivo were determined. The cell surface hapten concentration required to stimulate CTLp cannot be distinguished from that required on target cells for lysis by their mature daughter CTL 5-7 days later. However, if the CTL (and their precursor CTLp) are derived from mice primed in vivo with hapten-conjugated cells, they require lower cell surface hapten densities for recognition than do the analogous T cell populations from naive animals. Thus, the maturation of CTLp into CTL during 5-7 days in vitro does not result in any functionally relevant change in the nature or density of antigen receptors on the surface of the T cell. This is in contrast to the apparent selection which occurs over longer time periods in vivo following priming.

Animals↗
PubMed1990

Molecular structure of frizzled, a Drosophila tissue polarity gene.

The function of the frizzled (fz) locus is required to coordinate the cytoskeletons of pupal epidermal cells so that a parallel array of cuticular hairs and bristles is produced. We report here the molecular cloning and characterization of the fz locus. The locus is very large. Mutations that inactivate the gene are spread over 100 kb of genomic DNA. The major mRNA product of the gene is a 4-kb RNA that is encoded by 5 exons spread over more than 90 kb of genomic DNA. Conceptual translation of this mRNA indicates that it encodes an integral membrane protein that is likely to contain both extracellular and cytoplasmic domains.

Amino Acid Sequence↗
PubMed1990

Visualization of multimodality cardiac imagery.

A large number of clinically important and medically difficult decisions in diagnostic radiology involve interpreting the information derived from multiple imaging modalities. This is especially true in the assessment of heart disease, wherein at least two types of image information are generally required prior to deciding on the course of action: structural information describing coronary vessel anatomy and functional information related to heart muscle physiology. This paper will present and discuss the methods and results associated with a research program aimed at quantifying and visualizing the unified anatomic and physiologic information obtained from these complementary imaging modalities. The discussions will emphasize the reconstruction, processing, and visualization of three-dimensional cardiovascular structure, including the procedures and results obtained from phantom and patient studies.

Computer Graphics↗
PubMed1990

Cyclosporin A and tissue antigen matching in bone transplantation. Fibular allografts studied in the dog.

We studied the mechanical, metabolic, and histologic properties of short-term nonvascularized cortical bone grafts in a canine fibular graft model. Sham operated nonvascularized autotransplanted and allotransplanted bones were compared. The allografts were performed between dog leukocyte antigen (DLA) class I and II matched; DLA class I and II mismatched; and cyclosporin A (CsA) treated, DLA class I and II mismatched animals. Cyclosporin was given for 1 month, and all the animals were followed for 3 months after surgery. Mechanical properties were investigated using standard torsional tests, metabolic kinetics were assessed using isotopic prelabeling techniques, and histomorphometric analysis of cross-sectional area properties and sequential fluorochrome labels were performed. Autografts were mechanically stronger and stiffer than all the types of allograft. CsA-treated, DLA-mismatched allografts performed better than matched allografts. These in turn were stronger than non-CsA-treated, mismatched allografts, which underwent nearly complete resorption. These relationships were preserved in the metabolic and histologic analyses. In this short-term animal study, although DLA matching resulted in a slight improvement in graft outcome, mismatched grafts in dogs receiving a short course of cyclosporin A fared even better.

Animals↗
PubMed1990

Age-related inequality between rates of formation and resorption in various whole bones of rats.

Variations in rates of bone turnover, consisting of bone formation and bone resorption, were characterized as a function of age and types of bone. Bone formation and bone resorption were quantified and compared in four ages of growing male rats (newborn, 0-2 weeks; weaning, 4-7 weeks; adolescence, 10-14 weeks; and mature, 15-23 weeks) for cephalic bone (calvaria), appendicular bone (femur), axial bones (sixth lumbar vertebrae and sternum), and the pelvis. In all four ages studied, inequality between the rates of bone formation and resorption existed in all bones, and the magnitude of the differences in metabolic imbalance turnover was age and bone type dependent. Formation was consistently higher than resorption in all five bones throughout the entire experimental periods. The ratio of resorption to formation was the lowest at birth (under 0.10:1) for all five bones and then increased. The most rapid bone growth in terms of bone calcium mass occurred at the weaning age (the net gain of calcium per bone per day was the highest) for all bones except the lumbar vertebrae, which occurred at adolescence. The magnitude of the inequality in the rates of bone formation and resorption was greatest in the newborn and diminished with age towards equality. At maturity, the ratio of resorption to formation was under 0.50:1 in the most dense or calcified bones such as the calvarium (0.40:1) and femur (0.49:1), and over 0.50:1 in the relatively thin cortex and well-trabeculated axial bones (0.60:1 in lumbar vertebrae and 0.75:1 in the sternum) and the pelvis (0.91:1). Additionally, large bones (calvaria, long bones, and pelvis) seemed to play an important role in regulating calcium homeostasis starting form the weanling age, since the amount of calcium released from each whole bone per day was high in these bones due to their large mass.

Aging↗
PubMed1990

[Approach of relations to trauma patients in intensive care units].

Because of medical sciences and techniques progresses, Intensive Care Units receive more and more difficult patients. Treatment and care have to respect people human dignity. Person contains body and mind, which are inseparable, as relation and care are. For us, nurses, patients global care have to harmonize technical quality of care and human dimension.

France↗
PubMed1990

[Personal experience with the treatment of burns].

Initial experience and results in treating burns are reported as obtained by plastic surgery service of Regional National Health Center. Starting from 1. 9. 1985 to 31. 12. 1987 a total of 48 burned cases was managed, from them 6 (12.5%) died. Authors proceeded by early necrectomy in indicated cases. As transitory skin coverings, the living xenografts appeared to be the most successful. The role of skin banking is emphasized in treating burns. The mentioned service provides a systematic complexive and continual care of cases with burns.

Adolescent↗
PubMed1990

Use of dura mater allografts in operations of abdominal wall hernias.

Treatment of large and recurrent abdominal wall hernias represents a rather complicated problem in surgical tactics and technique. In an effort to overcome the shortage of autogeneic material for strengthening the abdominal wall it is possible to substitute the defect by different synthetic or biological materials. Our experience with the use of freeze-dried dura mater is dealt with. The total of 18 allogeneic grafts were used in 11 patients with ventral hernias. The therapeutic procedure and clinical results are reported. Minor complications have developed in 2 patients, but they did not influence the good results of surgical treatment.

Aged↗
PubMed1990

Biological and physical properties of autogenous vascularized fibular grafts in dogs.

The biological and biomechanical properties of normal fibulae, fibulae that had had a sham operation, and both vascularized and non-vascularized autogenous grafts were studied in dogs at three months after the operation. The study was designed to quantify and correlate changes in these properties in orthotopic, stably fixed, weight-bearing grafts and to provide a baseline for additional studies of allografts. The grafts were eight centimeters long and internally fixed. The mechanical properties of the grafts were studied by torsional testing. Metabolic turnover of the grafts was evaluated by preoperative labeling of the dogs with 3H-tetracycline for resorption of bone mineral and with 3H-proline for turnover of collagen. Cortical bone area and porosity were measured. Postoperative formation of bone was evaluated by sequential labeling with fluorochrome. The vascularized grafts resembled the fibulae that had had a sham operation and those that had not had an operation with regard to the total number of osteons and the remodeling process, as measured both morphometrically and metabolically. The vascularized grafts were stronger and stiffer than the non-vascularized grafts and were not different from the bones that had had a sham operation. In contrast, the non-vascularized grafts were smaller, weaker, less stiff, and more porotic, had fewer osteons, and demonstrated increased turnover and resorption compared with the vascularized grafts, the bones that had had a sham operation, and the bones that had not been operated on.

Animals↗
PubMed1990

Routine human immunodeficiency virus infection screening of women requesting induced first-trimester abortion in an inner-city population.

Infection with the human immunodeficiency virus (HIV) among reproductive-age women occurs disproportionately among inner-city minority populations. These women are at risk because of intravenous drug abuse and heterosexual transmission from partners infected through drug abuse. From July 1, 1988 to December 31, 1988, we conducted routine voluntary screening for HIV antibody among 923 women who requested induced first-trimester abortion at Grady Memorial Hospital. Eight (8.7 per 1000) women were seropositive on repeat enzyme-linked immunosorbent assay and Western blot testing. Two infected women had had heterosexual contact with a person at risk for HIV infection, two others reported "crack" cocaine use, and four acknowledged no risk factors. Thirteen percent of seronegative women reported risk factors for HIV infection. Nearly all women consented to HIV testing, and most completed the risk-behavior questionnaire. These data suggest that women seeking first-trimester abortion at our hospital are at risk for HIV infection.

Abortion Applicants↗
PubMed1989

[Nontropical pyomyositis].

Pyomyositis of the pectoralis major was diagnosed in a 79-year-old man and Staphylococcus aureus was grown from pus drained from the infected muscle. Bacteremia and overwhelming sepsis accompanied the infection, and the patient died despite early diagnosis, combined chemotherapy and surgical drainage. The incidence of pyomyositis has been increasing lately in temperate climates. To our knowledge, this is the first report of nontropical pyomyositis in Israel.

Aged↗
PubMed1989

Prevention of ligament and meniscus atrophy by active joint motion in a non-weight-bearing model.

This study describes the effect of active joint motion on the maintenance of ligament and meniscus mass in a non-weight-bearing model of disuse. Denervation and fixation models of immobilization have shown that resorption of isotope and atrophy of mass occurred for hard tissue (bone) and soft tissues (ligament, tendon, or meniscus). A unilateral ankle disarticulation model of disuse that maintains active knee motion without weight bearing was studied for 8 weeks in dogs that were chronically prelabeled with three different isotopes. The effects of non-weight-bearing without denervation or fixation were analyzed for the resorption of isotopes, and net atrophy of bone mass (femur or tibia) and soft-tissue mass (collateral or cruciate ligaments, menisci). A large and similar loss of all three isotopes, as well as collagen and calcium mass occurred for whole femur and tibia; this indicated that mass loss was equivalent to bone resorption and suggests little replacement with new bone. No loss of isotope or mass per whole tissue occurred for the collateral and cruciate ligaments or menisci. The strength of the femur-anterior cruciate ligament-tibia complex was analyzed by a tensile failure test when a fast rate of deformation was applied; the results did not differ qualitatively or quantitatively between control and experimental limbs. The absence of weight bearing for 8 weeks resulted in marked bone atrophy without resorption or atrophy of soft tissues, or decrease of the mechanical strength for the femur-ligament-tibia complex.

Animals↗
PubMed1989

A pharmacokinetic model in the rat and rabbit of the direct measurement of mature bone resorption in vivo with [3H]tetracycline.

This report presents a pharmacokinetic model in the rat and rabbit of the direct quantification of mature bone resorption in vivo. This is based on a first-order reaction rate describing the release of [3H]tetracycline from bone. Compared with the previous method, the model has two new means of expressing bone resorption. First, resorption rate of bone is precisely represented by explicit parameters derived from the model. Second, resorption rate of the whole skeletal system is measured and demonstrated by means of plasma, renal, and bone kinetics of elimination of the isotope. These are represented by the model parameters, the elimination constant, and the half-life of [3H]tetracycline for plasma, urine, and bone. Four ages of normal Sprague Dawley rats and one age of New Zealand white rabbits of both sexes were prelabeled extensively with [3H]tetracycline in utero or during 10 to 84 d of age. Following 1-21 d after the end of prelabeling, the loss of the isotope from femur into plasma and urine was measured at weekly intervals to determine bone resorption of mineral in vivo. The elimination constants of the isotope per day in plasma were -0.148 in weaning rats (4-7 weeks), -0.071 in adolescent rats (10-14 weeks), and -0.025 in mature rats (15-23 weeks). The urinary elimination constants of the isotope per day were 74, 76, and 76% of those in plasma in weaning, adolescent, and mature rats, respectively. The half-lives of the isotope in the femur were 10 d in neonatal rats (0-2 weeks), 32 d in weaning rats, 63 d in adolescent rats, and 198 d in mature rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗