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Biomedical subjects

L Klein

Publications and source records attributed to L Klein.

At least 127 records · Page 7Linked to original sources
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↗
PubMed1989

Reversal of left ventricular dilatation, hypertrophy, and dysfunction by valve replacement in aortic regurgitation.

Although aortic valve replacement for aortic regurgitation relieves left ventricular volume overload, ventricular geometry does not consistently normalize. To assess the extent, determinants, and functional consequences of reversal of left ventricular dilatation and hypertrophy, 38 patients with severe aortic regurgitation were studied pre- and postoperatively by serial echocardiography and radionuclide cineangiography. Left ventricular end-diastolic dimension normalized in 58% of patients by 9 +/- 6 months postoperatively, at which time 50% of patients had normalized mass; cumulative normalization rose to 66% for end-diastolic dimension and 68% for left ventricular mass during further follow-up. All patients who had normalized end-diastolic dimension also had normal postoperative ejection fractions (mean 61 +/- 8%). In contrast, patients in whom the left ventricle remained dilated had a 42% prevalence of subnormal postoperative left ventricular ejection fraction. Preoperative left ventricular end-systolic dimension less than or equal to 55 mm identified 86% of patients in whom end-diastolic dimension normalized, whereas end-systolic dimension exceeded 55 mm in 81% of those with persistent dilatation; other proposed preoperative predictors of operative outcome correctly identified lower proportions (from 59% to 71%) of patients in whom left ventricular size did or did not normalize. In conclusion, aortic valve replacement resulted in normalized left ventricular chamber size and mass in two thirds of the patients selected for operation by current criteria; favorable geometric outcome is associated with persistence or recovery of normal left ventricular function.

Aortic Valve↗
PubMed1989

Seroprevalence of human immunodeficiency virus infection in a prenatal population at high risk for HIV infection.

To determine the seroprevalence of human immunodeficiency virus infection in prenatal patients at high risk for HIV infection we tested 513 women from December 1985 through July 1987 at an inner-city hospital in Atlanta, Georgia. Demographic and HIV risk information was collected from all seropositive women. Twenty-nine (6%) of the 513 women tested were positive for HIV on enzyme-linked immunosorbent assay and Western blot analysis. Twenty-six (90%) of seropositive women gave a history of intravenous drug use. Two (7%) had sexual partners known to have AIDS or AIDS-related complex (ARC), and one (3%) was Haitian. Seropositive women were at remarkable risk for other sexually transmitted diseases. The majority of pregnancies ended in term births. This serosurvey defines an obstetric population with a high seroprevalence, and has stimulated us to institute routine voluntary antepartum screening for HIV.

Adolescent↗
PubMed1989

Vacuum fixation of corneal lenticules for refractive surgery.

Using the rotating lamellar keratome, a simplified method for nonfreeze shaping of corneal tissue was developed. A set of refractive molding forms was designed for a standardized lenticule diameter. The fixation of the lenticule was achieved by a system of suction holes. A mechanical fixation ring was not required, as the total shearing force exerted by the rotating blade is neutralized even by a low suction setting. Different surface properties (polished, matt, rough) were compared, showing an influence of the surface structure on friction and thus lenticule fixation. With our optimized molding form, the lenticule is safely retained at a suction of 2.5 m H2O.

Cornea↗
PubMed1989

Apparent motion: evidence of the influence of shape, slant, and size on the correspondence process.

Four stimulus elements configured as a notional diamond were flashed in pairs to elicit apparent motion. When the elements were identical (4 Zs), the direction of apparent motion was ambiguous. When the elements were pairs of different letters (Cs and Os, Es and Zs), letters of different sizes (Zs and zs), or oppositely oblique lines, the direction of apparent motion tended to be between identical elements. This was true, however, only for an initial, brief observation period. Subsequently, the direction of apparent motion tended to be determined by the direction of motion perceived at first, regardless of the character of the elements. This quickly established directional set (within 10 sec) largely swamped any tendency to resolve correspondence in terms of a feature of the stimulus. It appears to be based on spatial rather than retinal or egocentric coordinates.

Attention↗
PubMed1989

Routine antepartum human immunodeficiency virus infection screening in an inner-city population.

Human immunodeficiency virus (HIV) infection occurs disproportionately among inner-city minority women of reproductive age. Once pregnant, these women have a high risk of delivering infants with perinatally acquired infection. Identification and counseling of HIV-infected parturients may be an effective means of preventing perinatal HIV infection. Few data are available on the seroprevalence of HIV infection in the inner-city population or on the clinical and demographic determinants of risk. To better characterize HIV infection in inner-city parturients in Atlanta, we conducted routine antepartum screening for HIV antibody in 3472 women. Ten (2.8 per 1000) were seropositive on enzyme-linked immunosorbent assay (ELISA) and Western blot testing. Four women were seropositive on repeat ELISA but negative on Western blot. Four infected women had had heterosexual contact with a person at risk for HIV, three were intravenous drug users, one had possibly become infected via blood transfusion, and two had no apparent risk factors. Seven of the seropositive women had no self-identified risk factors and would not have been identified if screening had been performed using current Centers for Disease Control criteria. Ten percent of the women screened had self-identified risk factors for HIV infection and were seronegative. Ninety-six percent of women consented to HIV testing. These data suggest that inner-city parturients in Atlanta are at risk for HIV infection and that routine antepartum HIV screening can be performed provided the appropriate multidisciplinary team is in place for counseling and follow-up.

Acquired Immunodeficiency Syndrome↗