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Biomedical subjects

A Kramer

Publications and source records attributed to A Kramer.

At least 145 records · Page 8Linked to original sources
PubMed1994

Role of protease inhibition in myocardial preservation following ischemia and reperfusion.

Aprotinin, a naturally occurring protease inhibitor, in concentrations of 10(6) KIU/L was found to have no effect on myocardial performance in normally perfused isolated rat hearts, before ischemia. Given during the preischemic period, the drug had a significant protective effect on the reperfused hearts, following cardioplegic ischemia: better contractility upon reperfusion (p < 0.011), faster decline of the ischemic contracture, higher coronary flow (p < 0.025), lower AV-difference (p < 0.05), and lower CPK levels (p < 0.01).

Animals↗
PubMed1994

[Effect of an alimentary thiocyanate supplement on the hide characteristics of mink (Mustela vision)].

In farm minks the following effects were achieved by additional feeding of KSCN (0,9-2,6 mg SCN-/kg body weight) equivalent to twice til triple the usual SCN- intake (0,2-0,9 mg SCN-/kg body weight) during the 3. to 7. month of life: improvement of the coat structure and of length, density, and elasticity of the guard hairs, additionally to increase of body weight and length.

Animal Feed↗
PubMed1993

Human taxonomic diversity in the pleistocene: does Homo erectus represent multiple hominid species?

Recently, nomina such as "Homo heidelbergensis" and "H. ergaster" have been resurrected to refer to fossil hominids that are perceived to be specifically distinct from Homo sapiens and Homo erectus. This results in a later human fossil record that is nearly as speciose as that documenting the earlier history of the family Hominidae. However, it is agreed that there remains only one extant hominid species: H. sapiens. Has human taxonomic diversity been significantly pruned over the last few hundred millennia, or have the number of taxa been seriously overestimated? To answer this question, the following null hypothesis is tested: polytypism was established relatively early and the species H. erectus can accommodate all spatio-temporal variation from ca. 1.7 to 0.5 Ma. A disproof of this hypothesis would suggest that modern human polytypism is a very recent phenomenon and that speciation throughout the course of human evolution was the norm and not the exception. Cranial variation in a taxonomically mixed sample of fossil hominids, and in a modern human sample, is analyzed with regard to the variation present in the fossils attributed to H. erectus. The data are examined using both univariate (coefficient of variation) and multivariate (determinant) analyses. Employing randomization methodology to offset the small size and non-normal distribution of the fossil samples, the CV and determinant results reveal a pattern and degree of variation in H. erectus that most closely approximates that of the single species H. sapiens. It is therefore concluded that the null hypothesis cannot be rejected.

Analysis of Variance↗
PubMed1993

[Thiocyanate blood levels in roe deer, red deer, fallow deer and wild boar].

The following serum levels of thiocyanate (SCN-) were found in game: roe 6.6 +/- 4 mg/l, red deer 5.5 +/- 3.2 mg/l, fallow-deer 5.1 +/- 2.8 mg/l, and wild boar 4.8 +/- 4.5 mg/l (variation 0.6-32.6 mg SCN-/l). These levels are distinctly higher than in domestic animals under stall-feeding with exception of mast calves which were fed milk-substitutes. The SCN- serum level of calves, sheep and horses reach at pasturing nearly the level of game. The higher SCN- serum level of cloven-hoof game resp. by pasturing of domestic animals is caused by higher alimentary SCN- intake.

Animals↗
PubMed1992

Rebound of plasma vancomycin levels after haemodialysis with highly permeable membranes.

Vancomycin is usually given only once a week to haemodialysis (HD) patients. If highly permeable dialysis membranes are used, however, high clearance values have been reported, so the aim of the study was to determine whether high clearance of vancomycin resulted in sufficient drug elimination to induce subtherapeutic plasma levels after one week. In 18 chronic HD patients, treated with polysulfone dialyzers (1.2 m2), the pharmacokinetics of vancomycin were studied after administration of 1 g. Concentrations were determined by fluorescence polarisation immunoassay. At a blood flow of 219 ml.min-1, HD clearance of vancomycin was 62.3 ml.min-1. Immediately after dialysis plasma concentrations were 38% lower than predialysis levels. However, marked rebound in the vancomycin level was observed 5 h later, resulting in plasma levels only 16% lower than prior to dialysis. 3 HD treatments in 1 week removed about one third of the initial dose. After one week 15 of 18 patients still had a therapeutic plasma level (greater than 4 micrograms.ml-1). In conclusion, polysulfone membranes show high clearance of vancomycin. However, transfer of drug from blood to dialysate appears to be faster than from tissues to blood. Because of a marked rebound in plasma level after treatment, therapeutic drug concentrations will still be present in most patients after one week.

Female↗
PubMed1992

Risk factors for systemic embolism in patients with paroxysmal atrial fibrillation.

The purpose of this study was to define the risk factors for systemic embolism in patients with recently diagnosed paroxysmal atrial fibrillation. We therefore studied 63 consecutive patients with symptomatic nonvalvular paroxysmal atrial fibrillation and performed a clinical and noninvasive cardiac, peripheral vascular, and neurologic evaluation that included two-dimensional echocardiography, 24-hour Holter monitoring, and computed tomographic brain scan. Patients with predisposing clinical conditions for systemic embolism (valvular heart or coronary artery disease) or paroxysmal atrial fibrillation (sick sinus disease, preexcitation, or thyroid dysfunction) were excluded. At entry 34 patients had idiopathic paroxysmal atrial fibrillation and 29 had hypertension. Fourteen patients had a recent systemic embolic complication: nine had a recent occlusive nonlacunar cerebrovascular accident, two had transient ischemic attacks, and three had peripheral systemic emboli that required surgery. In addition, five patients had evidence of old cerebrovascular accident on the computed tomographic scan (group 1). Forty-four patients had no systemic embolism (group 2). Results of univariate analysis showed that patients in group 1 were older (72 +/- 9 vs 63 +/- 13 years, p less than 0.05), had a higher incidence of hypertension (70% vs 35%, p less than 0.01), and had an increased left atrial diameter (4.1 +/- 0.7 vs 3.6 +/- 0.5 cm, p less than 0.05). Multiple stepwise logistic regression analysis showed that a history of hypertension and left atrial enlargement on two-dimensional echocardiography were significant independent risk factors for systemic embolism in patients with symptomatic nonvalvular paroxysmal atrial fibrillation.

Aged↗
PubMed1992

Human immunodeficiency virus infection due to clotting factor concentrates: results of the Seroconversion Surveillance Project.

From 1987 to the present, the Seroconversion Surveillance Project has provided the means by which to monitor the risk of transmission of human immunodeficiency virus (HIV) by clotting factor concentrates. One hundred thirty-one hemophilia treatment centers in the United States are contacted regularly, and data on HIV testing of patients are collected. To date, 4366 (46.0%) of 9496 patients have been reported to be seropositive, and 37 new seroconversions have been identified. Nine of these have met the Centers for Disease Control criteria for seroconversion while the patient was taking factor concentrate. None of the nine seroconversions were due to concentrates that had been treated to inactivate viruses and made from plasma that had been tested for HIV antibody. These results indicate that there is a high prevalence of seropositivity in affected patient groups, but that the risk of HIV infection from currently available clotting factor concentrates is extremely low.

Blood Coagulation Disorders↗
PubMed1991

Modern human origins in Australasia: replacement or evolution?

The controversies surrounding the origins of modern humans have spawned two competing hypotheses, namely Replacement and Multiregional Evolution. The first suggests that modern Homo sapiens evolved first in Africa, as late as 140 ka, and subsequently inhabited the balance of the Old World. Conversely, the second hypothesis posits that modern humans evolved principally from local populations of archaic hominids indigenous to the major regions of the Old World. The hominid mandibular remains (ca. 1 Ma) from Sangiran, central Java, Indonesia, were studied in order to test these hypotheses. Non-metric comparisons were performed between these fossils and aboriginal H. sapiens from Africa and Australia. The Replacement model would be supported by a unique Afro-Australian grouping while Multiregional Evolution would be suggested by a Sangiran-Australasian group which would exclude the modern Africans. These data support the Multiregional Evolution hypothesis in that a plurality (eight) of the seventeen non-metric features link Sangiran to modern Australians, while only three exclusively group the humans from Africa and Australia. These results are suggestive of morphological continuity, which implies the presence of a genetic continuum in Australasia dating back at least one million years.

Animals↗
PubMed1991

Geriatric evaluation and management: current status and future research directions.

In the last decade the concept of geriatric evaluation and management (GEM) has been widely discussed in the literature. Studies of GEM have occurred primarily in three settings: inpatient units, outpatient clinics, and specialized types of home care. We have reviewed the literature, focusing on randomized trials, to determine the strength of the evidence for the efficacy of these interventions. Two single-site randomized controlled trials of inpatient GEM units have been conducted and indicate that such units that provide care to targeted disabled older patients probably have a favorable impact on subsequent physical function, rates of institutionalization, and mortality. Two randomized trials of inpatient GEM consultation teams have been conducted. The trial that did not target high-risk individuals showed no benefit while the trial that did target an at-risk group showed that those receiving the service had improvements in mental status and short-term mortality. The results of randomized trials of outpatient GEM clinics to date have been unimpressive. Two trials of in-home GEM by a trained observer tended to show that the service resulted in a reduction in mortality. To date randomized trials of GEM have been very heterogeneous in terms of the type of assessment and subsequent care, the site in which services are delivered, and the manner in which patients are selected for the studies. This limits the ability to compare and extrapolate across studies. In the future there is a need to better clarify the selection of study participants, the exact structure of the assessment intervention provided, and the elements of successful interventions that may be most critical to insuring a good outcome.

Aged↗
PubMed1991

Working group recommendations: methods for geriatric evaluation and management research.

Methodological issues relating to multi-site studies of inpatient geriatric evaluation and management units were the focus of this working group's deliberations. The group favored a randomized clinical trial in which the inpatient geriatric evaluation and management unit was coupled with outpatient geriatric care. Inclusion of a broad spectrum of patients stratified according to risk for poor hospital outcomes was proposed in order to obtain information on the types of patients that would be most likely to benefit. The need for a detailed definition and description of care in the unit and of "usual care" was emphasized. Serious concerns were raised about including both VA medical centers and private hospitals in the same trial due to differences in the implementation of such a program. Furthermore, fears of contamination of the control group suggested that hospitals could be randomized either to provide usual care or have a GEM unit. However, this strategy would necessitate that hospitals that have already developed inpatient GEM units would be excluded from the trial and could be costly because of the number of hospitals that would be required.

Geriatric Assessment↗
PubMed1991

Research strategies for geriatric evaluation and management: conference summary and recommendations.

In this paper, we present the consensus statement from a national conference on research priorities and methodologies for studying geriatric evaluation and management (GEM) programs. These conclusions, discussion points, and recommendations resulted from discussions of plenary papers, working group deliberations, and a final session in which findings were synthesized by the conference co-chairmen and presented to conference participants for final review. Major conclusions included: (1) The importance of linking geriatric evaluation with care management in future studies; (2) The need for multi-center trials of inpatient units to establish efficacy; (3) The importance of studying criteria for targeting GEM care on patients who are most likely to benefit; (4) The need for further developmental studies of outpatient GEM clinics; (5) The importance of assessing a range of outcomes including mortality, patient function, satisfaction, caregiver burden, and cost; and (6) The need to define more carefully the nature of the intervention that is being studied to aid in comparing and extrapolating findings. The following research priorities for GEMS were formulated based on the conference: (1) Within the VA health care system, a multi-site randomized trial of inpatient GEM units should be initiated; (2) Multi-site studies of inpatient GEM units and consultation teams linked to outpatient care should be initiated in non-VA settings; (3) Studies should identify the components of GEM that are most critical to outcome; (4) Studies should explore efficacy of GEM in settings that have not been well studied to date such as nursing homes; and (5) Studies are needed to test screening methods and targeting criteria for GEM in all settings.

Geriatric Assessment↗
PubMed1991

Cigarette smoking: a modifier of human immunodeficiency virus type 1 infection?

Two hundred and two homosexual men enrolled in a prospective cohort study of AIDS risk were assessed for differences in the occurrence and progression of human immunodeficiency virus type 1 (HIV-1) infection with respect to cigarette smoking. Among subjects who were initially seronegative, smokers were more likely than nonsmokers to become HIV-1 seropositive (p = 0.03). After seroconversion, serum beta 2-microglobulin and CD4+ lymphocyte levels were elevated in cigarette smokers relative to nonsmokers (p = 0.02 for both comparisons), but both of these differences disappeared within 2 years. There was no detectable difference in the risk of AIDS or Pneumocystis carinii pneumonia with respect to smoking. Our data suggest that cigarette smoking may alter the immune response to HIV-1 infection, but it appears to have no marked effect on clinical outcome. They also suggest that cigarette smoking may be a surrogate marker for continued high-risk sexual behavior in homosexual men.

Adult↗
PubMed1991

[Popliteal aneurysm: results of the management of 33 lesions].

Popliteal aneurysm is a rather infrequent lesion which may cause severe ischemia and loss of the extremity. Between 1975 and 1990, 21 patients, all male with a mean age of 73 years, presented with popliteal aneurysm which was associated to aneurysm in other arteries in 62% and other medical problems in 95% of patients. 61% of patients had severe ischemia due to thrombosis or embolism. Surgery was performed for 29 lesions (10 as an emergency). Exclusion and bypass was performed in 26 (20 with saphenous vein and 6 with a prosthesis). Amputation due to irreversible ischemia was required in 3 patients. There was no mortality in this series and only 1 patient required later amputation. Permeability was estimated at 85% at 5 years of follow up, including all bypasses. We conclude that popliteal aneurysm should be diagnosed and electively operated with saphenous vein grafting.

Aged↗
PubMed1991

[Acute ischemia of the upper extremity caused by axillary contused trauma. Report of 3 cases].

Blunt trauma to the axillary artery is infrequently associated to unstable proximal humeral fractures or anterior dislocation of the shoulder. We report 3 patients who developed this complication. One of them had associated neurologic injury. All patients required a saphenous vein interposition graft and the patient with neurologic injury required surgical decompression of the brachial plexus. The results of arterial repair were excellent. The patient with neurologic injury recovered significantly after decompression of the plexus, since he had not partial or complete transection of the plexus which is usually a permanent lesion. Our observations support that patients with axillary lesion associated with neurologic deficits should undergo prompt exploratory surgery.

Acute Disease↗
PubMed1990

[Detection of antibodies against Brucella in the aqueous humor using ELISA].

In aqueous bulbi of experimentally against Brucella abortus immunized guinea pigs and rabbits specific antibodies could be detected by ELISA-tests. This first demonstration of brucella antibodies in the aqueous shows that aqueous can be used for serological examinations. For practical use more investigations in experimental animals are necessary, e.g. on kinetics of orbital antibodies absence of interfering factors and biomechanics of proteins in aqueous.

Animals↗
PubMed1990

[24-hour blood pressure measurement in normal pregnancy in hypertensive pregnant patients].

Noninvasive 24-hour ambulatory blood pressure monitoring was performed in 17 normotensive and 19 preeclamptic pregnant women. The normotensive women showed a significant nightly decline in their systolic and diastolic blood pressure. In contrast, the preeclamptic women demonstrated either an attenuated circadian rhythm or no circadian rhythm at all. This result was even more pronounced in patients with severe hypertension, some of whom had a nocturnal increase in blood pressure in spite of being treated with antihypertensive drugs in an evening dose. The lack of nocturnal blood pressure decrease was also found 24 hours post partum. In summary, these results suggest that preeclamptic women are endangered by hypertensive emergencies mostly during the night. Therefore blood pressure controls should be extended into the night, and antihypertensive drugs should also be given in a sufficient evening dose.

Blood Pressure↗
PubMed1990

Pseudomembranous colitis: how useful is endoscopy?

Clostridium difficile colitis may be diagnosed either by endoscopy or by laboratory tests. To determine the role of endoscopy, we reviewed 59 cases of confirmed C. difficile colitis. In all patients, the etiology was confirmed by stool tests. Twenty-nine underwent lower gastrointestinal endoscopy. In 16 (55%) there was endoscopic confirmation of pseudomembranes while 4 (14%) had only nonspecific colitis. There was no apparent difference in the rate of detection of pseudomembranes between rigid sigmoidoscopy (57%), flexible sigmoidoscopy (50%), and colonoscopy (50%). Vancomycin and metronidazole were equally effective therapy but treatment with vancomycin cost more than 250 times that for metronidazole. There were no patients in whom the diagnosis was made by endoscopy alone. Endoscopy was costly and insensitive, while noninvasive stool tests were cheap and accurate. We conclude that endoscopy should be relegated to a secondary role in the workup of antibiotic-associated diarrhea.

Colonoscopy↗