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Biomedical subjects

D Krieger

Publications and source records attributed to D Krieger.

At least 73 records · Page 4Linked to original sources
PubMed1987

Evaluation by MRI of paraparesis and tetraparesis of undiagnosed aetiology.

The clinical, neuroradiological, electrophysiological and CSF findings of seven patients with slowly progressive paraparesis or tetraparesis are presented. In all patients, the results of the tests performed, including evoked potentials, CT scanning, oligoclonal bands in the CSF and myelography, were normal or inconclusive and did not lead to the correct diagnosis of the aetiology. In contrast, magnetic resonance imaging (MRI) provided the diagnosis of the causative process: multiple sclerosis in four cases, meningioma of the craniocervical junction or upper thoracic spinal cord in two cases, and upper cervical cord low-grade astrocytoma in one case. The patients with tumour could be treated effectively. Without MRI, however, the correct diagnosis would have been delayed. T2-weighted spin-echo scans provided maximal sensitivity for the detection of MS plaques, although they lacked specificity for a special disease. Several morphological criteria during MRI were helpful in differentiating Binswanger's disease, leucodystrophy and adrenoleucodystrophy from MS. It is concluded that at present MRI is the only non-invasive test with which to screen reliably the craniocervical junction and the upper cervical level, both of which are diagnostically difficult regions. The case histories also demonstrate that MRI is essential in all patients where a full clinical evaluation of the suspected spinal segment is not possible. "Pure spinal MS" is a misleading diagnosis and should not be accepted without confirmation by MRI. MRI has to be performed early enough to permit timely treatment of spinal and brain-stem disorders.

Adult↗
PubMed1987

High frequency scalp potentials evoked by a reaction time task.

'Bursts' of high frequency (20-80 Hz) extracellular electrical activity are the signature of the brain mechanism mediating recognition of odors in rabbits and cats. To test the hypothesis that a similar mechanism may be functional in man outside the olfactory system, relationships were studied between bursts of 20-150 Hz scalp EEG and parameters of performance during visual reaction time tasks. Specific findings indicated that (1) muscle artifacts were not the primary source of identified EEG bursts, (2) the mechanism which produces the bursts may be similar in both rabbit olfactory bulb and human neocortex, (3) visual task performance may be mediated by the brain areas which produced the bursts, and (4) burst activity varied with changes in performance which may be associated with attention and learning.

Adult↗
PubMed1986

Bacterial colonization of intrauterine devices (IUDs).

The bacterial colonizing of the intrauterine device (IUD) and its tail were studied in 152 IUDs obtained from 70 symptomless IUD wearers, 13 women with dysfunctional bleeding, 23 women with pelvic inflammatory disease, 31 women in whom the tail of an IUD was no longer visible and 17 women who were pregnant with an IUD in situ. The IUDs were either removed by the transcervical route or through a fundal incision in the uterus after hysterectomy. Most IUD were heavily contaminated by bacteria, especially Staphylococcus epidermidis, Enterococci and anaerobic Lactobacilli. The number of colonies was higher in women with dysfunctional bleeding and pelvic inflammatory disease than in others with a predominance of pathogenic bacteria, namely beta-hemolytic Streptococci, Staphylococcus aureus and Escherichia coli. Almost half of the IUDs without a tail protruding through the cervix were sterile. With pregnancy in the presence of an IUD, 71% of devices grew bacteria which were mainly anaerobic.

Bacteria↗
PubMed1986

Automatic enhancement of single evoked potentials.

Using EEG data acquired during a simple (sRT) or choice (cRT) reaction time task we tested a signal enhancement technique. Our findings indicate that the signal enhancement technique under study substantially reduced background activity while retaining physiologically significant information. For each RT trial, a pre-stimulus epoch was modeled using a canonical variate analysis (CVA) system identification technique to produce a filter. This filter was then applied to the post-stimulus epoch to remove ongoing background activity. Signal/noise enhancement was apparent from comparison of the ensemble averages of seven raw responses and the 7 corresponding CVA-enhanced responses. The extracted single evoked potentials (sEPs) were searched by machine algorithm for an expected negative peak with approximately 200 msec latency, the latency of each identified peak estimated, and correlations between RT and peak latency computed. For the choice task significant correlations were found at the right central placement (C4) for left-handed responses and at the left parietal placement (P3) for right-handed responses. For the simple task with right-handed response, the most significant results were found at left placements (C3 and T5) with additional significant findings bilaterally (T3, T4, P4 and O1).

Electroencephalography↗
PubMed1983

Antimicrobial prophylaxis in acute leukaemia: prospective randomized study comparing two methods of selective decontamination.

In a prospective study the efficacy of two regimens for selective decontamination of the digestive tract was studied in patients with acute leukaemia during remission induction therapy. Seventy-eight patients were randomized to receive either a combination of cotrimoxazole, polymyxin B and nystatin (group A) or a combination of nalidixic acid, polymyxin B, neomycin and nystatin. With both regimens the gastrointestinal tract could be decontaminated equally effectively from potential pathogens. In the oropharyngeal region the decontamination from Enterobacteriaceae was significantly better in group A (P less than 0.01). In both groups less than 10% of the acquired infections were caused by gram-negative bacilli and no gram-negative septicaemia occurred in either group. The median time interval until the first acquired infection was 17 days in group A and 36 days in group B, respectively (P less than 0.05). It is concluded that regimen A might be more effective than regimen B though both regimens prevent reliably severe gram-negative infections.

Acute Disease↗
PubMed1982

Beta-endorphin is present in the male reproductive tract of five species.

Previous studies from this laboratory have demonstrated immunostainable beta-endorphin-like material (beta-EP) in Leydig cells and epithelia of the epididymis, seminal vesicle and vas deferens of the rat. These observations would be strengthened if it could be demonstrated that they were not a peculiarity of the rat. Accordingly, we now present immunocytochemical evidence for the presence of beta-EP in the Leydig cells of mouse, hamster, guinea pig and rabbit. No immunoreactive material was identified in Sertoli, myoid, endothelial or germ cells of any of the species examined. Immunostainable beta-EP was also demonstrated in the epididymides of mouse, guinea pig, rabbit, and rat, but not hamster. Immunostainable material was also present in the epithelia of the vas deferens and seminal vesicles of mouse and rat, the only two species thus far examined. Since beta-EP was present in Leydig cells, we wondered whether this peptide could be identified in other steroid-producing tissues. When rat ovaries and adrenals were reacted with anti-beta endorphin, staining was demonstrated in corpus luteum and adrenal cortex. No staining was observed in the adrenal medulla or other portions of the ovary. In order to determine whether the beta-EP detected in the testis and epididymis was derived from a pituitary source, animals were hypophysectomized and tissues examined 2 weeks later. Both the Leydig cells and the epididymal epithelium remained immunostainable. In summary, immunostainable beta-EP has been identified in Leydig cells of five species. Stainable material is also present in the epithelium of other portions of the male reproductive tract and in steroid-secreting cells of the ovary and the adrenal. Such beta-EP may have a paracrine function in the testis and other portions of the male reproductive tract.

Adrenal Glands↗
PubMed1982

Infection prophylaxis in acute leukaemia patients: comparison of selective and total antimicrobial decontamination of the gastrointestinal tract.

In a retrospective study, total antimicrobial decontamination with strict reverse isolation (ITD) and selective decontamination without isolation (SD) were compared as means of preventing infection in patients with acute leukaemia. Thirty patients were treated with ITD and 34 patients with SD. The surveillance cultures indicated that aerobic gram-negative bacilli and yeast could be equally eliminated effectively in both the groups. The anaerobic flora was only minimally influenced by SD. The incidence of acquired infections was 1.17 per patient in group ITD as compared to 0.85 in group SD. In group ITD, acquired bacterial infections were mostly caused by gram-negative bacilli (63%) whereas in the group SD these microorganisms accounted only for 25% of the infections. In group SD the total number of fever days was significantly lower and the mean duration of pyrexial episodes was substantially shorter. The results indicate that SD is an effective and inexpensive method for preventing gram-negative infections and might be at least as effective as ITD.

Acute Disease↗
PubMed1981

Risk factors for infections of the oropharynx and the respiratory tract in patients with acute leukemia.

The pathogenicity of microorganisms isolated by surveillance cultures, the neutrophil count in the peripheral blood, and the interaction of the two factors were analyzed as risk factors for infections of the oropharynx and the respiratory tract in patients with acute leukemia being treated in strict reverse isolation under antimicrobial modulation. A statistical method was developed for the identification of bacteria, the presence of which was correlated with an increased risk of infection. A significantly increased risk was found mainly for species of Klebsiella, Enterobacter, Proteus, and Pseudomonas. The degree of neutropenia was significantly correlated with the risk of infection, which was influenced by the microbiologic state of the oropharynx. Thus, patients with gram negative bacilli had significantly more days with infection at all levels of neutropenia than patients without gram-negative bacilli. These two risks factors were additive but did not potentiate each other.

Acute Disease↗
PubMed1980

The efficiency of strict reverse isolation and antimicrobial decontamination in remission induction therapy of acute leukemia.

The efficiency of strict reverse isolation and antimicrobial decontamination in remission induction therapy of acute leukemia was studied retrospectively in 47 patients who were treated with a standardized aggressive chemotherapy of daunorubicin and cytosine arabinoside. Twenty-two patients were treated in strict reverse isolation with antimicrobial decontamination and 25 patients in the open ward without any measures against infections. In the patients in isolation the incidence of new infections per patient was 0.77 compared to 1.42 in the control group. The rate of complete remissions was 77% in the patients in isolation vs. 56% in the control patients.

Acute Disease↗
PubMed1978

Protective isolation and antimicrobial decontamination in patients with high susceptibility to infection. A prospective cooperative study of gnotobiotic care in acute leukaemia patients. III: The quality of isolation and decontamination.

In a cooperative study, the quality of protective isolation and of antibiotic decontamination of the digestive tract was studied in patients with acute leukaemia by (bio)-typing of Enterobacteriaceae species, Pseudomonas aeruginosa and Staphylococcus aureus isolated from oral washings and faecal samples. These samples were collected before and during treatment of 82 patients who were either isolated and decontaminated for which latter purposes a combination of neomycin, polymyxin, bacitracin and nystatin was used (group A); isolated without decontamination (Group B) or treated on the ward without decontamination (Group C). The results indicated that protective isolation had only been completely successful during the entire (remission induction) treatment period in one of the 32 patients in Group B. In Group A patients, who underwent antibiotic decontamination in addition, successful isolation was achieved in 57% of 28 patients. Successful antibiotic decontamination of the digestive tract for the entire treatment period as far as all potentially pathogenic species are concerned, was realized in 4 (14%) of the 28 patients of Group A. Bacteriologically confirmed infections occurred in 50% of Group A patients, in 59% Group B patients and in 64% of Group C patients. It is concluded that the quality of isolation had in general been insufficient but that it was improved by oral nonabsorbable antibiotics and, furthermore, that the antibiotic decontamination procedure also requires improvement.

Adolescent↗
PubMed1977

The location of secondary structure in histone H4.

A total of eight peptides cleaved from calf thymus histone H4 have been studied at several ionic strengths by circular dichroic, infrared and nuclear magnetic resonance spectroscopies to follow the formation of alpha helix, beta structure and self-aggregates. The results are compared with data obtained previously on three other peptides and on the intact molecule in order to define the location of secondary structure in histone H4. It is concluded that there are two alpha-helical sections, the first from residues 55 to 67 and the second of about 12 residues in the region between residues 70 to 90. beta-Structure formation takes place only in the C-terminal part of the intact H4 molecule. Nuclear magnetic resonance studies of the peptides prove that it is the basic N-terminal regions of histone H4 that remain free when the molecule self-aggregates.

Animals↗