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Biomedical subjects

J Maurer

Publications and source records attributed to J Maurer.

At least 73 records · Page 4Linked to original sources
PubMed1998

The influence of an arterial and venous air embolism on the hearing level in laboratory mini pigs.

We examined the influence of an experimental venous and arterial air embolism on the hearing level in laboratory mini pigs. Before and after the injection of air a threshold ABR was measured in anaesthetized mini pigs (n=15). A venous air embolism was performed in 6 animals: no changes in the hearing level or in the interpeak latencies Jewett wave V-I were observed in any of the animals before, during or after the application of air. In 9 animals the arterial embolism was done, 2 animals died and had to be excluded. In 6 animals out of 7 a hearing loss was observed starting after the injection of 40 ml air and finally ending in deafness for these 6 animals. The detected hearing loss is probably of cochlear origin, as no prolongations of the interpeak latencies of Jewett wave V-I at 90 dB HL were observed prior to the deafness. Our results show that air bubbles in the arterial circulation lead to cochlear damage ending in deafness. Our research indicates that decompression sickness, which is comparable to the arterial air embolism, is more often the cause of a sensorineural hearing loss after diving than previously believed.

Animals↗
PubMed1998

Predictors of quality of life and adjustment after lung transplantation.

STUDY OBJECTIVE: Few studies have examined predictors of quality of life and adjustment after lung transplantation. This study determined whether pretransplant psychological measures predicted physical health, quality of life, and overall adjustment posttransplant. Cross-sectional analyses also examined differences in adjustment and quality of life for lung transplant candidates and recipients. DESIGN AND PARTICIPANTS: Seventeen transplant candidates and 60 transplant recipients completed questionnaires measuring adjustment and quality of life. In addition, we examined archival data on 107 transplant candidates who had received pretransplant psychological assessments, and posttransplant physical health status data were collected on these patients. Of the 107 patients who provided a pretransplant psychological assessment, 32 completed the questionnaires measuring posttransplant adjustment and quality of life. SETTING: University medical center transplant service. RESULTS: Cross-sectional analyses indicated significantly better adjustment and quality of life posttransplant. Pretransplant psychological variables were not associated with measures of posttransplant physical health. Hierarchical multiple regression analyses found that pretransplant anxiety and psychopathology predicted posttransplant adjustment (beta's ranging from 0.32 to 0.68) and greater pretransplant anxiety also predicted worse posttransplant quality of life (beta's ranging from 0.29 to 0.62). Subjective sleep disturbances were associated with poorer adjustment and quality of life (beta's ranging from 0.36 to 0.75), and were found to mediate the relationship between presurgical anxiety and posttransplant adjustment and quality of life. CONCLUSIONS: This study found that psychological status pretransplant predicted adjustment and quality of life posttransplant. Moreover, increased anxiety levels pretransplant predicted subsequent subjective sleep disturbances, which were, in turn, associated with poorer adjustment and quality of life. The benefits of pretransplant stress management interventions are discussed.

Adaptation, Psychological↗
PubMed1998

Calcium channel blockers for prevention of noise trauma in otologic surgery.

One hundred patients were tested prior to otologic ear surgery in a prospective, randomized, double-blind study to assess the perioperative efficiacy of a calcium channel blocker (diltiazem) in preventing acoustical trauma during middle ear surgery. The patients were randomly divided into a therapy group (diltiazem), and a control group (placebo). Bone conduction hearing thresholds were examined preoperatively and followed at 1 day and 3 months postoperatively. Frequency-dependent changes in postoperative bone conduction and the number of patients with various degrees of postoperative hearing loss in both groups were statistically analyzed. The results indicated only a small postoperative hearing loss after ear surgery in both groups. There was a tendency for better results in the therapy group but this was not found to be statistically significant. Despite favorable results in animal trials utilizing different kinds of noise with the prophylactic application of diltiazem, further studies in humans will be needed to determine the role of calcium antagonist drugs in the prophylaxis or treatment of acoustical trauma.

Adolescent↗
PubMed1998

Activation of autologous lymphocytes of patients with chronic myelogenous leukemia in the chronic phase with cytokines and CD3 monoclonal antibody results in bcr/abl- blood leukocyte cultures as determined by reverse transcriptase-polymerase chain reaction.

To investigate the potential of autologous lymphocytes to eliminate chronic myelogenous leukemia (CML) cells following activation and targeting by CD3-monoclonal antibody, we cultured Ficoll-isolated peripheral blood cells from 11 patients with CML in the chronic phase in permutated combinations of interleukin (IL)-2, CD3-monoclonal antibody (OKT3), and interferon (IFN)gamma. The efficiency of CML cell elimination was studied by means of flow cytometry and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Cultures containing only OKT3 and IL-2, with or without IFNgamma, resulted in tumor cell reduction to the level of RT-PCR negativity. The length of the culture period required to reach a RT-PCR-negative state ranged from 3 to 33 days. A 1- to 2-log reduction in leukemic cells could be achieved by culture medium alone. In contrast, 3- to 4-log reductions in CML cells were observed following in vitro culture and ex vivo T cell activation with a given sensitivity for RT-PCR detection of 1 bcr/abl+ cell in 10(4). The feasibility of purging chronic myelogenous leukemia cells in a short time was associated with a low number of platelet counts (r=0.6457; p < 0.05). CML cell reduction was associated with expansion of CD25+/CD4+//CD8+/-/CD56+/- lymphocytes. These findings may be of relevance for immunotherapy procedures.

Adult↗
PubMed1997

A randomized controlled trial of verapamil on cyclosporine nephrotoxicity in heart and lung transplant recipients.

BACKGROUND: Cyclosporine (CsA) is a potent immunosuppressive drug widely used in organ transplantation and in the treatment of autoimmune diseases (1, 2). However, its common nephrotoxic effect is a major limiting factor. Short-term CsA treatment has been shown to cause reversible renal vasoconstriction, whereas long-term treatment can lead to an afferent arteriolopathy and chronic renal failure. METHODS: We performed a randomized controlled trial to examine the short-term renal effects of verapamil in 32 CsA-treated heart or lung transplant recipients. Sixteen patients each were randomized to receive a 6-week course of verapamil or control treatment (atenolol in hypertensive patients and placebo in normotensive patients) 1-2 months after transplantation. An 8-hr sequential clearance study of inulin and p-aminohippuric acid for estimating glomerular filtration rate and renal plasma flow, respectively, was performed at baseline and at completion of study. The integral area under the curve of the clearance parameter over 8 hr was then calculated to generate a clearance-time index. RESULTS: There was no difference in the clearance-time indices for inulin and p-aminohippuric acid between the two groups at baseline. However, at the completion of study, the within-group change in the glomerular filtration rate clearance-time index was different between the verapamil and control groups (48+/-20 vs. -35+/-17 ml/min/1.73 m2 x hr, respectively; P=0.0038). A similar trend was seen for renal plasma flow, but did not reach statistical significance. Mean arterial blood pressure and whole-blood CsA levels did not differ between the two groups during the study. Verapamil treatment was also associated with a decrease in CsA dose requirement (7.6+/-0.58 mg/kg/day at baseline vs. 4.6+/-0.40 mg/kg/day at completion; P<0.001) without any significant change in trough whole blood CsA levels. Rejection episodes did not differ between the two groups. CONCLUSIONS: The use of verapamil in the heart or lung transplant recipients may therefore provide both renal protective effects and cost savings.

Adult↗
PubMed1997

Characterization of nitric oxide synthase isoforms expressed in different structures of the guinea pig cochlea.

Nitric oxide synthase (NOS) activity and NADPH diaphorase staining has previously been reported in mammalian cochlea. Here we demonstrate immunoreactivity for neuronal-type NOS I and endothelial-type NOS III in the cochlea of the guinea pig. NOS I immunoreactivity was seen in inner and outer hair cells, and spiral ganglion cells. Staining for NOS I was also shown in basal and intermediate cells of the stria vascularis, spiral ligament cells, and the media of vessels near the modiolus. An antibody to NOS III stained primarily vascular endothelial cells. Some NOS III immunoreactivity was also detected in spiral ganglion cells. An antibody to the inducible-type NOS II did not stain any structure of the guinea pig cochlea, suggesting that this isoform is not expressed under physiological conditions. Nitric oxide produced by NOS I and/or NOS III may act as a neuromodulator in the organ of Corti and could also play a role as a regulator of cochlear blood flow.

Animals↗
PubMed1997

Alteration of loosely bound calcium in the guinea pig organ of Corti after treatment with diltiazem as calcium channel blocker.

After oral administration of the organic calcium channel blocker diltiazem to guinea pigs for 7 days, calcium ions were precipitated with potassium antimonate in the cochleae. The spatial distribution of the precipitates was studied by energy-filtering transmission electron microscopy and the amount of the ultrastructural reaction products formed was determined semiquantitatively by an image processing system. Compared with untreated control ears, the number of the formed precipitates was reduced drastically in the inner hair cells after diltiazem treatment. In addition, electron microscopic analysis revealed that the number of calcium precipitates attached at the basolateral membrane of the outer hair cells was clearly reduced when compared with untreated control specimens. A large number of histochemical reaction products could be identified in the basilar membrane and were also observed in the untreated control specimens. The spatial distribution of the calcium precipitates in the lamina reticularis was not affected by diltiazem treatment and calcium precipitates could be identified within different cell membranes. The techniques used was considered to be helpful for identifying calcium channels ultrastructurally in intact undissected tissues and to support light microscopic analyses and patch-clamp electrophysiological measurements.

Administration, Oral↗
PubMed1997

Electron microscopic localization of nitric oxide I synthase in the organ of Corti of the guinea pig.

Nitric oxide synthase (NOS) activity has been detected previously in the mammalian cochlea at a light microscopic level. Here we present results of electron microscopic analysis for post-embedding immunoreactivity of neural-type NOS I in the cochlea of the guinea pig. Strong enzyme immunoreactivity was identified in the cytoplasm of inner and outer hair cells. Gold-labeled NOS I antibodies were mainly located in electron-dense areas of the cytoplasm, whereas electron-lucent regions of the receptor cells were nearly free from any immunoreactivity. In both types of hair cells anti-NOS I antibodies were also visible in the cuticular plates, hair bundles and nuclei. Further ultrastructural analysis revealed that the submembranous cisternae of the outer hair cells were nearly free from any reaction product, demonstrating that the whole cytoplasm of this hair cell was not immunoreactive. Other NOS I immunoreactivity was identified in the cuticular plates of the inner and outer pillar cells and in the cytoskeletal elements located in the apical parts of Deiter cells, forming the lamina reticularis or in cytoskeletal-containing regions in basal Deiter cells. Anti-NOS antibodies were visible in the nuclei of various cell types. Our findings suggest that nitric oxide produced by NO I synthase in the organ of Corti may act as a modulator of hair cell physiology during the processes of signal transduction with frequency selectivity.

Animals↗
PubMed1997

Morphological and cytochemical findings in 150 cases of T-lineage acute lymphoblastic leukaemia in adults. German Multicentre ALL Study Group (GMALL).

We evaluated the morphological findings in 150 consecutive cases of T-lineage acute lymphocytic leukaemia (T-ALL). Cytochemistry including PAS staining and acid phosphatase reaction proved of limited value for the diagnosis of ALL. The diagnosis of acute leukaemia was easy to establish in most instances. However, in a few cases the leukaemic cells were difficult to recognize as blasts. The nuclei of such cells showed condensed chromatin and nucleoli were lacking, and was encountered particularly in thymic ALL. Basophilic cytoplasm combined with prominent vacuolization suggestive of mature B-ALL (ALL-L3 type), was observed in 16 cases. Other features, however, such as cell size, polymorphism, chromatin structure, sparse cytoplasm or focal positivity for acid phosphatase, excluded a diagnosis of ALL-L3 in those cases. Distinction from hybrid leukaemia was difficult in 20 cases, because of a low percentage of peroxidase-positive blasts or other features which suggested a separate myeloid leukaemia component. In nine of these the hybrid nature of the leukaemia was considered as certain on the basis of morphology. Seven cases had been diagnosed as biphenotypic with coexpression of myeloid and lymphoid markers by immunological techniques. In conclusion, our analysis showed some serious pitfalls of the morphology in T-ALL, clearly indicating the need for immunological analysis of the leukaemic cells. However, morphology remains an essential component of the diagnostic repertoire, especially when the marrow is difficult to aspirate and in cases with equivocal immunological findings. Furthermore, recognition of a separate myeloid leukaemic component in addition to the lymphatic one requires a morphological analysis.

Adult↗
PubMed1997

[Experiences with upper eyelid gold implantation in facial paralysis].

BACKGROUND: A lagophthalmus following facial nerve palsy is not only a cosmetic problem, but can also cause serious complications to the cornea, such as ulceration and perforation. A passive eyelid closure can be achieved by the implantation of a gold weight in the upper eyelid. METHODS: Within five years we performed 21 implantations of gold weights in patients with facial nerve palsy. RESULTS: In 19 patients (90%) good eyelid closure was achieved. In three patients the gold weight was removed for the following reasons: remission of paralysis, foreign body sensation, and wound infection. CONCLUSIONS: The insertion of an eyelid goldweight in the upper eyelid in patients with established facial palsy is an effective method of reducing the incidence of discomfort to the eye and corneal complications. The insertion is simple and performed under local anaesthesia, and is easily reversed or revised if necessary.

Adolescent↗
PubMed1997

Autodisplay: one-component system for efficient surface display and release of soluble recombinant proteins from Escherichia coli.

The immunoglobulin A protease family of secreted proteins are derived from self-translocating polyprotein precursors which contain C-terminal domains promoting the translocation of the N-terminally attached passenger domains across gram-negative bacterial outer membranes. Computer predictions identified the C-terminal domain of the Escherichia coli adhesin involved in diffuse adherence (AIDA-I) as a member of the autotransporter family. A model of the beta-barrel structure, proposed to be responsible for outer membrane translocation, served as a basis for the construction of fusion proteins containing heterologous passengers. Autotransporter-mediated surface display (autodisplay) was investigated for the cholera toxin B subunit and the peptide antigen tag PEYFK. Up to 5% of total cellular protein was detectable in the outer membrane as passenger autotransporter fusion protein synthesized under control of the constitutive P(TK) promoter. Efficient presentation of the passenger domains was demonstrated in the outer membrane protease T-deficient (ompT) strain E. coli UT5600 and the ompT dsbA double mutant JK321. Surface exposure was ascertained by enzyme-linked immunosorbent assay, immunofluorescence microscopy, and immunogold electron microscopy using antisera specific for the passenger domains. In strain UT2300 (ompT+), the passenger domains were released from the cell surface by the OmpT protease at a novel specific cleavage site, R / V. Autodisplay represents a useful tool for future protein translocation studies with interesting biotechnological possibilities.

Adhesins, Escherichia coli↗
PubMed1997

Lack of left ventricular dysfunction associated with sustained exposure to hyperlipidemia following lung transplantation.

OBJECTIVES: Hyperlipidemia due to standard immunosuppressive agents occurs commonly following solid organ transplantation. A decision to treat hyperlipidemias would be based on the assumption that such disorders lead to accelerated atherogenesis and ultimately to cardiac dysfunction. We therefore sought to examine whether hyperlipidemias following lung transplantation were associated with a decline in left ventricular (LV) function. STUDY DESIGN: We retrospectively reviewed serial echocardiograms, radionucleotide angiograms (RNAs), and serum lipid levels following lung transplantation. Results of cardiac studies were defined as abnormal if a decline in LV grade occurred from the best result at any time postoperatively to the most recent study. PATIENTS: A total of 184 patients with transplants between November 1983 and June 1995 were reviewed. Eighty patients were excluded owing to incomplete data. One patient was excluded because of severe perioperative myocardial dysfunction. RESULTS: Approximately 80% of patients had elevated cholesterol levels and 60% had elevated low-density lipoprotein levels. Triglyceride levels were raised in 34% of patients while only 4% had an abnormal serum high-density lipoprotein level. More than 80% of patients had no evidence of LV abnormalities in either RNA or echocardiographic studies (group 1). One patient had a change in echocardiographic LV function but no change in grade of RNA (group 2). Twenty patients had a decline in grade based on RNA but no change in the echocardiogram (group 3). There were no patients with changes in both RNA and echocardiogram (group 4). All changes in LV function were from grade I to II. The mean period of follow-up exceeded 30 months for patients in groups 1 to 3. Follow-up data at 3, 4, and 5 years were available on 47, 23, and 12 patients, respectively. There were no differences between the proportions of subjects with normal and abnormal serum lipid levels in each group. CONCLUSIONS: In the initial 5 years after lung transplantation, dyslipidemias affect the majority of patients but are not associated with evidence of deteriorating LV function.

Anticholesteremic Agents↗
PubMed1997

Practical method for determination of the U status of S-s- erythrocytes.

Red blood cells (RBCs) lacking S and s blood group antigens are classified as S-s-U- or S-s-U+var but the classification may vary due to the characteristics of anti-U and to the technique used. Tests on RBCs known to lack glycophorin B (GPB) or to possess an altered form of GPB showed that polyethylene glycol-indirect antiglobulin testing or MicroTyping Systems (MTS)-gel techniques can be used as a simple and reliable way to detect RBCs with variant forms of GPB. This approach can be important in the selection of rare RBCs for transfusion to patients with undifferentiated anti-U.

Journal Article↗
PubMed1997

The six-minute walk test: a guide to assessment for lung transplantation.

BACKGROUND: A window of opportunity exists with regard to optimal timing for lung transplantation. Performance of a transplantation too early may rob the patient of months to years of survival, whereas waiting too long increases the risk of death before transplantation. Several studies have examined specific lung function tests as predictors of death, but none have been shown to be useful across the various disorders leading to end-stage lung disease. We therefore sought to examine the usefulness of the 6-minute walk test as a guide to assessment for transplantation. METHODS: We conducted a retrospective chart review of patients who were assessed and either were accepted or died waiting acceptance by the Toronto Lung Transplant Program between January 1991 and June 1995. One hundred forty-five patients with the following lung diseases were included: emphysema (n = 38), alpha-1-antitrypsin deficiency (n = 20), idiopathic pulmonary fibrosis (n = 26), primary pulmonary hypertension (n = 10), Eisenmenger's syndrome (n = 9), and cystic fibrosis (n = 41). The sensitivity, specificity, and positive and negative predicted values for a 6-minute walk distance of 300 and 400 m as a predictor of death were calculated. RESULTS: Mortality rates were as follows: emphysema (7.9%), alpha-1-antitrypsin deficiency (15%), idiopathic pulmonary fibrosis (42.3%), primary pulmonary hypertension (50%), Eisenmenger's syndrome (11%), and cystic fibrosis (24.4%). A 6-minute walk distance of less than 400 m had the following characteristics for prediction of death: sensitivity 0.80, specificity 0.27, positive predictive value 0.27, and negative predictive value 0.91. Similar findings for a 6-minute walk distance of less than 300 m were as follows: 0.52, 0.80, 0.38, and 0.88, respectively. CONCLUSION: The 6-minute walk test is a useful tool in the assessment of when to list patients for transplantation. A 6-minute walk test result of less than 400 meters appears to be a reasonable marker with regard to when a patient should be listed for transplantation.

Adult↗
PubMed1997

Tympanic membrane displacement analysis after glycerol intake: effects on intracranial and intracochlear fluid pressure.

BACKGROUND: Intracranial pressure is transmitted to the perilymph of the cochlea via the cochlear aqueduct and to the endolymph via Reissner's membrane. The tympanic membrane displacement analyzer (TDA) is a new system that may provide a useful, noninvasive, indirect method to identify intracranial and intracochlear pressure changes. METHODS: We performed measurements in 20 persons with normal hearing and in 29 patients with various unilateral diseases of the inner ear such as sudden hearing loss or Meniere's disease. Another series of measurements were done in 15 normal-hearing persons and in 15 patients with Meniere's disease before and after oral ingestion of glycerol. RESULTS: In the first series of measurements, no significant differences in the tympanic membrane displacement were found between normal-hearing individuals and patients with unilateral diseases of the inner ear. In the second series, in all individuals a temporary, relative decrease in intracochlear pressure was found after oral ingestion of glycerol but without any significant difference between the two groups. CONCLUSIONS: These results revealed that the TDA is apparently not useful in the evaluation of patients having Meniere's disease.

Acoustic Impedance Tests↗
PubMed1996

Cytolytic therapy for the treatment of bronchiolitis obliterans syndrome following lung transplantation.

Bronchiolitis obliterans syndrome (BOS) is a common occurrence following lung transplantation and is one of the most important impediments to long-term graft viability. Cytolytic therapy has been used as treatment for BOS, but there is little data documenting efficacy. Furthermore, these agents have been associated with significant adverse effects. Charts of 15 patients who received an antilymphocyte preparation (ALP) for BOS were reviewed. Forced expiratory volume-1 second (FEV1) and stage of BOS were compared before and after treatment. Complications of ALP were recorded from the charts. Two of 15 patients had an improvement in FEV1, 5/15 exhibited no change, and 8/15 continued to decline. There was no pattern associating stage of BOS with likelihood of response to ALP. All patients received antimicrobial prophylaxis and did not experience infectious complications following administration of the ALP. ALP for the treatment of BOS results in an arrest or improvement of FEV1 in approximately 50% of patients. Infectious complications are uncommon when antimicrobial prophylaxis is administered.

Adult↗