PubMed Health⌕ Search

Biomedical subjects

K Brandt

Publications and source records attributed to K Brandt.

At least 37 records · Page 2Linked to original sources
PubMed1999

Postoperative irradiation: are there long-term effects on nerve regeneration?

This study investigates the histomorphologic and functional effects of external-beam irradiation on peripheral nerve regeneration in the rat model. All animals received a 1.5-cm interposition isogeneic nerve graft to the right posterior tibial nerve. Group 1 animals served as controls and Groups 2 and 3 received fractionated postoperative irradiation doses of 66 and 106 Gy, respectively. All animals were evaluated for functional recovery with monthly walking-track analysis. At the end of 8 months, the animals were sacrificed and segments of the grafted and distal nerve were harvested for histomorphologic analysis. A statistically significantly fewer number of axons were found in the distal segment of the irradiated specimens, compared to controls. There was no significant difference in the nerve-fiber density of the grafted or distal segments, compared to controls. Functional evaluation by walking-track analysis showed no difference between the irradiated groups and controls over the length of the study. These results suggest that acute nerve grafting of nerve defects in the face of planned postoperative irradiation is safe.

Animals↗
PubMed1999

The effects of cisplatinum and vincristine on peripheral nerve regeneration.

Current treatment modalities for extremity sarcoma often include tumor extirpation plus neoadjuvant therapy. Limb-sparing surgery may require reconstruction of critical nerve defects. Neurotoxic side effects from adjuvant chemotherapy have been reported and raise concerns regarding the effects of chemotherapy on nerve regeneration. In an attempt to define the effects of adjuvant chemotherapy on peripheral nerve regeneration, cisplatin and vincristine were administered to rats following isografting of the posterior tibial nerve. Parameters used to assess peripheral nerve regeneration included walking track analysis and histomorphology. Sixty 250-g Sprague-Dawley rats were randomly allocated into one of three treatment groups. Each animal underwent a 15-mm reversed interposition nerve isograft from 30 donor rats into the right posterior tibial nerve. Ten animals served as control. The remaining animals were divided into two groups of 25 animals each. One group received cisplatin (75 mg/m2) and the other group received vincristine (1 mg/m2). Chemotherapy was administered at 4-week cycles for a total of six cycles (24 weeks). Walking track analysis was performed monthly. Nerve specimens were harvested from the grafted segment and the distal posterior tibial nerve for histomorphology. Walking track analysis demonstrated no statistical difference in print length between the control and chemotherapeutic groups at the conclusion of the study. The number of axons per square millimeter and nerve fiber density were not statistically different between control and chemotherapeutic groups. In the rodent posterior tibial nerve model, postoperative adjuvant therapy does not significantly alter functional outcome in peripheral nerve regeneration. The practice of immediate nerve grafting after tumor extirpation, despite planned postoperative chemotherapy, is supported.

Animals↗
PubMed1999

Minimal inhibitory effect of male urine on detection of Chlamydia trachomatis by Roche Amplicor PCR.

A total of 1120 specimens of fresh urine from male patients was tested for Chlamydia trachomatis with the Roche Amplicor PCR Kit and an in-house PCR assay. The in-house PCR had an internal control to monitor inhibitory effects of clinical specimens on the PCR assay. All urine samples were processed within 24-48 h of collection and DNA was extracted on the same day that the assays were performed. Specimens that gave discrepant PCR results were tested by a reference laboratory with both the Roche Amplicor kit and their in-house PCR assay. Of the 1120 samples, 174 gave positive results in both assays and 942 gave negative results in both assays. Only one specimen showed an inhibitory effect on the in-house PCR assays, as indicated by failure to produce the internal control PCR product. This specimen gave negative results by both assays. There were four discrepant results in the two PCR assays. One was a false negative result obtained with the Roche Amplicor kit and the remaining three discrepant results could not be resolved because there was an insufficient quantity of specimen. This study demonstrated that the Roche Amplicor kit could effectively detect C. trachomatis in urine specimens from this population of male patients with negligible inhibition of PCR.

Bacteriuria↗
PubMed1998

Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration.

We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve, long bone, intestine, or blood vessel.

Biocompatible Materials↗
PubMed1998

The effects of preoperative irradiation on peripheral nerve regeneration.

The purpose of this study was to evaluate the effects of preoperative external cobalt60 beam irradiation on nerve regeneration. Ninety 250-g male Sprague-Dawley rats were studied. Peripheral nerve regeneration was measured by walking track analysis and histomorphology of the proximal, grafted, and distal nerve segments. Ninety animals were randomly assigned to one of five treatment groups, receiving a total fractionated dose of 30, 50, 70, and 90 Gy. Each animal received a 15-mm interposition nerve graft into the right posterior tibial nerve 6 weeks following completion of radiation therapy. The left leg served as a control. The remaining 10 animals received a nerve isograft subjected to a single dose of 30 Gy prior to placement (group 5). Walking track analysis was performed monthly through 8 months. At the conclusion of 120 and 240 days, sections of the proximal, grafted, and distal nerve were harvested, stained, and examined histomorphologically. Evaluation of the print length index demonstrated no statistical difference between our previously established nonirradiated controls, the irradiated groups, and the irradiated isograft group (group 5). The total number of axons per square millimeter was significantly decreased in the distal segment of all irradiated groups when compared with the controls. No statistical difference in number of axons per square millimeter was noted in the irradiated isograft group. Furthermore, no statistical difference was noted in the nerve fiber density between the control group, the preoperative irradiated groups, or the irradiated isograft group (group 5). Despite the reduction in myelinated regenerating fibers, no reduction in function was observed as measured by walking track analysis. Thus, immediate reconstruction of peripheral nerve defects in the face of preoperative irradiation may not be contraindicated.

Animals↗
PubMed1997

Partial purification of (1,3)-beta-glucan synthase from Candida albicans.

(1,3)-beta-Glucan synthase from Candida albicans was solubilized from microsomal membranes using the detergent 3-[(3-cholamidopropyl) dimethylammonio]-1-propane sulfonate (Chaps). Effective solubilization was dependent upon the strain and the method used to detect enzyme activity. The solubilized enzyme was purified over 765-fold using a modified product entrapment technique. Bovine serum albumin, an activator of glucan synthase, precipitated proteins during product entrapment and was replaced with BSA immobilized on agarose beads. SDS-PAGE analysis revealed a prominent 187-kDa band present in the product entrapped pellet as well as several additional polypeptides at 227, and 187, 182 and 39 kDa which were not prevalent in crude preparations.

Candida albicans↗
PubMed1997

Peripheral nerve regeneration: the effects of postoperative irradiation.

The purpose of this study was to evaluate the effects of postoperative external cobalt-60 beam irradiation on nerve regeneration. Sixty-five 250-gm male Sprague-Dawley rats were studied. Peripheral nerve regeneration was measured by walking track analysis and histomorphology of the proximal, graft, and distal nerve segments. These 65 animals underwent a 1.5-cm interpositional nerve graft into the right posterior tibial nerve. The left leg served as a control. Each animal was then randomly allocated into one of four groups. Group 1 served as control. Groups 2 through 4 were subjected to external cobalt-60 gamma-ray irradiation through a 2.5-cm circular portal for a total fractionated dose of 30, 50, and 70 Gy beginning on postoperative day 3. Radiation was administered in 2-Gy fractions, 5 fractions per week, with a top-up dose of 16 Gy given at the end of the fractionated irradiation. Walking track analysis was performed at 30, 60, 90, and 120 days after nerve grafting. At the conclusion of 120 days, sections of the proximal, grafted, and distal nerve were harvested, stained, and examined histomorphologically. Hematoxylin and eosin stains also were obtained. Evaluation of the print-length index demonstrated no statistical difference between the unirradiated controls and the irradiated groups. The total number of axons per square millimeter and nerve fiber density per square millimeter were significantly decreased in the distal segment of all the irradiated groups when compared with controls. Despite the reduction in myelinated regenerating fibers, no reduction in function was observed, as measured by walking track analysis. We would therefore recommend immediate reconstruction of peripheral nerve defects in the face of postoperative irradiation.

Animals↗
PubMed1997

Comparison of the Sanofi Diagnostics Pasteur Chlamydia Microplate EIA shortened assay with the original standard assay and cell culture.

The new Sanofi Diagnostics Pasteur Chlamydia Microplate EIA shortened assay was evaluated by comparison with the original standard assay and cell culture. A total of 853 paired male and female genital tract specimens was tested with both Sanofi Chlamydia Microplate EIA shortened and standard assays and the results were compared with those of cell culture. For confirmation, a blocking assay run in the shortened format was used. Discrepancies between the three methods were resolved by a direct fluorescent antibody (DFA) test on the EIA samples or the culture retentate, or both. After resolution of discrepant results, the standard assay had a sensitivity, specificity, positive predictive value and negative predictive value of 98.5%, 100%, 100% and 99.9%, respectively. The shortened assay results were 100%, 100%, 100% and 100%, respectively. The shortened assay takes approximately 1.5 h less time than the standard assay and this study demonstrated that they have equivalent sensitivity and specificity. The improvement in turnaround time enables results to be reported on the same day.

Cells, Cultured↗
PubMed1997

Characterization of a lipopeptide-resistant strain of Candida albicans.

Lipopeptides are antifungal agents that inhibit cell wall beta-(1,3)-glucan biosynthesis in fungal organisms. A mutant resistant to lipopeptides was generated by UV mutagenesis and characterized. The Candida albicans mutant (LP3-1) was stable and showed resistance specificity to a broad range of lipopeptides and certain glycolipid inhibitors. Other antifungal agents with diverse modes of action had a normal minimum inhibitory concentration profile for LP3-1 compared with the wild-type strain (CCH 442). In the in vitro beta-(1,3)-glucan synthase assay, both the lipopeptides and papulacandin-related agents had considerably higher 50% inhibitory concentration values in the LP3-1 strain than in the wild-type strain. In reconstitution assays, the resistance factor was associated with the integral membrane pellet rather than the peripheral GTP-binding protein. The LP3-1 strain had a membrane lipid profile similar to that of the parent strain and was virulent in a murine model of systemic candidiasis. Taken together, these results indicate that the resistance factor is associated with the integral membrane component of beta-(1,3)-glucan synthase. Lipopeptides are common antifungal agents encountered during screening of natural products. The LP3-1 strain was resistant to natural product extracts known to contain various lipopeptides. Thus, LP3-1 can be used in a dereplication assay.

Animals↗
PubMed1997

Do chronic middle cerebral artery stenoses represent an embolic focus? A multirange transcranial Doppler study.

BACKGROUND AND PURPOSE: It remains uncertain whether the annual stroke risk of 7% to 8% in middle cerebral artery (MCA) stenosis is of embolic or hemodynamic origin. Preliminary reports provide evidence of emboli exiting from acute MCA stenoses, detected by transcranial Doppler (TCD) sonography. With multirange monitoring before and after the stenosis, TCD monitoring may help for the first time to differentiate microemboli exiting from the MCA stenosis from those with a source proximal to the MCA stenosis. We searched for microembolic signals (MES) using multigated monitoring in patients with chronic MCA stenoses. METHODS: Fifty-eight patients with 78 chronic stenoses of the MCA were enrolled in the study. Additional sources of embolism were ruled out by extensive clinical workup. Twenty-four patients were treated with coumarin, whereas 28 patients received aspirin. The remaining 6 patients discontinued their medication after a few weeks. The sample volume of the multirange probe was placed on either side of the stenotic area of the MCA. RESULTS: Twenty-three (29.5%) of the stenoses were low grade, 18 (23%) were moderate, and 37 (47.5%) were severe. Thirty-seven (47%) of the stenoses were symptomatic and 41 (53%) were asymptomatic before study entry. During follow-up, 2 strokes and 7 transient ischemic attacks occurred. Computer tomography revealed two watershed-type infarcts. Sufficient insonation of the prestenotic and poststenotic segments of the MCA was possible in 70 stenoses (90%). No MES could be detected during a total of 1740 minutes' monitoring time distal to the MCA stenoses, regardless of the patients' medication. MES were also absent in the contralateral MCA. CONCLUSIONS: MES are not detectable in patients with chronic MCA stenoses of different degrees. No MES were found in either symptomatic or asymptomatic stenoses, regardless of the patients' medication. These results indicate that chronic MCA stenoses do not represent a significant embolic source. The absence of MES in the prestenotic Doppler sample volume, the watershed-type infarcts during follow-up, and the absence of small-vessel disease on computed tomography suggests that hemodynamic mechanisms are responsible for recurrent cerebral ischemia.

Aged↗
PubMed1997

Recommendations for a core set of outcome measures for future phase III clinical trials in knee, hip, and hand osteoarthritis. Consensus development at OMERACT III.

Significant progress has been made in outcome measurement procedures for osteoarthritis (OA) clinical trials, and guidelines have been established by the US Food and Drug Administration, European League Against Rheumatism, the World Health Organization/International League of Associations for Rheumatology, and the Group for the Respect of Ethics and Excellence in Science. However, there remains a need for further international harmonization of measurement procedures used to establish beneficial effects in Phase III clinical trials. A key objective of the OMERACT III conference was to establish a core set of outcome measures for future phase III clinical trials. During the conference, using a combination of discussion and polling procedures, a consensus was reached by at least 90% of participants that the following 4 domains should be evaluated in future phase III trials of knee, hip, and hand OA: pain, physical function, patient global assessment, and, for studies of one year or longer, joint imaging (using standardized methods for taking and rating radiographs, or any demonstrably superior imaging technique). These evidence based preferences, achieved with a high degree of consensus, establish an international standard for future phase III trials and will also facilitate metaanalysis and Cochrane Collaborative Project goals.

Clinical Trials, Phase III as Topic↗
PubMed1997

[Demonstration of immunoglobulin isotypes in the vitreous body as a contribution to the etiology of recurrent equine uveitis].

The functional properties of different immunoglobulin isotypes in equine recurrent uveitis (ERU) has not been investigated yet. Here, we describe the quantitative determination of total immunoglobulin levels and isotype differentiation in the vitreous of four horses with ERU as compared to that of seven healthy horses. In contrast to almost equal amounts of total immunoglobulin in the vitreous of both groups, remarkable differences were found: All four of the horses with ERU had significantly higher IgA contents in their vitreous as compared to the control group. However, the other isotypes monitored (IgM, IgGa, IgGb, IgGc and IgG(T)) indicated no differences between both groups. Comparing the individual ratios of immunoglobulin isotypes in the vitreous and the autologous serum of two horses with ERU and two control animals provided informative results: IgM was only detected in serum but not at all in vitreous of all horses investigated. All four IgG isotypes monitored in the diseased animals as well as these IgG isotypes and the IgA in healthy animals were present in the same ratios in serum and in vitreous of the individual horses. In general, the content of such isotypes in the vitreous was about 1000 fold lower then the respective isotypes in the autologous serum. These results are compatible with a transfer of the IgG and IgA isotypes from the serum into the vitreous in healthy individuals. All four horses with ERU, however, had a selectively increased relative IgA content in the vitreous as compared to their serum. This argues for a preferential local IgA production within the framework of a local immunological reaction to antigens located within the eyes of horses with ERU.

Animals↗
PubMed1996

Free flaps as flow-through vascular conduits for simultaneous coverage and revascularization of the hand or digit.

In complex extremity injuries, which include volar skin loss and ischemic digits, simultaneous coverage and revascularization are required. In this series of 12 patients, free-tissue transfers were utilized to provide both soft tissue coverage and a flow-through arterial conduit for revascularization. Eleven cases involved the hand or digits, and one case involved the great toe. Six cases were performed for acute ischemia associated with traumatic soft-tissue loss. The remaining six flaps were utilized to lengthen contracted vascular pedicles and provide vascularized soft-tissue coverage during reconstruction of severe hand and foot contractures. Nine temporoparietal fascia free flaps were used for hand or digit revascularization. Two fillet flaps were created, one from a nonreplantable foot and another from an isolated index amputation. The distal end of the axial artery of the flap was anastomosed to a digital artery to restore circulation. Fascial flaps were covered with full-thickness skin grafts. Primary wound healing was achieved in all patients. There were no flap losses or other complications. All the distal parts were revascularized adequately by the axial arteries of the flaps, and functional recovery was good. In this technique, the flap satisfied the need for both coverage and revascularization. Vein grafts were not needed. This series further describes the utility of flow-through flaps in the revascularization of digits.

Adolescent↗
PubMed1995

Supplemental phytic acid and microbial phytase change zinc bioavailability and cadmium accumulation in growing rats.

Three groups of individually housed albino rats (n = 6 each, initial average weight = 47 g) were fed diets based on egg white and corn starch over a 4-week period. All diets were supplemented with 15 mg/kg of Zn and 5 mg/kg of Cd. Group I (Control) was fed the basal diet free of phytic acid (PA) and phytase. By replacing corn starch by 0.5% PA (as NaPA) in groups II and III, a molar PA/Zn ratio of 33 was obtained. In group III, 2000 U of microbial phytase per kg diet were added. Addition of PA to diet (group II) resulted in a significant decrease in growth and zinc status. The negative effect of dietary PA on growth and zinc status was considerably counteracted by the supplementation of 2000 U microbial phytase (group III). In group I the highest apparent zinc absorption (58.2%) was measured. The addition of 0.5% PA (group II) significantly decreased apparent zinc absorption to 23.4%. In rats receiving the phytase-enriched diet (group III) 46.5% of ingested zinc was apparently absorbed. Liver cadmium concentration in rats fed the diet containing PA was significantly higher than that in the control group, whereas phytase supplementation lowered liver cadmium accumulation. In tendency similar effects were obtained for kidney cadmium accumulation.

6-Phytase↗
PubMed1995

Evaluation of Sanofi Diagnostics Pasteur Chlamydia Microplate EIA shortened assay and comparison with cell culture and Syva Chlamydia MicroTrak II EIA in high- and low-risk populations.

Seven hundred thirty-two female urogenital samples were collected for Chlamydia trachomatis testing by both the Sanofi Diagnostics Pasteur (Chaska, Minn.) Chlamydia Microplate EIA by the shortened protocol and the Syva (San Jose, Calif.) MicroTrak II EIA, and the results were compared with those obtained by cell culture. For the analysis of samples from female patients, the patients were divided into high- and low-risk categories. An additional 121 male urethral samples were collected and tested by the Sanofi Microplate EIA and cell culture; for the analysis of samples from male patients, the patients were divided into asymptomatic and symptomatic categories. All specimens positive by enzyme immunoassay (EIA) were confirmed by a blocking assay following the respective manufacturer's instructions. Specimens negative by EIA that fell within a gray zone 30% below the cutoff and negative cultures with one or more corresponding positive EIA results were tested further by cytocentrifugation and direct immunofluorescent assay. The overall sensitivity, specificity, positive predictive value, and negative predictive value for Syva versus culture were 94, 98.8, 85.5 and 99.6%, respectively. After resolution, the results were 94.5, 99.6, 94.5, and 99.6%, respectively. The parallel results for the Sanofi Microplate EIA versus culture were 94.0, 98.7, and 83.9, and 99.6%, respectively, and after being resolved, the results were 94.9, 100, 100, and 99.6%, respectively. In the small male population tested, the resolved results of the Sanofi Microplate EIA versus culture demonstrated sensitivity, specificity, positive predictive value, and negative predictive value of 100, 100, 100, and 100%, respectively. The present study demonstrated that the Sanofi Microplate EIA shortened protocol is highly sensitive and specific in comparison with cell culture and the Syva MicroTrak II EIA.

Age Factors↗
PubMed1995

Interaction of sulfhydryl reactive reagents with components involved in (1,3)-beta-glucan synthesis from Candida albicans.

Glucan synthesis was sensitive to several sulfhydryl reacting compounds: mercurials, reversible disulfides, and an alkylating sulfhydryl reagent (IC50 3-45 microM). Thiol groups associated with glucan synthesis were hydrophilic in nature, since both hydrophilic and hydrophobic reagents were active. Glucan synthase complex consists of at least two components: a peripheral GTP-binding protein that can be solubilized with detergents (supernatant) and the catalytic membrane-bound component (pellet). A rapid separation technique was developed to study sulfhydryl interactions with the complex. The GTP-binding protein was solubilized with 0.6% 3-((3-cholamidopropyl)dimethylammonio)-1-propane sulfonate from isolated microsomes of Candida albicans cells grown at either 10 or 30 degrees C. The residual membranous fraction contained the core catalytic moiety of glucan synthase. Both fractions were devoid of glucan synthase activity until they were reconstituted by mixing the two fractions together. In reconstitution experiments, the pellet lost almost 50% activity when preincubated with 2.5 microM N-ethylmaleimide and combined with an untreated supernatant whereas only 10% activity was lost when the supernatant was treated with N-ethylmaleimide. The catalytic active site of glucan synthase was not protected with UDP-Glc when preincubated with 10 microM N-ethylmaleimide but the GTP-binding fraction was partially protected with GTP gamma S.

Candida albicans↗
PubMed1995

Effect of phytic acid and microbial phytase on Cd accumulation, Zn status, and apparent absorption of Ca, P, Mg, Fe, Zn, Cu, and Mn in growing rats.

Three groups of individually housed albino rats (n = 6, initial average weight = 47 g) were fed diets based on egg white and cornstarch (basal diet 8 g Ca, 5.2 g P, 0.76 g Mg, 100 mg Zn, 100 mg Fe, 50 mg Mn, 7 mg Cu, and 5 mg Cd per kilogram diet) over a 4-week period. Group I (controls) was fed the basal diet free of phytic acid (PA) and microbial phytase. In groups II and III cornstarch was replaced by 0.5% PA from NaPA (molar PA/Zn ratio approximately 5). In group III, 2,000 U of microbial phytase from Aspergillus niger per kilogram diet was added. Live weight gain, zinc status (zinc in plasma, femur, liver, and testes; activity of the plasma alkaline phosphatase), and apparent absorption of zinc, iron, copper, and manganese remained unchanged by the different dietary treatments. The apparent phosphorus absorption was highest in the phytase group. PA decreased and microbial phytase improved the apparent absorption of calcium and magnesium. Liver cadmium concentration, total liver and kidney cadmium content, as well as fractional liver and kidney cadmium accumulation in rats fed the diet containing PA were significantly higher than those in the controls. Phytase supplementation lowered liver and kidney cadmium accumulation. Differences in calcium and magnesium bioavailability due to PA and microbial phytase may be one factor in the alteration of tissue cadmium accumulation.

6-Phytase↗