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Biomedical subjects

A Kramer

Publications and source records attributed to A Kramer.

At least 73 records · Page 4Linked to original sources
PubMed2001

Regulation of daily locomotor activity and sleep by hypothalamic EGF receptor signaling.

The circadian clock in the suprachiasmatic nucleus (SCN) is thought to drive daily rhythms of behavior by secreting factors that act locally within the hypothalamus. In a systematic screen, we identified transforming growth factor-alpha (TGF-alpha) as a likely SCN inhibitor of locomotion. TGF-alpha is expressed rhythmically in the SCN, and when infused into the third ventricle it reversibly inhibited locomotor activity and disrupted circadian sleep-wake cycles. These actions are mediated by epidermal growth factor (EGF) receptors on neurons in the hypothalamic subparaventricular zone. Mice with a hypomorphic EGF receptor mutation exhibited excessive daytime locomotor activity and failed to suppress activity when exposed to light. These results implicate EGF receptor signaling in the daily control of locomotor activity, and identify a neural circuit in the hypothalamus that likely mediates the regulation of behavior both by the SCN and the retina.

Animals↗
PubMed2001

Loss of caspase-1 and caspase-3 protein expression in human prostate cancer.

Activation of the caspase cascade is involved in the execution of apoptosis in a variety of cellular systems. Recent studies demonstrated that caspase-1 activation was required for human prostate cancer cells to undergo apoptosis in response to transforming growth factor-beta (Y. Guo and N. Kyprianou, Cancer Res., 59: 1366-1371, 1999). In the present study, to identify the significance of caspases in prostate cancer progression, we examined the expression of three key caspases, caspase-1, caspase-3, and caspase-9, in normal and malignant human prostates. Caspase-1, -3, and -9 expression was examined at the mRNA and the protein level in a series of human normal and malignant prostate specimens. No significant differences were observed in the mRNA expression in prostatic tumors relative to the normal gland for any of the three caspases. Immunohistochemical analysis revealed that the pattern of protein expression and distribution was uniformly homogeneous in the normal prostate, with the epithelial cells exhibiting a diffuse cytoplasmic staining for caspase-1 and caspase-3. Significantly, the majority of primary prostate cancer specimens (80%) had total lack of caspase-1 immunoreactivity, whereas the remaining showed a significantly reduced expression compared with the normal prostate (P < 0.05). Caspase-3 expression was also reduced in moderately and poorly differentiated prostatic tumors compared with well-differentiated prostate adenocarcinomas and the normal prostate (P < 0.05). No significant correlation was found between the apoptotic index or Gleason grade and the pattern of caspase protein expression in the primary prostatic tumors analyzed. Western blot analysis revealed constitutive expression of the proenzyme forms of caspase-1, -3, and -9 in the human prostate cancer cell lines PC-3, DU-145, TSU-Pr1m and LNCaP, but caspase-1 expression was low in the less tumorigenic cell lines, DU-145 and LNCaP. These findings implicate the loss of caspase-1 protein as a potential step in the loss of apoptotic control during prostate tumorigenesis. This study suggests that the pattern of caspase-1 and -3 expression in prostatic tumors may have prognostic significance in disease progression.

Blotting, Western↗
PubMed2001

[Antimicrobial decontamination of corneal donor material: infection prevention and quality assurance].

BACKGROUND: Microbiological examinations in eye banks have found an increased contamination rate in preservation media. We studied the effect of prolonged submersion time for decontaminating donor globes. MATERIALS AND METHODS: We retrospectively analyzed the primary contamination of conjunctival smears in 76 cornea donors. The submersion time of donor eyes in PVP iodine solution before preparation was prolonged from 1 min to 5 min, and the contamination rate of storage vessels was compared. RESULTS: In 13 of the 76 conjunctival smears we found no contamination. Before prolonging submersion time, the preservation medium was contaminated in 15 cases, but after 5 min no contamination was observed. CONCLUSION: Prolonging the submersion time of donor globes from 1 to 5 min was effective. The model presented here provides guidelines for existing eye banks as well as for those yet to be established.

Antisepsis↗
PubMed2001

Effect of age on outcome of bilateral skeletonized internal thoracic artery grafting.

BACKGROUND: Elderly patients are considered to be at higher risk for coronary artery bypass grafting. Surgical techniques of arterial myocardial revascularization without vein grafts were primarily reserved for the young. This report evaluates the impact of age on the outcome of 634 consecutive patients who underwent double skeletonized internal thoracic artery grafting between April 1996 and December 1997. METHODS: Patients were stratified into five age groups: One hundred ninety-six were less than 60 years of age, 98 between 60 and 65 years, 132 between 65 and 70 years, 116 between 70 and 75 years, and 92 were older than 75 years. The groups did not differ with regard to preoperative risk factors. RESULTS: Hospital mortality was 2.5% (n = 16). Mortality of urgent and elective operations was 1.6%, and that of emergency operations was 9.7% (p < 0.001). There were 7 (1.1%) myocardial infarctions, 9 strokes (1.4%), and 10 deep sternal wound infections (1.6%). Using the Mantel-Haenszel test, there was no relation between age and hospital mortality, myocardial infarctions, strokes, or sternal infections. A correlation was found between advanced age and early unfavorable events (6.7%, 7.2%, 12.9%, 15.5%, and 15.2% in corresponding age groups, p < 0.003), and late mortality (0.6%, 1%, 1.5%, 4.3%, and 9.8%, respectively, p < 0.01). However, early return of angina was lower (2.6%, 1%, 0.8%, 0.9%, and 0%, p < 0.06). CONCLUSIONS: This retrospective, nonrandomized study suggests that older age is not a risk factor for operative mortality in patients undergoing coronary artery bypass grafting with double skeletonized internal thoracic arteries. Apart from avoiding morbidity associated with leg incisions, older patients showed an interesting trend toward lower rates of angina return. Older patients, however, sustained increased perioperative morbidity and late mortality rates.

Actuarial Analysis↗
PubMed2001

Arterial myocardial revascularization with in situ crossover right internal thoracic artery to left anterior descending artery.

BACKGROUND: The extra length obtained by skeletonizing the internal thoracic arteries (ITAs) enables versatile use of in situ bilateral ITAs for coronary artery bypass grafting, as the longer skeletonized right ITA more easily reaches the anastomotic site on the left anterior descending coronary artery. METHODS: Between April 1996 and November 1999, 365 consecutive patients underwent revascularization with bilateral in situ ITAs (29% of 1,250 grafting procedures performed with both ITAs in our department during this period). The right ITA was routed anterior to the aorta to graft the left anterior descending coronary artery, and the in situ left ITA was used to graft circumflex branches. Right coronary artery branches were grafted with right gastroepiploic artery or saphenous vein graft. The right ITA crossed the midline above the aorta at the most cranial point to avoid damage in case of a repeat sternotomy in the future. RESULTS: The operative mortality rate was 2.2% (8 patients). Postoperative morbidity included seven strokes (1.9%), eight sternal wound infections (2.2%), and four perioperative myocardial infarctions (1.1%). Follow-up (6 to 49 months) of 97% of hospital survivors showed a return of angina in 3%. Postoperative coronary angiography (22 patients) revealed a 95% patency rate of both ITAs. One-year and 4-year survival rates (Kaplan-Meier) were 95% and 92.4%, respectively. Important predictors of an early unfavorable event were chronic obstructive pulmonary disease, old age (> or = 70 years), emergency operation, and diabetes. Chronic obstructive pulmonary disease was the only independent predictor of sternal wound infection (odds ratio, 15; 95% confidence interval, 2.8 to 80). It also predicted decreased late survival (hazard ratio, 8.3; 95% confidence interval, 3 to 21.5). CONCLUSIONS: With skeletonized dissection of ITAs, the right ITA easily reaches the left anterior descending coronary artery for left-sided arterial revascularization with in situ bilateral ITAs. This procedure is safe, but we recommend avoiding its use in patients with chronic obstructive pulmonary disease.

Aged↗
PubMed2001

Assessment of the activity of antiperspirants added to surgical hand disinfectants: methodological aspects and first observations.

Due to the risk of sensitization caused by glove powder, the use of unpowdered latex gloves is increasing. These unpowdered gloves need a special inner-surface layer which makes it easier for the applicant to put the glove on the hand and to remove it again. However, many users report difficulties with removing the gloves because of sweat production within the glove. Therefore, a method has been developed to evaluate the efficacy of antiperspirants which may be added either to the inner-surface layer of the glove or to hand disinfectants or to skin-care products used before the gloves are put on. The paper describes various trials to optimize this method.

1-Propanol↗
PubMed2001

Interaction between paracrine tumor necrosis factor-alpha and paracrine angiotensin II during myocardial ischemia.

OBJECTIVES: The purpose of this study was to explore interactions between paracrine angiotensin II (Ang-II) and tumor necrosis factor-alpha (TNF-alpha) during myocardial ischemia. BACKGROUND: Ischemic myocardium releases significant amounts of TNF-alpha. This paracrine release correlated with postischemic myocardial injury. Other studies showed myocardial protection obtained by the use of angiotensin-converting enzyme inhibitors (i.e., captopril) and the Ang-II type 1 receptor antagonist losartan after ischemia. The possibility that these agents decrease TNF-alpha synthesis has not yet been investigated. METHODS: Using the modified Langendorff model, isolated rat hearts underwent either 90 min of nonischemic perfusion (control group) or 1 h of global cardioplegic ischemia. In both groups, either captopril (360 micromol/liter) or losartan (182.2 micromol/liter) was added before ischemia. The hearts were assayed for messenger ribonucleic acid (mRNA) expression and effluent TNF-alpha levels. In addition, cardiac myocytes were incubated in cell culture with Ang-II. RESULTS: After ischemia, TNF-alpha mRNA expression intensified from 0.63 +/- 0.06 (control group) to 0.92 +/- 0.12 (p < 0.03), and effluent TNF-alpha levels were 711 +/- 154 pg/ml. The TNF-alpha mRNA expression declined to 0.46 +/- 0.07 (p < 0.01) and 0.65 +/- 0.08 (p < 0.02) in captopril- and losartan-treated hearts, respectively. Effluent TNF-alpha was below detectable levels. Concentrations of TNF-alpha in supernatants of incubated cardiac myocytes treated with 10 and 50 nmol/liter of Ang-II were 206.0 +/- 47.0 pg/ml and 810 +/- 130 pg/ml, respectively (p < 0.004). When pretreated with 700 micromol/liter of losartan, TNF-alpha was below detectable levels. CONCLUSIONS: This study presents an original explanation for previously reported myocardial protection after ischemia, obtained by the use of captopril and losartan. These drugs reduce TNF-alpha synthesis, providing strong evidence of active interactions between paracrine TNF-alpha and Ang-II in the evolution of the ischemic cascade.

Angiotensin II↗
PubMed2001

Impact of cardiac resynchronization therapy using hemodynamically optimized pacing on left ventricular remodeling in patients with congestive heart failure and ventricular conduction disturbances.

OBJECTIVES: We sought to investigate the impact of six months of cardiac resynchronization therapy (CRT) on echocardiographic variables of left ventricular (LV) function. BACKGROUND: Cardiac resynchronization therapy has recently been introduced as a new therapeutic modality in patients with advanced heart failure (HF) and conduction abnormalities. However, most studies have only investigated the early hemodynamic effects of CRT. METHODS: Twenty-five patients (12 women and 13 men; 59.8 +/- 5.1 years old) with advanced HF caused by ischemic (n = 7) or idiopathic dilated cardiomyopathy (n = 18) and a prolonged QRS complex were analyzed. All patients underwent early hemodynamic testing with a randomized testing protocol; echocardiographic measurements were compared before implantation and after six months of CRT. RESULTS: Left ventricular end-diastolic and end-systolic diameters (LVEDD and LVESD, respectively) were significantly reduced after six months (LVEDD from 71 +/- 10 to 68 +/- 11 mm, p = 0.027; LVESD from 63 +/- 11 to 58 +/- 11 mm, p = 0.007), as were LV end-diastolic and end-systolic volumes (LVEDV from 253 +/- 83 to 227 +/- 112 ml, p = 0.017; LVESV from 202 +/- 79 to 174 +/- 101 ml, p = 0.009). Ejection fraction was significantly increased (from 22 +/- 7% to 26 +/- 9%, p = 0.03). "Nonresponders," with regard to LV volume reduction, had significantly higher baseline LVEDV, compared with "responders" (351 +/- 52 vs. 234 +/- 74 ml, p = 0.018). Overall, there was only mild mitral regurgitation at baseline, with a minor reduction by semiquantitative analysis. The results of early hemodynamic testing did not predict the volume response. CONCLUSIONS: Cardiac resynchronization therapy may lead to a reduction in LV volumes in patients with advanced HF and conduction disturbances. Volume nonresponders have significantly higher baseline LVEDV.

Aged↗
PubMed2001

Vasoactive response of different parts of human internal thoracic artery to isosorbide-dinitrate and nitroglycerin: an in-vitro study.

OBJECTIVE: The left internal thoracic artery (LITA) is the most important graft for coronary artery bypass grafting (CABG). Its distal region is, however, prone to vasospasm. The effect of nitroglycerin (NTG) and isosorbide-dinitrate (ISDN) on different segments of this region was studied. METHODS: Rings of three segments of the LITA were studied: 6-9 mm proximal to the bifurcation (part A); 1-3 mm proximal to the bifurcation (part B); and 3-6 mm distal to the bifurcation (part C). After baseline, maximal contraction of the rings was achieved using 60 mmol/l of KCl, they were exposed to increasing doses of ISDN and NTG (10-100 microg/ml), and dose-response curves were recorded. RESULTS: The contractile response of part A to KCl was significantly lower than that of parts B and C (1.87+/-0.25 versus 4.05+/-0.39 and 7.64+/-0.54 g, respectively; P<0.001). Both nitrates inhibited the contractile response in a concentration-dependent manner. The relaxing effects of both nitrates on part A was most pronounced (P<0.01), with the effect of ISDN being higher than that of NTG (P<0.01). CONCLUSIONS: The region 6-9 mm proximal to the LITA bifurcation is less prone to vasospasm, and has greater relaxation responses to ISDN and NTG than the more vasospastic distal parts of the LITA. We recommend avoiding the use of the very distal part of this artery during CABG, and to use high doses of ISDN rather than NTG as an anti-spastic measure.

Analysis of Variance↗
PubMed2001

Composite arterial grafting with double skeletonized internal thoracic arteries.

OBJECTIVES: Composite arterial grafting is a surgical technique for arterial myocardial revascularization, in which free arterial conduits are proximally anastomosed end-to-side to an intact internal thoracic artery (ITA). This report describes technical aspects and results of composite grafting using bilateral skeletonized ITAs. METHODS: From April 1996 to February 1999, 1057 patients underwent coronary artery bypass grafting (CABG) using bilateral skeletonized internal thoracic arteries. In 600 of them (57%), composite arterial grafting was performed. There were 452 men and 148 women. The mean age was 69 +/- 7 years. Two-hundred and six patients (34%) were diabetics, 84 (14%) had severe left ventricular dysfunction (ejection fraction of < 35%), and 26 (4.3%) underwent emergency operations. In 574 patients, the right ITA was used as a free graft connected to the in-situ left ITA. In 26, the free left ITA was attached to the in-situ right ITA, and in 38, mini-composite grafts (free distal left ITA on the left ITA, or free distal right ITA on the right ITA) were constructed. The average number of grafts was 3.0/patient (range, 2--6). RESULTS: The operative mortality was 2.8% (n = 17), and there were ten (1.7%), deep sternal wound infections. The mean follow-up was 25 months (range, 14--36 months). The 3-year survival was 92.5%. Ninety-seven percent of the surviving patients were angina-free. CONCLUSIONS: We currently perform this surgery routinely in most patients referred for CABG, and regard bilateral skeletonized internal thoracic arteries as the most appropriate arterial conduits for the composite technique.

Adult↗
PubMed2001

Effects of SCN-/H2O2 combinations in dentifrices on plaque and gingivitis.

OBJECTIVES: A 10-week, double-blind, placebo-controlled clinical study on 140 male subjects was conducted to determine the effect on plaque and gingivitis of 5 dentifrices containing various thiocyanate (SCN-)/hydrogen peroxide (H2O2) combinations. MATERIALS AND METHODS: The dentifrices consisted of a gel base without any detergents or abrasives (placebo, group A) to which SCN- and/or H2O2 were added as follows: 0.1% SCN- (group B), 0.5% SCN- (group C), 0.1% SCN-/0.1% H2O2 (group D), 0.5% SCN-/0.1% H2O2 (group E) and 0.1% H2O2 (group F). A baseline examination was performed in which the Silness and Löe Plaque Index (PI), the Mühlemann and Son Sulcus Bleeding Index (SBI), and the amount of gingival crevicular fluid (GCF) were recorded using the Periotron 6,000 on teeth 16, 12, 24, 36, 32, and 44. The subjects were randomly assigned to either the placebo group (n = 40) or one of the test groups (n = 20) and used their respective dentifrices over a period of 8 weeks. Finally, each group used the placebo for another 2 weeks (wash-out). Re-examinations were performed after 1, 4, and 8 weeks and the 2-week wash-out period employing the clinical parameters used at baseline. Intragroup changes were analyzed with the Wilcoxon signed-ranks test, using the baseline and wash-out points as references. The Mann-Whitney U test was used for comparisons between the treatment groups and the placebo group. RESULTS: At the 8-week examination, the plaque index in group E (p = 0.017) and group F (p = 0.032) was lower than in the placebo group. The Sulcus Bleeding Index in group F after 1 week was increased (p = 0.023) and the SBI in group E after 8 weeks was reduced (p = 0.047) as compared to the placebo group. CONCLUSION: The results demonstrated that a dentifrice containing 0.5% SCN- and 0.1% H2O2 but no detergents or abrasives inhibited plaque and decreased gingivitis.

Adolescent↗
PubMed2001

Effect of a polyhexamethylene biguanide mouthrinse on bacterial counts and plaque.

OBJECTIVES: For various clinical applications, polyhexamethylene biguanide (PHMB) has been used for many years as an antiseptic in medicine. Little is known, however, of its antibacterial activity in the oral cavity and its ability to inhibit plaque formation. In this study, a 0.04% PHMB mouthrinse (A) was compared with a negative control placebo rinse (10% ethanol, flavour) (B) and 2 positive control chlorhexidine rinses, one of which was a 0.12% aqueous solution (C) and the other a commercially available mouthrinse (Skinsept mucosa) diluted to a chlorhexidine concentration of 0.12% (D). MATERIAL AND METHODS: The study was a double-blind, randomised 4-replicate 4 x 4 Latin square cross-over design. Plaque regrowth was assessed with the Turesky et al. modification of the Quigley and Hein plaque index. The in vivo antibacterial effect was assessed by taking bacterial counts from the tooth surface (smears from the lingual surface of 16) and mucosa (smears from the buccal mucosa) 4 h after the 1st rinse with the preparations on day 1 and prior to the clinical examination on day 5. 16 volunteers participated, and on day 1 of each study period were rendered plaque-free, ceased toothcleaning, and rinsed 2x daily with the allocated mouthrinse. On day 5, plaque was scored and smears were collected according to the protocol. Washout periods were 9 days. Data were analysed using ANOVA with Tukey HSD adjustment for multiple comparisons (significance level alpha=0.05). RESULTS: Mouthrinses A, C, and D were significantly more effective in inhibiting plaque than the placebo (B). Mouthrinse C was significantly better than mouthrinses A and D, while mouthrinses D and A were equally effective in inhibiting plaque. Bacterial count reductions on the tooth surface with mouthrinse C were significantly greater compared to mouthrinse A and the placebo (B). The reduction of bacterial counts on the mucosa with C was significantly greater than with A and B after 4 h and significantly greater than with A, B and D after 5 days. Mouthrinse A reduced bacteria on the mucosa significantly more effectively than the placebo (B) after 4 h and 5 days, while mouthrinse D was more effective than the placebo (B) after 4 h. CONCLUSION: The results indicate that a 0.04% PHMB mouthwash inhibits plaque regrowth and reduces oral bacterial counts, and may be used in preventive applications in the oral cavity.

Adult↗
PubMed2001

Effectiveness of basic clinical skills training programmes: a cross-sectional comparison of four medical schools.

OBJECTIVE: Training in physical diagnostic skills is an important part of undergraduate medical education. The objective of this study was to study the outcome of skills training at four medical schools. CONTEXT: At the time of the study, three schools had a traditional lecture-based curriculum and one school had a problem-based learning curriculum with a longitudinal skills training programme. All schools offer extended exposure to clerkships. METHOD: A cross-sectional study in four medical schools was performed, using a written test of skills that has good correlation with actual student performance. The scores attained from four student groups were compared within and between the four medical schools. A total of 859 volunteer students from the later four years at each medical school participated in the study. RESULTS: The mean scores in the traditional medical schools increased with the start of skill training and the hands-on experience offered during the clerkships. Students from the school with the longitudinal skills training programme and the problem-based learning approach had significantly higher mean scores at the start of the clerkships, and maintained their lead in the subsequent clinical years. CONCLUSIONS: Longitudinal skills training seems to offer the students a superior preparation for clerkships as well as influencing the students' learning abilities during the clerkships. The effect of the problem-based learning approach, also related to the innovative philosophy of the curriculum, could not be accounted for.

Belgium↗
PubMed2001

Transmission of a multiresistant Pseudomonas aeruginosa strain at a German University Hospital.

Over 15 months, 60 patients at a German University Hospital became infected or colonized by a multiresistant Pseudomonas aeruginosa strain, which was isolated from tracheal secretions, blood, urine, venous catheters, ascites and several wounds. Most patients had undergone invasive treatment (surgery, cancer therapy). The genetic relationship of the isolates was investigated by pulsed field gel electrophoresis. The isolates were resistant to beta-lactam antibiotics, including carbapenems and aztreonam, to aminoglycosides and quinolones. The only in vitro susceptibility was to polymyxin B. Extensive sampling was carried out to identify contaminated medical devices, surfaces or media (water, food). Samples were taken from doctors and nursing staff and various treatment procedures were observed for several weeks. The handling of respirators, resuscitation tubes, urine bottles, and bedpans resulted in the contamination of the patients' environment, although most devices were cleaned and disinfected with automatic washer/disinfectors. Several wash basins on the intensive care unit were contaminated, but none of the drinking water samples showed any growth of P. aeruginosa. We recommend the strict use of gloves and strict application of alcoholic hand disinfectants immediately after discarding the gloves. The chain of infection ceased after strict cohort isolation and the subsequent introduction of the specific hygiene regime.

Adult↗