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Biomedical subjects

A Knecht

Publications and source records attributed to A Knecht.

At least 19 recordsLinked to original sources
PubMed2005

[Resurfacing arthroplasty of the hip].

Currently, an increase in resurfacing arthroplasty in the treatment of hip osteoarthritis--especially in young adults--can be observed. New bearing technologies (mainly metal-on-metal surfaces) show better tribologic results than historical designs (e.g. the Wagner cup). At present, it is unclear whether these modifications and a definitively low dislocation rate--due to the large head diameter--can be supported by further good clinical results. The quantity as well as the quality of the available investigations prevents a definite opinion at the moment. Appropriate clinical studies with documented radiographic follow-up are necessary to compare the outcome of these new implants with standard techniques.

Arthroplasty, Replacement, Hip↗
PubMed2004

[Hip resurfacing arthroplasty].

In comparison to stemmed total hip replacements, hip resurfacing offers advantages especially in joint stability and amount of femoral bone resection. After the poor results achieved with this concept that were mainly caused by failure of the materials used, reintroduction of the metal-on-metal bearing initiated a renaissance. This bearing, the cementless cup, and the improved surgical technique led to better short- to medium-term results. Revision and complication rates are now comparable to conventional total hip replacements. The functional capacity of the method is higher. Because long-term results are not available, however, questions remain, for instance, the consequences of the higher metal ion serum concentrations or the impossibility of changing the inlay when femoral revision becomes necessary.

Adolescent↗
PubMed2000

Secondary prevention with antioxidants of cardiovascular disease in endstage renal disease (SPACE): randomised placebo-controlled trial.

BACKGROUND: Excess cardiovascular mortality has been documented in chronic haemodialysis patients. Oxidative stress is greater in haemodialysis patients with prevalent cardiovascular disease than in those without, suggesting a role for oxidative stress in excess cardiovascular disease in haemodialysis. We investigated the effect of high-dose vitamin E supplementation on cardiovascular disease outcomes in haemodialysis patients with pre-existing cardiovascular disease. METHODS: Haemodialysis patients with pre-existing cardiovascular disease (n=196) aged 40-75 years at baseline from six dialysis centres were enrolled and randomised to receive 800 IU/day vitamin E or matching placebo. Patients were followed for a median 519 days. The primary endpoint was a composite variable consisting of: myocardial infarction (fatal and non-fatal), ischaemic stroke, peripheral vascular disease (excluding the arteriovenous fistula), and unstable angina. Secondary outcomes included each of the component outcomes, total mortality, and cardiovascular-disease mortality. FINDINGS: A total of 15 (16%) of the 97 patients assigned to vitamin E and 33 (33%) of the 99 patients assigned to placebo had a primary endpoint (relative risk 0.46 [95% CI 0.27-0.78], p=0.014). Five (5.1%) patients assigned to vitamin E and 17 (17.2%) patients assigned to placebo had myocardial infarction (0.3 [0.11-0.78], p=0.016). No significant differences in other secondary endpoints, cardiovascular disease, or total mortality were detected. INTERPRETATION: In haemodialysis patients with prevalent cardiovascular disease, supplementation with 800 IU/day vitamin E reduces composite cardiovascular disease endpoints and myocardial infarction.

Aged↗
PubMed1996

Successful treatment of secondary hyperparathyroidism in hemodialysis patients with oral pulse 1-alpha-hydroxy-cholecalciferol therapy.

We have used high-dose oral pulse therapy with 1 alpha-hydroxycholecalciferol (1 alpha-OH-D3) to treat 40 hemodialysis patients suffering form secondary hyperparathyroidism. Forty patients with intact parathyroid hormone (PTH) levels of > 150 pg/ml were treated with 4 micrograms oral 1 alpha-OH-D3 twice weekly for 1 year. The mean PTH level was 515 +/- 50 pg/ml prior to treatment, which fell to 191 +/- 42 pg/ml after 6 months of treatment (p < 0.00001), and to 164 +/- 39 pg/ml after 12 months of treatment. Patients with very high PTH levels (> 800 pg/ml) suppressed less well than patients with lower levels (150-300 pg/ml). The therapeutic end point of PTH < 100 pg/ml was achieved in 23 patients (58%). The main side effect of the treatment was hypercalcemia, but this was symptomatic in only 3 patients, all above the age of 70 years. In summary, oral high-dose pulse therapy with 1 alpha-OH-D3 was highly effective in suppressing PTH levels in hyperparathyroid hemodialysis patients, and side effects were relatively few.

Administration, Oral↗
PubMed1993

Glycerol induced ARF in rats is mediated by tumor necrosis factor-alpha.

Glycerol-induced acute renal failure (ARF) in rats is a model of acute trauma in which intra-muscular injection of 50% glycerol causes rapid myoglobinuria, oliguria, and a rapid reduction in glomerular filtration rate. We found that plasma tumor necrosis factor-alpha (TNF-alpha) is rapidly induced in glycerol injected rats. It can be detected in some animals as early as 30 minutes post-injection, peaks at one hour (range: 4 to 32 U/ml) with no significant difference between blood from renal vein and vena cava, and decreases by three hours. None was detected in control saline injected rats (P < 0.001). Four out of five rats infused with neutralizing anti-TNF-alpha antiserum (200 microliters/300 g body wt) immediately prior to glycerol injection had significantly protected kidney function (P = 0.001). In these rats, plasma urea (104.8 +/- 58.9 mg%) and creatinine (1.16 +/- 0.38 mg%) were lower and creatinine clearance higher (0.34 +/- 011 ml/min) than in glycerol injected animals pretreated with normal serum (291.8 +/- 41.8 mg%, 3.15 +/- 0.74 mg%, and 0.03 +/- 0.03 ml/min, respectively) or animals injected with glycerol alone (302.6 +/- 76.8 mg%, 3.45 +/- 0.97 mg%, and 0.03 +/- 0.03 ml/min, respectively). These results imply a direct role for TNF-alpha in pathogenesis of glycerol induced ARF in rats.

Acute Kidney Injury↗
PubMed1991

Inhalation therapy: alternative systems--an overview.

Three possibilities exist, in principle, to apply medication by inhalation: (1) Inhalation from Pressurized Metered Dose Inhalers (2) Direct Inhalation of Dry Powder (3) Inhalation of Nebulized Aqueous Solutions. Chlorofluorocarbons that are necessary for pressurized metered dose inhalers have unwanted environmental properties. Therefore, alternative gases are being developed (HFA-134a and HFA 227) on the premise that pressurized metered dose aerosols in airways therapy have distinct advantages which are reflected in the high acceptance and application of these MDIs worldwide. Dry powder inhalation requires sophisticated devices to provide for exact dosing. For nebulizers the major problem was their size and consequently their restricted use. Multi-dose pocket-size systems are on the market for (1) and (2). For nebulization such a system is currently being introduced. A critical comparison of benefits and disadvantages of the existing drug delivery systems to the airways leads to the conclusion that all three modes will remain essential to cover the therapeutic needs for a wide variety of drugs and patient populations.

Administration, Inhalation↗
PubMed1991

Fibroblasts of rabbit kidney in culture. I. Characterization and identification of cell-specific markers.

There is currently no information available as to whether different renal fibroblast subpopulation can be identified and whether they show differences in functional properties. We therefore compared the growth characteristics of interstitial fibroblasts derived from the rabbit renal cortex and inner medulla (papilla) and sought cell-specific markers for the two populations of cells. Analyses of the population dynamics revealed that the mitotic lifespan of papillary fibroblasts (PF) is approximately 50% longer than that of cortical fibroblasts (CF), with the former going through 20 cumulative population doublings (CPD) before transition into terminally differentiated postmitotic cells compared with 9 CPD in CF. PF and CF populations contained three types of mitotically active cells (MFI, MFII, MFIII) and three types of postmitotic cells (PMFIV, PMFV, PMFVI) differentiating along a terminal cell lineage from MFI through PMFVI. In both PF and CF cultures the percent of MF-type cells decreased and the percent of postmitotic cells increased with successive doublings. Two-dimensional polyacrylamide gel electrophoresis of uniform clonal populations of MFIII-type cells revealed two specific proteins for PF-MFIII-type cells, pf1 and pf2, and three specific proteins for CF-MFIII-type cells, cf1, cf2, and cf3. Additionally, a monoclonal antibody was raised that does not recognize CF in culture, but reacts strongly with PF. These studies demonstrate that rabbit renal PF have a pattern of growth in vitro that is distinct from that of CF and that they can be positively identified by specific immunological and protein markers in vitro.

Animals↗
PubMed1991

Fibroblasts of rabbit kidney in culture. II. Paracrine stimulation of papillary fibroblasts by PDGF.

To examine the role of tubulointerstitial cell interaction in the regulation of fibroblast growth, fibroblasts from the rabbit renal cortex (CF) and papilla (PF) were cocultured with epithelial cells from the same tissue location. Inner medullary collecting duct epithelial cells (IMCDE) or IMCDE-conditioned medium stimulated DNA synthesis in PF, whereas proximal tubule epithelium (PTE) had no effect on the proliferation of CF. PF and CF showed a similar mitogenic response to exogenous epidermal growth factor and insulin-like growth factor 1 (IGF-I). Transforming growth factor-beta 1 inhibited growth of both cell types, and basic fibroblast growth factor (bFGF) had no effect on proliferation of either cell type. In contrast, platelet-derived growth factor (PDGF) was a potent mitogen for PF but was only weakly mitogenic for CF. Both CF and PF expressed a similar number of a single-affinity class of PDGF receptors (Kd, 2-4 x 10(-10) M). Assay for growth factor activity in conditioned medium from IMCDE and PTE showed that only IMCDE produced detectable PDGF. IMCDE-stimulated proliferation of PF was partially blocked by an antibody to PDGF, whereas antibodies to IGF-I had no neutralizing effect. The data suggest a role for PDGF in the regulation of interstitial fibroblast proliferation by IMCDE in the renal papilla. This paracrine system may be important in the pathogenesis of some forms of interstitial fibrosis of the kidney.

Animals↗
PubMed1990

Levels and correlates of blood pressure in recent and earlier Ethiopian immigrants to Israel.

Blood pressure (BP) and anthropometric data were collected on 483 recent immigrants from Ethiopia to Israel, and on 171 adults and 100 adolescent boarding school students who had immigrated two to three years earlier. Comparison of samples within the Ethiopian groups, and between new and early Ethiopian immigrants with Israel and resident Israelis revealed the following: Systolic and diastolic BP were considerably lower in recent immigrants of both sexes than among counterparts residing in Israel for two to three years. The latter group significantly approached, but did not reach, the BP levels of veteran Israelis. A similar comparison of 100 immigrant Ethiopian boarding school children with an Israeli high school population revealed apparently larger differences among the boys than the girls, whose BP was 'adapted' to a greater degree. Differences in relative weight paralleled those identified for BP, with the Quetelet index (QI) progressively higher when comparing new immigrants with earlier ones, and with persons who have lived in Israel for a longer period. Whether the weight differences provide a complete explanation for BP changes cannot be definitely stated, pending prospective data on weight and BP changes. Correlations of BP with anthropometric parameters and pulse rate indicated that weight rather than QI was the stronger correlate of BP in adults, whereas weight and height, but not QI, correlated with BP in adolescent boys. QI correlated with BP in adolescent, apparently sexually mature girls, but not in boys.

Adolescent↗
PubMed1989

Blood pressure in Ethiopian immigrants in Israel: comparison with resident Israelis.

Blood pressure was examined in 483 Ethiopian immigrants a few weeks after their arrival in Israel. The results were compared with those from a group of 171 Ethiopian immigrants who came to Israel 2-3 years earlier. Mean blood pressure was significantly higher in the veteran immigrants, whose weight was also greater. Both groups had lower blood pressure than the resident Israeli population.

Adolescent↗
PubMed1988

Castleman's disease. An uncommon computed tomographic feature.

A case of localized intrathoracic Castleman tumor demonstrated, on CT scan, calcifications in a circumferential distribution. The prevalence of calcifications in Castleman's disease and the differential diagnosis of the above unusual CT findings are discussed.

Adult↗
PubMed1985

Uncommon presentation of pheochromocytoma: case studies.

Twelve patients with pheochromocytoma have shown unusual clinical and laboratory presentation. These include three patients with cardiac manifestations (sick sinus syndrome, obstructive cardiomyopathy and ischemic ECG changes). Two patients with gastrointestinal problems (acute abdomen due to ischemic bowel and constipation). One child with sudden blindness and one, non diabetic patient with polyuria. Laboratory findings included four patients with diabetes mellitus, four patients with hypercalcemia two of them with concomitant hyperreninemia and one patient with hypokalemia. Awareness of the illness leads to the discovery of unusual cases and even a most severely sick patient can make a complete recovery.

Adolescent↗
PubMed1985

Enalapril in the treatment of renovascular hypertension.

Enalapril, an angiotensin converting enzyme (ACE) inhibitor, was given to 12 patients with renovascular hypertension: To five of them as a single drug after discontinuing other medications, and to seven patients as a substitute for one of their previous medications. The drug proved effective in controlling hypertension in all patients. Flushing and palpitations occurred in two of them, one of whom also showed a rise in creatinine and mild hyperkalemia. Two patients who had developed side effects while on captopril (renal deterioration in one, and severe rash in the other) tolerated enalapril well. Enalapril effectively reduced the blood pressure in the one patient with bilateral renal artery stenosis without causing renal failure.

Adult↗