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Biomedical subjects

S Wolf

Publications and source records attributed to S Wolf.

At least 19 recordsLinked to original sources
PubMed1996

Stroke in users of low-dose oral contraceptives.

BACKGROUND: Previous studies have linked the use of oral contraceptive agents to an increased risk of stroke, but those studies have been limited to oral contraceptives containing more estrogen than is now generally used. METHODS: In a population-based, case-control study, we identified fatal and nonfatal strokes in female members of the California Kaiser Permanente Medical Care Program and who were 15 through 44 years of age. Matched controls were randomly selected from female members who had not had strokes. Information about the use of oral contraceptives (essentially limited to low-estrogen preparations) was obtained in interviews. RESULTS: A total of 408 confirmed strokes occurred in a total of 1.1 million women during 3.6 million woman-years of observation. The incidence of stroke was thus 11.3 per 100,000 woman-years. On the basis of data from 295 women with stroke who were interviewed and their controls, the odds ratio for ischemic stroke among current users of oral contraceptives, as compared with former users and women who had never used such drugs, was 1.18 (95 percent confidence interval, 0.54 to 2.59) after adjustment for other risk factors for stroke. The adjusted odds ratio for hemorrhagic stroke was 1.14 (95 percent confidence interval, 0.60 to 2.16). With respect to the risk of hemorrhagic stroke, there was a positive interaction between the current use of oral contraceptives and smoking (odds ratio for women with both these factors, 3.64; 95 percent confidence interval, 0.95 to 13.87). CONCLUSIONS: Stroke is rare among women of childbearing age. Low-estrogen oral-contraceptive preparations do not appear to increase the risk of stroke.

Adolescent↗
PubMed1996

Purification and characterization of cysteine-S-conjugate N-acetyltransferase from pig kidney.

Microsomal cysteine-S-conjugate N-acetyltransferase catalyses the N-acetylation of various S-substituted cysteines in liver and kidney. We describe here the purification and more detailed characterization of this enzyme catalysing the final reaction of mercapturic acid biosynthesis, and thus playing a crucial role in the detoxicating metabolism of many xenobiotics. The solubilization of cysteine-S-conjugate N-acetyltransferase by deoxy-BIGCHAP [N,N'-bis-(3-D-gluconamidopropyl)deoxycholamide] was the prerequisite for partial purification by means of anion-exchange chromatography. The molecular mass of the enzyme was determined by gel filtration. A polyclonal antiserum was raised against the excised protein band from SDS/PAGE and purified antibodies were used for the complete purification of native cysteine-S-conjugate N-acetyltransferase by immuno-affinity chromatography. A dimeric form of the enzyme was sometimes detected on SDS/PAGE, depending on the degree of purification. For further characterization of cysteine-S-conjugate N-acetyltransferase, the stability of catalytic activity, the pH optimum and K(m) values were determined. The inhibitory effects of various agents were tested, revealing a substantial, yet not complete, loss of cysteine-S-conjugate N-acetyltransferase activity after treatment with cysteine proteinase inhibitors or probenecid under various conditions.

Acetyltransferases↗
PubMed1996

Haemorheology in patients with branch retinal vein occlusion with and without risk factors.

PURPOSE: The study was carried out to ascertain the role of blood viscosity in patients with branch retinal vein occlusion (BRVO) with and without risk factors. METHODS: In 292 patients with acute BRVO (mean age 65 +/- 10 years) and 292 controls matched for gender, age, and cardiovascular risk factors, haematocrit, plasma viscosity, erythrocyte aggregation and erythrocyte rigidity were measured. A subgroup analysis in patients with and without risk factors was performed. RESULTS: Haematocrit and plasma viscosity values were significantly higher in BRVO patients than in controls, but erythrocyte rigidity and erythrocyte aggregation did not differ. Subgroup analysis revealed no differences in haematocrit and plasma viscosity values between patients with and those without cardiovascular risk factors. CONCLUSIONS: This study shows increased plasma viscosity and haematocrit values in patients with BRVO which are not associated with the presence of other cardiovascular risk factors. Thus, changes in blood fluidity appear to be important factors in the pathogenesis of BRVO.

Adult↗
PubMed1996

Influence of varying muscle forces on lumbar intradiscal pressure: an in vitro study.

The purposes of this study were to determine the effect of including muscle forces in the experimental loading of the spine on the intradiscal pressure and to determine whether this effect correlates with previously established in vivo data. We modeled the spine muscles as of five distinct groups and isolated the effect of each group on the intradiscal pressure (L4-L5). Seven human lumbosacral spines were tested in pure flexion/extension, right/left lateral bending, and left/right axial rotation moments. Stimulated muscle activity strongly influenced load-pressure characteristics, especially for the multifidus. Without muscle forces active, pressure increased proportionately with increasing moment. With five pairs of symmetrical constant muscle forces active (80 N per pair) the pressure increased more than 200% in neutral position and did not increase with increasing moment. The pressure without muscle forces and without axial preload was 0.12 MPa, which is about the same found by earlier in vivo studies of anesthetized subjects in prone position. With simulated muscle forces, the pressure was 0.39 MPa and in the range found for non-anesthetized subjects. We conclude that simulating muscle forces substantially affects intradiscal pressure.

Adult↗
PubMed1996

Myocardial infarction in users of low-dose oral contraceptives.

OBJECTIVE: To determine the relationship between the use of low-dose (less than 50 micrograms estrogen) oral contraceptives (OC) and myocardial infarction. METHODS: In this population-based case-control study, all incident myocardial infarctions in women, ages 15-44 years who were members of the Kaiser Permanente Medical Care Program, Northern and Southern California regions were ascertained during a 39-month period from 1991 through 1994. For each woman with myocardial infarction, up to three age- and facility-matched controls were chosen at random from female members. Information about OC use (predominantly low-dose preparations) was obtained in face-to-face interviews. RESULTS: There were 187 incident cases of myocardial infarction during 3.6 million woman-years of observation (incidence rate, 5.2 per 100,000 woman-years). The prevalence of several risk factors for myocardial infarction was lower in controls who were current users of OCs than in controls who were noncurrent (past and never) users. The odds ratio for myocardial infarction in current OC users compared with noncurrent users was 1.65 (95% confidence interval 0.45, 6.06) after adjustment for major risk factors and for race and ethnicity, corresponding to an excess risk of less than one case per 100,000 woman-years. The study had 80% power to detect a relative risk of 2.3 (one-sided test, alpha = .05). The odds ratio of myocardial infarction in past OC users was not elevated. CONCLUSION: With respect to myocardial infarction, low-dose oral contraceptives can be used safely by women who lack risk factors for coronary heart disease.

Adolescent↗
PubMed1996

Role of rheologic factors in patients with acute central retinal vein occlusion.

PURPOSE: To assess the rheologic findings in acute central retinal vein occlusion (CRVO) with respect to associated risk factors, the clinical appearance of ischemic or nonischemic CRVO, and to elucidate the etiology of possible changes. METHODS: The authors enrolled 173 patients with acute CRVO (ischemic, 33%; nonischemic, 67%) in this prospective study. One hundred seventy-three patients who were matched for age, sex, and cardiovascular risk factors served as control subjects. All patients underwent testing to determine hematocrit values, plasma viscosity (PV), erythrocyte aggregation (SEA), and erythrocyte rigidity (SER). RESULTS: Hemocrit values and PV were increased significantly (P<0.01) in patients with ischemic and nonischemic CRVO compared with control subjects but did not differ significantly between the two groups. No significant differences were found in SEA and SER values between the clinical subsets of patients with CRVO and when the patients were compared with matched control subjects. Analysis revealed that hemocrit and PV values were (P<0.001) increased significantly independent of associated cardiovascular risk factors. CONCLUSION: These results suggest that increased hemocrit and PV values may be contributing factors in the pathogenesis of CRVO.

Acute Disease↗
PubMed1996

[Risk factors in patients with amaurosis fugax].

BACKGROUND: In the diagnosis of retinal and cerebral vascular occlusion and migraine amaurosis fugax may be an important symptom. To evaluate the relation between cardiovascular diseases and amaurosis fugax we investigated the risk factors in patients with amaurosis fugax. MATERIALS AND METHODS: Twenty-four patients (14 m, 10 f; aged 22 to 84 years; mean: 55 +/- 19 years) with amaurosis fugax were included in this study. All patients underwent a detailed clinical and ophthalmological examination, including video fluorescein angiography shortly after the event. RESULTS: The duration of symptoms ranged from 30 seconds to 30 minutes (median: 3 minutes). Additional acute symptoms were headache in eight patients and tinnitus in one patient. Visual acuity showed no difference between the effected and the fellow eye. Intraocular pressure was normal in all eyes. Video fluorescein angiography revealed normal retinal perfusion times in all cases (arm-retina-time: 12.9 +/- 3.8 s; arteriovenous passage time: 1.8 +/- 0.7 s). Cardiovascular risk factors were present in all patients: 58% of the patients suffered from arterial hypertension, 8% of the patients from diabetes mellitus. Hyperlipidaemia was diagnosed in 17% of the patients, 46% of the patients were smokers. A history of cardiovascular disease (e.g. myocardial infarction, vitium, arrhythmia) was found in 58% of the patients. Cerebrovascular disease was diagnosed in 54% of the patients (migraine: 33%). CONCLUSIONS: The ophthalmologic examination especially the fluorescein angiography revealed no pathologic findings in patients with amaurosis fugax. The risk factor distribution corresponded to data found in patients with retinal artery occlusion.

Adult↗
PubMed1996

[Retinal hemodynamics in diabetic retinopathy before and after laser coagulation].

PATIENTS AND METHODS: By means of video-fluoresce in angiography arm-retina-time (ART) and retinal arteriovenous passage time (AVP) were measured in order to determine the effect of panretinal laser-coagulation on retinal circulation in patients with diabetic retinopathy. 55 patients with either preproliferative (n = 29) or proliferative (n = 26) retinopathy we reexamined before, 3-9 weeks after panretinal laser-coagulation (mean: 848 burns, 0.5 mm diameter), and 0.5-3 years later. RESULTS: The ART of the diabetic patients was in the normal range and showed no differences among the three measuring times. The retinal AVP was significantly prolonged in the three measuring times (nasal and temporal) when compared to normals. Laser-coagulation showed no significant effect on AVP in the temporal branches, whereas in the nasal branches AVP decreased from 2.38 +/- 0.69 s (before laser-coagulation) to 2.11 +/- 0.68 s (3-9 weeks after treatment) and 2.06 +/- 0.67 s (0.5-3 years after treatment) (p < 0.01). In branches with neovascularisation (n = 24) a pronounced decrease of AVP from 2.60 +/- 0.70 s to 1.96 +/- 0.61 s and 2.09 +/- 0.64 s (p < 0.01) was detected. CONCLUSIONS: Thus, laser-coagulation leads to a faster circulation in areas with laser burns within 3-9 weeks post-treatment.

Adult↗
PubMed1996

[Variability of perifoveal microcirculation in healthy probands].

BACKGROUND: Fluorescein angiography with a scanning laser ophthalmoscope allows the assessment of retinal hemodynamics. Fundamental for all interpretations of the evaluated data is the knowledge of the physiological variation. In the present study we examined the variability of dynamic and morphologic retinal blood flow indices in healthy subjects over a period of one year. PATIENTS AND METHODS: In sixteen healthy volunteers aged from 23 to 34 years video-fluorescein angiography was repeated nine times in one year. At each term arm-retina-time, arteriovenous passage time, mean arterial dye velocity and capillary flow velocity were assessed. In addition the perifoveal intercapillary areas and the foveal avascular zone were determined at the first and last examination. RESULTS: Statistical analysis of the evaluated data did not show any significant variation of the mean values during the one year follow-up. Reliability indices between 0.61 and 0.87 underline a stable position of each subject to the other participants at the single terms. CONCLUSION: The present study demonstrates that retinal hemodynamics are stable over a one year follow-up in healthy subjects. There are not significant changes to expect in retinal hemodynamics assesses in healthy subjects in one year under constant conditions. The knowledge of the intra- and interindividual variation of retinal blood flow indices allows a correct interpretation of pathophysiologic and pharmacological changes in retinal macro- and microcirculation.

Adult↗
PubMed1996

Borderline papillary serous tumour of the fallopian tube.

We report a case of borderline papillary serous tumor of the fallopian tube in a 31-year-old woman. The tumor was characterized by the formation of papillary projections with focally prominent epithelial stratification and atypia. The histologic features of the tumor were largely similar to a borderline serous tumor of the ovary. Two years after initial presentation, the patient underwent in vitro fertilization and carried the ensuing pregnancy to term. There is no evidence of disease nearly 6 years after presentation, which suggests that these extremely uncommon tumors can be managed conservatively.

Adult↗
PubMed1996

Comparison of two DNA viruses infecting the marine brown algae Ectocarpus siliculosus and E. fasciculatus.

The marine brown algal genus Ectocarpus contains two species, E. siliculosus and E. fasciculatus. Field populations of both species include plants with infection symptoms caused by DNA viruses. We have established clonal cultures from infected and normal host plants and investigated the properties of the endogenous viruses. Both host species contain virus particles with a hexagonal cross-section and a diameter of ca. 150 nm. The genomes of both virus types consist of double-stranded DNA, approximately 320 kb in size. Restriction digestion with Sfil revealed differences between the two virus genomes. However, PCR experiments suggest that at least one gene, which encodes a major capsid protein, is quite similar in both virus species. In cross-infection experiments the E. siliculosus virus did not initiate an infection cycle in E. fasciculatus. In contrast, the E. fasciculatus virus infected E. siliculosus zoospores. The resulting plants showed aberrant symptoms and produced virus particles which were not infectious. We conclude that the two Ectocarpus species are hosts for different, but closely related viruses.

Capsid↗
PubMed1996

Hyperoxia improves contrast sensitivity in early diabetic retinopathy.

AIM: The cause of vascular and visual pathology in diabetic retinopathy remains unknown. If retinal hypoxia plays a role, then early in the course of diabetes 100% oxygen breathing should normalise both contrast sensitivity and retinal blood flow. METHODS: This hypothesis was tested in 12 diabetic patients with minimal retinopathy who, none the less, exhibited reduced contrast sensitivity (p = 0.003 versus 12 age and sex-matched controls) and prolonged retinal arteriovenous dye transit (p = 0.0001 versus controls). RESULTS: Isocapnic hyperoxia failed to alter contrast sensitivity in controls, while it significantly improved contrast sensitivity in patients (at 12 cpd; p = 0.042) to levels indistinguishable from normal. Individual improvement in contrast sensitivity correlated positively with the severity of the initial defect (r = +0.84, p = 0.0008). Hyperoxia also had haemodynamic effects; it slowed retinal arteriovenous passage of fluorescein dye in controls, but did not further slow this transit time in patients. CONCLUSIONS: These results demonstrate the reversibility of early contrast sensitivity deficits in diabetes mellitus, and support the hypothesis that factors linked to tissue hypoxia initiate both visual and vascular dysfunction in diabetic retinopathy.

Adult↗
PubMed1996

Retinal blood flow indices in patients infected with human immunodeficiency virus.

AIMS/BACKGROUND: Abnormal blood flow dynamics are believed to contribute to the development of retinal microvascular disease in patients infected with human immunodeficiency virus (HIV). In this study, the scanning laser ophthalmoscope (SLO) was used, combined with fluorescein angiography, to measure retinal blood flow indices in HIV seropositive patients. METHODS: Arteriovenous passage time (AVP) and perifoveal capillary blood flow velocity (CFV) were measured in 23 HIV infected patients and 23 control subjects with SLO fluorescein angiography. RESULTS: No significant difference in AVP was found between the two groups. However, CFV was significantly reduced in HIV infected patients (p = 0.013). CONCLUSION: Patients infected with HIV show abnormal haemodynamics at the level of the perifoveal capillaries.

Adult↗
PubMed1996

Retinal hemodynamics during increased intraocular pressure.

The pathogenesis of primary chronic open-angle glaucoma (POAG) remains uncertain. It has been proposed that some of these patients may present with a deficiency in retinal hemodynamic autoregulation. It is also thought that visual field loss in POAG could be related to poor retinal perfusion. The present study was undertaken to evaluate the capacity of retinal autoregulation to maintain constant retinal circulation despite an acute rise in intraocular pressure (IOP). A total of 22 healthy subjects were recruited to this study. Retinal hemodynamics were assessed by digital video fluorescein angiograms using a scanning laser ophthalmoscope at normal (13.8 +/- 1.5 mmHg) and increased IOP (33.8 +/- 3.4 mmHg). Suction cups were used for raising the IOPs. The angiograms were performed at baseline and after 1 min of increased IOP. To quantify retinal hemodynamics the arm-retina time (ART) and arteriovenous passage time (AVP) were evaluated. The ART increased significantly from 9.4 +/- 1.8 to 11.8 +/- 2.2 s (P < 0.05) during elevated IOP, and the AVP was significantly prolonged from 1.6 +/- 0.4 to 3.0 +/- 0.8 s (P < 0.01) with IOP elevation as well. The increase in ART and AVP indicates an insufficiency of retinal autoregulation after an acute rise in IOP, even in healthy subjects. It appears that IOP values of > or = 30 mmHg may be detrimental to retinal perfusion in normals as well as in patients with POAG, who may have compromised retinal perfusion to begin with.

Adult↗
PubMed1996

Polysensory response characteristics of dorsal root ganglion neurones that may serve sensory functions during myocardial ischaemia.

OBJECTIVE: To determine the response characteristics of dorsal root ganglion neurones that may serve sensory functions during myocardial ischaemia. METHODS: Extracellular recordings were made from 54 spontaneously active and 5 normally quiescent dorsal root ganglion neurones (T2-T5) in 22 anaesthetized open-chest dogs under control conditions and during epicardial mechanical or chemical stimulation and myocardial ischaemia. RESULTS: The activity of 78% of spontaneously active and all quiescent neurones with left ventricular sensory fields was modified by left ventricular ischaemia. Forty-six spontaneously active neurones (85%) were polysensory with respect to mechanical and chemical stimuli. The 5 quiescent neurones responded only to chemical stimuli. Spontaneously active neurones associated with left ventricular mechanosensory endings (37 neurones) generated four different activity patterns in response to similar mechanical stimuli (high or low pressure active, high-low pressure active, high-low pressure inactive). A fifth group generated activity which was not related to chamber dynamics. Adenosine, adenosine 5'-triphosphate, substance P and bradykinin modified 72, 61, 65 and 63% of the spontaneously active neurones, respectively. Maximum local mechanical or chemical stimuli enhanced activity to similar degrees, as did ischaemia. Each ischaemia-sensitive neurone displayed unique activity patterns in response to similar mechanical or chemical stimuli. CONCLUSIONS: Most myocardial ischemia-sensitive dorsal root ganglion neurones associated with epicardial neurites sense mechanical and multiple chemical stimuli, a small population sensing only mechanical or chemical stimuli. Activity patterns generated by these neurones depend on their primary sensory characteristics or those of other neurones that may converge on them, as well as the type and magnitude of the stimuli that impinge upon their sensory fields, both normally and during ischaemia.

Adenosine↗
PubMed1996

Indocyanine-green angiography in patients with occult choroidal neovascularization.

Several studies have stressed the role of indocyanine-green (ICG) angiography in patients with occult choroidal neovascularization (O-CNV) secondary to age-related maculopathy (ARM). The present study was undertaken to evaluate the percentage of eyes that could be converted from O-CNV without suffering pigment epithelial detachment (PED) in well-defined CNV using ICG angiography with a scanning laser system. A total of 112 patients with ARM and O-CNV without PED were included in this prospective study. All patients underwent ICG angiography with a scanning laser system. The early phase (first 3 min) of the ICG angiogram was analyzed for the presence of a neovascular network, whereas focal or irregular hyperfluorescence was noted in the late phase. The early phase of the ICG angiograms revealed in 62 (55%) eyes a well-defined CNV. In 55 of these eyes, late irregular hyperfluorescent and hypofluorescent zones were observed. Another 27 eyes presented with focal hyperfluorescent areas in the latephase studies without having shown a well-demarcated area of neovascularization in the early phase of the ICG angiogram. This study confirms that ICG angiography is an important adjunctive method to fluorescein angiography. In more than 50% of eyes with O-CNV the ICG angiograms obtained with a scanning laser ophthalmoscope enable the visualization of a neovascular network in the early phase.

Aged↗
PubMed1996

Randomized controlled trial of ACE-inhibitors and beta-blockers with and without vasodilating activity in chronic glomerulonephritis.

A prospective double-blind, randomized study was conducted to compare the effects of the beta 1 antagonist, beta 2 agonist celiprolol (200 mg daily) on renal hemodynamics and protein excretion with those of the beta 1 antagonist atenolol (50 mg daily), the ACE-inhibitor ramipril (2.5 mg daily), and placebo in 11 patients with proteinuria > 400 mg/24 h due to chronic glomerulonephritis. All 4 substances were given in a double-blind, randomized manner according to a latin-square design over a period of 4 weeks with a wash-out period of 2 weeks in between. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured by inulin and PAH clearance. Proteinuria was assessed by urine sampling at the end of each treatment period. Mean arterial pressure (MAP) was reduced significantly (p < 0.01) by all 3 drugs compared to placebo (108 +/- 9 mmHg placebo, 98 +/- 12 mmHg atenolol, 101 +/- 11 mmHg celiprolol, and 98 +/- 8 mmHg ramipril). Celiprolol induced a significant increase in ERPF compared to placebo (322 +/- 109 ml/min under placebo versus 391 +/- 110 ml/min under celiprolol, p < 0.05). GFR was slightly but insignificantly increased under atenolol and celiprolol. Filtration fraction (FF) remained unchanged in case of atenolol and celiprolol treatment and was slightly but not significantly reduced by ramipril. Proteinuria was significantly (p < 0.05) reduced compared to placebo by all 3 drugs (1.8 +/- 1.3 g/24 h under placebo, 1.2 +/- 1.2 g/24 h under atenolol, 1.2 +/- 1.1 g/24 h under celiprolol, and 1.4 +/- 1.4 g/24 h under ramipril). These data demonstrate that new beta-blocking agents show favorable effects on proteinuria and renal blood flow in patients with chronic glomerulonephritis and arterial hypertension. This may be attributed to their vasodilating properties.

Adrenergic beta-1 Receptor Antagonists↗