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B Bravenboer

Publications and source records attributed to B Bravenboer.

52 records · Page 3Linked to original sources
PubMed1993

Is the corrected QT interval a reliable indicator of the severity of diabetic autonomic neuropathy?

OBJECTIVE: We investigated whether the corrected QT interval correlated with two other tests for diagnosing autonomic dysfunction in 60 type I diabetic patients with proven peripheral neuropathy. The mean age +/- SD was 48.3 +/- 11.2 yr, the mean duration of diabetes was 24.9 +/- 11.4 yr, and the mean HbA1 was 9.3 +/- 2.4%. RESEARCH DESIGN AND METHODS: All patients underwent three autonomic function tests: 1) the standard five cardiovascular Ewing tests, each scored 0 (normal), 0.5 (borderline), or 1.0 (abnormal). We used the sum of the abnormal findings for the analysis, the cardiovascular autonomic score; 2) measurement of the corrected QT interval taken from a routine electrocardiogram recording; and 3) static and dynamic pupillometry: measurement of dark adapted pupil diameter as percentage of total iris diameter and of pupil constriction latency using an infrared light reflex technique. RESULTS: No significant correlation was found between age, duration of diabetes, or HbA1 and any of the autonomic function tests, except for one between age and cardiovascular autonomic score (r = 0.3202, P = 0.0126). Corrected QT interval did not correlate with cardiovascular autonomic score, pupil diameter, or constriction latency. A significant inverse correlation was found between cardiovascular autonomic score and pupil diameter (r = -0.4861, P < 0.001) and constriction latency (r = 0.3783, P < 0.001). Pupil diameter and constriction latency correlated well (r = -0.4276, P < 0.001). CONCLUSIONS: The corrected QT interval did not correlate with cardiovascular autonomic tests nor pupillometry results. The corrected QT interval therefore should not be used for the diagnosis of the severity of diabetic autonomic neuropathy.

Autonomic Nervous System↗
PubMed1993

The relationship between serum triiodothyronine and thyroxine concentrations in hyperthyroidism.

In toxic nodular goitre relapses of hyperthyroidism after medical therapy probably are more common than in toxic diffuse goitre. It has also been reported that in patients with toxic diffuse goitre a high ratio of triiodothyronine (T3) and thyroxine (T4), initially or during medical treatment, predicts a relapse of the hyperthyroidism after cessation of therapy. We therefore studied the relationship between T3 and T4 in untreated patients with toxic diffuse goitres (n = 46, mean ratio T3/T4 29.6 nmol/mumol +/- 10.7 SD) and toxic nodular goitres (n = 12, ratio 29.3 +/- 17.1), and found no significant difference. Both groups differ significantly from normal controls (n = 16, ratio 14.6 +/- 1.5, P < 0.01). From the patients with toxic diffuse goitres we compared two groups. Patients in the first group remained in remission after short-term medical treatment (n = 10); the second group contains patients with a relapse of hyperthyroidism (n = 10). Differences between both groups in the median ratio of T3 and T4 were assessed before the start of treatment, at 4 and at 8 weeks. No significant differences were found between the two groups. The ratio of T3 and T4 is not helpful in distinguishing diffuse and multinodular toxic goitre or in determining the prognosis after medical treatment of hyperthyroidism caused by a hyperfunctioning thyroid gland. However, recurrence of hyperthyroidism was found in 3 patients with a T3/T4 ratio > 60 nmol/mumol after 8 weeks of treatment.

Adult↗
PubMed1992

Potential use of glutathione for the prevention and treatment of diabetic neuropathy in the streptozotocin-induced diabetic rat.

It has been shown that parameters of oxidative stress are increased in experimental diabetic neuropathy. The glutathione redox system is one of the intracellular scavenger systems for neutralizing free oxygen radicals. In this investigation we studied the effect of glutathione-treatment on the development of diabetic neuropathy in streptozotocin-induced diabetic rats by measuring sensory and motor nerve conduction velocities. The total study period was 10 weeks. Four groups of rats were studied: Group 1 consisted of non-diabetic, age-matched control rats; Group 2, of diabetic rats treated with placebo from week 0 to 10; Group 3, of diabetic rats treated with 200 mg glutathione/kg body weight i.v. two times per week from weeks 0 to 10; and Group 4, of diabetic rats treated with placebo from weeks 0 to 4 and as Group 3 from weeks 4 to 10. The sensory and motor nerve conduction velocity of rats treated prophylactically with glutathione (Group 3) were significantly different from those of rats treated with placebo (Group 2) or with glutathione administered at a later time point (Group 4). Complete restoration of sensory and motor nerve conduction velocity was not reached. There was a significant improvement in motor nerve conduction velocity from weeks 4 to 6 (p less than 0.005), but not in sensory nerve conduction velocity in the delayed treatment group (Group 4). In conclusion, treatment with glutathione, a free radical scavenger, is partially effective in the prevention of diabetic neuropathy in streptozotocin-induced diabetic rats, but is of limited value when the neuropathy is already present.

Animals↗
PubMed1992

Subclinical diabetic neuropathy: similarities between electrophysiological results of patients with type 1 (insulin-dependent) and type 2 (non-insulin-dependent) diabetes mellitus.

Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetic patients share many clinical and biochemical characteristics. However, sural nerve biopsies from patients with advanced and chronic neuropathy show ultrastructural differences between these two groups. We investigated whether at a subclinical stage of the illness, when Type 1 and Type 2 diabetic patients are clinically uniform and the histopathological nerve alterations are not advanced, comparison between the two diabetes groups might show differences in nerve fibre involvement related to the different pathogeneses of the neuropathies. A total of 88 diabetic patients (52 Type 1 and 36 Type 2), with a subclinical form of polyneuropathy were selected. The clinical neurophysiological examination consisted of motor and sensory nerve conduction studies, Hoffmann (H)-reflex, single fibre electromyography and static as well as dynamic pupillometry. With regard to clinical neurophysiological abnormalities, the severity of the polyneuropathy appeared to be equal in both groups. Despite the absence of clinical symptoms the neurophysiological abnormalities were pronounced and it was impossible to differentiate Type 1 diabetic patients from Type 2 diabetic patients on a clinical neurophysiology basis when correcting for differences in age, height, and duration of illness. In the Type 1 diabetic group as well as in the Type 2 diabetic group the autonomic nerve fibres and nerves in the legs were more frequently affected than the thick myelinated nerves in the arms. These findings do not support the assumption that there is a difference in the manifestation of polyneuropathy between Type 1 and Type 2 diabetic patients.

Autonomic Nervous System↗
PubMed1992

Thermal threshold testing for the assessment of small fibre dysfunction: normal values and reproducibility.

Small and large fibre neuropathy are common findings in patients with long-standing diabetes mellitus. The Thermal Threshold Tester was tested to obtain normal values for thermal perception threshold for warmth and cold. This device produces thermal stimuli by means of a Peltier element placed on the skin. Warm and cold thresholds are measured using a forced choice method with an up-and-down-transform rule and expressed in degrees Celsius (degree C). Thresholds were measured at the right wrist and right foot in 80 normal subjects, divided into four age groups; 25-34, 35-44, 45-54, and 55-65 years. The repeatability coefficient was assessed by twice measuring 39 diabetic patients without known neuropathy. Warm thermal threshold in the hand showed a significant increase with age from 0.09 +/- 0.5 (mean +/- SD) in the youngest age group to 0.17 +/- 0.08 degree C (p less than 0.05) in the oldest age group. Cold thermal threshold in the hand (varying between 0.08 +/- 0.04 and 0.14 +/- 0.05 degree C) and warm thermal threshold in the foot (varying between 2.45 +/- 1.93 and 4.06 +/- 2.57 degrees C) did not differ significantly between the four age groups. There was a significant increase in cold thermal threshold in the foot with age, increasing from 0.31 +/- 0.24 to 0.56 +/- 0.44 degree C (p less than 0.05). Reproducibility in the diabetic subjects was good for measurements of warm and cold threshold in the hand, but poor for warm threshold in the foot in the normal range and for cold thermal threshold in the abnormal range.

Adult↗
PubMed1991

Logistic multiple regression analysis of factors predicting recurrence of hyperthyroidism after medical treatment of toxic diffuse goitre.

In order to determine which factors predict the outcome of short term antithyroid drug treatment we studied 42 patients with diffuse goitre in whom 43 instances of thyrotoxicosis were treated. Treatment duration ranged from 24 to 61 wk (median 30 wk). All patients received high-dose carbimazole and thyroid hormone substitution. Patients in remission were followed for 39 to 134 wk (median 73 wk). The relapse rate at 1 yr and at 2 yr after cessation of antithyroid drug treatment was 51%. Of the parameters studied presence or absence of eye signs and initial serum levels of thyroxine, triiodothyronine and immunoglobulin-G in the relapse group and in the remission group showed significant differences in univariate analysis. No significant differences were found for age, sex, family history of thyroid disease, thyroid gland volume or TSH-receptor stimulating autoantibodies. Linear discriminant analysis shows that of the four remaining factors thyroxine is not important in separating both groups. Cox analysis yields only initial serum triiodothyronine and eye signs as significant prognostic factors. With these two factors 18 out of 23 predictions of remission and 16 out of 18 predictions of relapse in the 41 patients with known initial serum triiodothyronine concentrations are correct. Such predictions can be used in the choice of therapy, short-term medical treatment for patients with a low risk and long-term medical treatment or, at the appropriate time, a destructive form of therapy for patients with a high risk of relapse.

Analysis of Variance↗
PubMed1986

A comparison of porcine and human thyroid tissue in the assay of thyroid stimulating immunoglobulins.

The central role of Thyroid Stimulating Immunoglobulins (TSI) in the pathogenesis of the hyperthyroidism of Graves' disease has become generally accepted and a wide variety of assays for the detection of these antibodies has been developed. The dependence on the availability of human thyroid tissue makes most of these assays unsuitable for routine clinical use, a problem circumvented by the use of nonhuman thyroid tissue in some TSI assays. We therefore compared porcine and human thyroid tissue in a TSI assay based on in vitro cAMP generation. No major differences in within and between run variation were found and, with some notable exceptions, a reasonable correlation could be demonstrated between the results in both assays (R = 0.89, P less than 0.001). However, the sensitivity of the porcine TSI assay is only 60% of the estimated sensitivity of the human TSI assay. In spite of the practical advantages this porcine TSI assay, and possibly also other TSI assays using non-human thyroid tissue, cannot totally replace human TSI assays. The value of these assays in predicting the outcome of medical treatment of Graves' disease remains to be established.

Animals↗
PubMed1983

Congenital meningeal sarcoma--a case report.

A 30-year-old multigravida woman was admitted to the obstetrical unit in the third trimester of gestation, because of a large-for-date uterus. Repeated ultrasonic examinations over a 2-week period revealed an increase in biparietal diameter far too large to be normal. This progressive asymmetrical hydrocephalus was diagnosed as caused by an intracranial space-occupying lesion in the middle cranial fossa. Because of the only minimal thickness of the cerebral cortex prognosis was judged so poor, that labor was induced. A stillborn female infant was delivered vaginally after an ultrasonically guided transabdominal and later transcervical encephalocentesis. Autopsy revealed hydrocephalus and section through the fixed brain showed that the mentioned mass was an undifferentiated meningeal sarcoma that filled the left middle cranial fossa. Microscopically the sarcoma was invading the brain tissue. Definitions of the term "congenital brain-tumors" vary among authors. "Congenital" can be interpreted as "derived from embryonal tissue" or as "originating in utero". Congenital intracranial neoplasms are very rare. Antenatally intracranial tumors have been reviewed by Wells, Solitare and Farwell. Only a few cases of congenital brain tumors arising in the meninges have been reported in these reviews. The genesis of the tumor is explained as derived from multipotential cells. The undifferentiated type of a meningeal sarcoma has a poor prognosis. Most meningeal sarcoma present with progressive hydrocephalus.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗