Biomedical subjects

J Oosting

Publications and source records attributed to J Oosting.

At least 55 records · Page 3Linked to original sources

PubMed1995

The effect of extrahepatic cholestasis on liver regeneration after partial hepatectomy in the rat.

Liver regeneration after partial hepatectomy was studied in four groups of rats: control rats (n = 12), rats with 1 week of common bile duct obstruction (n = 11), rats with restoration of bile flow after 1 week of obstruction (n = 9) and a sham-operated group (n = 7). Parameters of DNA synthesis--thymidine kinase activity and in vivo bromodeoxyuridine incorporation--were measured at partial hepatectomy (T = 0), and 24 and 48 h after partial hepatectomy. During common bile duct obstruction, DNA synthesis was already stimulated at T = 0, but partial hepatectomy in common bile duct obstruction rats induced a delayed DNA synthesis. After 1 week of restoration of bile flow, normal DNA synthesis had returned at T = 0, but DNA synthesis after partial hepatectomy was still delayed. The sham-operated rats showed a normal regeneration response after partial hepatectomy assessed by bromodeoxyuridine incorporation but delayed as assessed by thymidine kinase activity, partly due to the impaired physical condition of the animals. The present data support the hypothesis that during cholestasis, regeneration promoting, and inhibitory factors accumulate in the liver, their balance determining whether regeneration after partial hepatectomy will occur in a normal, enhanced or delayed way.

Animals↗

PubMed1995

Hemodynamic basis of oscillations in systemic arterial pressure in conscious rats.

In conscious resting rats, beat-to-beat fluctuations in systemic mean arterial pressure (MAP) were compared with those in cardiac output and those in blood flow in the renal, mesenteric, and hindquarter vascular beds. Spontaneous oscillations (lability) in MAP were observed in frequency bands centered about 1.6 Hz (high: HF), 0.4 Hz (mid: MF), and 0.13 Hz (low: LF). Lability of MAP was confined within the LF (approximately 8 s) band. Lability of cardiac output, on the other hand, showed primary HF oscillations. LF oscillations in regional blood flow were most prominent in the mesenteric and renal vascular beds. In these beds, LF oscillations in blood flow showed negative phase angles with MAP, whereas those between MAP and hindquarter blood flow were positive. Cross correlation analysis indicated that approximately 2 s following a LF change in MAP, LF changes in mesenteric and renal blood flow occurred opposite to those of MAP. Changes in hindquarter flow were negatively correlated with those in MAP about zero time delay. Admittance gains were > or = 1 across all frequencies for all vascular beds, indicating the absence of autoregulation. This hemodynamic pattern suggests that myogenic mechanisms predominantly control mesenteric and renal blood flow in a nonautoregulatory but rather superregulatory manner, while autonomic mechanisms regulate hindquarter blood flow. Thus, in conscious resting rats, spontaneous fluctuations in systemic arterial pressure predominantly exhibit slow (approximately 8 s) oscillations, which do not arise from fluctuations in cardiac output, but originate from regionally specific myogenic oscillatory mechanisms contributing to resistance to flow.

Animals↗

PubMed1995

Ivermectin detection in serum of onchocerciasis patients: relationship to adverse reactions.

Ivermectin treatment of onchocerciasis patients can be accompanied by adverse reactions. Not much is known concerning the pathogenesis of these reactions. Previous studies have demonstrated that the occurrence and extent of adverse reactions are related to infection intensity. However, some severely infected patients experience relatively few adverse effects. The aim of the present study was to investigate whether this seeming discrepancy could be due to diminished ivermectin absorption. Ivermectin concentrations one and two days after treatment were measured by high-performance liquid chromatography in sera of 71 skin snip-positive onchocerciasis patients (21 without reactions, 25 with mild reactions, 14 with moderate reactions, and 11 with severe reactions). The overall mean +/- SD ivermectin concentrations one and two days after a single oral dose (150 micrograms/kg) were 16.4 +/- 6.4 and 6.6 +/- 3.1 ng/ml, respectively. The overall mean +/- SD half-life was estimated to be 19.9 +/- 8.6 hr. The data presented did not show a relationship between ivermectin concentrations and the grade of adverse reactions.

Chromatography, High Pressure Liquid↗

PubMed1994

Colorectal cancer prognosis and expression of exon-v6-containing CD44 proteins.

CD44 variants containing v6 confer metastatic potential to rat carcinoma cell-lines. In man, CD44v6 is increasingly expressed during colorectal tumour progression. In 68 colorectal carcinoma patients, survival analysis showed that CD44v6 expression in the tumours was associated with tumour-related death. In patients who had an apparently radical resection of their primary tumour, CD44v6 expression had prognostic value independent of Dukes' stage. CD44v6 expression may reflect propensity for metastasis after apparently curative surgery, making adjuvant therapy an option in these patients.

Carrier Proteins↗

PubMed1994

Metacarpophalangeal pattern profile analysis in Sotos and Marfan syndrome.

Patients with Sotos and Marfan syndrome have unusually long metacarpals and phalanges which may make the differential diagnosis difficult in younger children. Using Q-scores, we compared metacarpophalangeal pattern profile (MCPP) analysis in these two syndromes and identified distinct and different pattern profiles. This illustrates that the MCPPs are specific in these syndromes, even at an early age, and not related solely to the unusually long metacarpals and phalanges. For this study we used data from 50 Sotos patients (34 from the United Kingdom and 16 from the Netherlands, with a total of 95 hand films) and 36 Marfan patients (from the Netherlands, with 98 hand films). Of all patients over age 3 years the bone length (including the epiphysis) was determined. The patients under 7 1/2 years (29 Sotos and 12 Marfan) were also measured without inclusion of the epiphysis. The patients measured without epiphysis had a relative short metacarpal 1 (MC1) and long distal phalanx 1 (DPh1) in Sotos syndrome, and a relative long MC1 and short DPh1 in Marfan syndrome. Between age 3 and 7 1/2 years more than 90% of the films could be classified correctly using these two variables. Of the roentgenograms measured with epiphyses, about 80% were classified correctly.

Adolescent↗

PubMed1994

Catechol-O-methyltransferase in vitiligo.

Catechol-O-methyltransferase (COMT) is involved in the metabolism of neurotransmitters such as epinephrine, norepinephrine and dopamine. For melanocytes, the enzyme is of particular importance in preventing the formation of toxic o-quinones during melanin synthesis. It has been suggested that COMT plays a regulatory role in melanin synthesis. Indeed, when the melanin precursor molecule DHI(2C) is methylated by COMT it is no longer available for incorporation into melanin. Auto-destruction by intermediates of melanin metabolism has been implicated in the aetiology of vitiligo. Therefore enzyme activities in vitiligo patients and in healthy controls were compared. Systemic COMT activities were measured using red blood cells (RBC) as starting material. However, as local alterations in COMT activity may be specifically involved in vitiligo, the enzyme activity was also measured in epidermal homogenates. Finally, to ascribe epidermal COMT activity to the responsible cell type(s), enzyme activity was measured in cultured vitiligo non-lesional melanocytes and melanocytes from healthy controls as well as in cultured keratinocytes from lesional skin and in purified keratinocytes from control skin. It was found that epidermal homogenates from vitiligo patients expressed higher levels of COMT activity than homogenates from healthy controls. Such differences were not found at the systemic level (i.e. in RBC) nor could they be explained by measurements on separately cultured epidermal cell types, indicating that the COMT activity was induced at the tissue level by extracellular factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Allele loss on chromosomes 10 and 17p and epidermal growth factor receptor gene amplification in human malignant astrocytoma related to prognosis.

Patients with high-grade astrocytomas have a poor prognosis. However, considerable variation exists within this group of patients with respect to post-operative survival. In order to determine whether genetic alterations might be of help in subdividing this group, we used allele loss on chromosomes 10 and 17p and epidermal growth factor receptor (EGFR) gene amplification in the tumours as genetic parameters and determined their prognostic value. A series of 47 malignant (grade III and grade IV) tumours were genetically characterised, and four types of tumours were found. Type 1 tumours had loss of heterozygosity on chromosome arm 17p (LOH 17p) as the sole genetic alteration. Patients with this type of tumour were relatively young (mean age 39 years) and had a median survival period of 17 months. Type 2 tumours displayed only allele loss on chromosome 10 (LOH 10), type 3 tumours had LOH 10 + LOH 17p and type 4 tumours contained LOH 10 + EGFR gene amplification. Patients with types 2, 3 and 4 tumours were older (mean ages 59, 65 and 54 years respectively) and had a shorter survival (median duration 6, 3 and 2 months respectively) than type 1 patients. Multivariate analysis indicated that the genetic subdivision was a significant prognostic variable. In this study, age proved to be of minor importance with regard to survival. Our study revealed a predominance of frontally located tumours in patients with type 1 tumours, i.e. with LOH 17p only.

Adult↗

PubMed1994

C-reactive protein and interleukin-6 are elevated in onchocerciasis patients after ivermectin treatment.

Ivermectin treatment of onchocerciasis can induce adverse reactions. Mechanisms underlying these reactions are poorly understood but may include activation of neutrophils. This study investigated the acute-phase response in onchocerciasis patients during 2 days after ivermectin treatment. The acute-phase protein C-reactive protein (CRP) and cytokines that mediate the acute-phase response (tumor necrosis factor-alpha [TNF alpha] and interleukin-6 [IL-6]) were measured in 144 skin snip-positive onchocerciasis patients and 12 skin snip-negative controls who received one dose of ivermectin (150 micrograms/kg). No elevated TNF alpha levels were found, but IL-6 and CRP were elevated in 25.7% and 50.7% of the patients, respectively, after ivermectin treatment. Most patients (89.2%) with raised IL-6 also had raised CRP. Such increases were not observed in controls and in patients were correlated with adverse reactions and microfilarial densities. These findings suggest a possible role of the acute-phase response in microfilarial destruction following ivermectin treatment.

Biomarkers↗

PubMed1994

Masticatory electromyographic activity in healthy young adults and myogenous craniomandibular disorder patients.

UNLABELLED: The electromyographic (EMG) activity of the masseter and the anterior temporalis muscles were compared between 60 healthy controls and 61 myogenous craniomandibular disorder (CMD) patients. Subjects were asked to clench at 10% and at 50% of their maximum voluntary clenching level. The effects of CMD, age and gender were statistically analysed with the use of the analysis of covariance. The correlations between EMG asymmetries and the lateral slide from the retruded contact position to the intercuspal position and the asymmetry in the number of post-canine tooth contacts between the left and the right side were investigated. The CMD patients showed lower masseter EMG activities than the controls, whereas the anterior temporalis EMG activity was not different between the two groups. The activity index, relating the anterior temporalis EMG activity to the activity of the masseter muscles, confirmed the presence of a relatively high temporalis activity in the CMD group. No significant differences were found in the EMG asymmetries between the controls and the CMD patients. Males showed higher masticatory EMG activities than females. These gender effects were significant for the anterior temporalis at the 10% and 50% level and for the masseter muscle at the 10% level. The anterior temporalis EMG activity declined with age. No age related effects were observed in the masseter EMG. The lateral slide was larger and more prevalent in the CMD group. A significant correlation between the lateral slide and the anterior temporalis EMG was found for the CMD group at the 10% level. No correlation was found between the EMG asymmetry and the asymmetries in post-canine tooth contacts. IN CONCLUSION: significant CMD, age and gender effects were observed in the masticatory EMG activities of a group of myogenous CMD patients and a control group.

Adolescent↗

PubMed1994

Morphology and function of the corneal endothelium after long-term contact lens wear.

PURPOSE: To examine whether corneal hydration control is impaired in corneas with endothelial morphologic changes (increased variation in cell size and cell angularity) due to long-term low gas-permeable contact lens wear. METHODS: Twenty-one long-term wearers of low gas-permeable contact lenses (mean age, 41 years +/- 8 SD) and 18 age-matched controls (mean age, 42 years +/- 8 SD) were studied. To assess endothelial morphology, endothelial photographs were taken, enlarged 400X, scanned into a computer, and evaluated. Hydration control was assessed by a corneal stress test. Corneal swelling was induced by applying low gas-permeable soft contact lenses for 2 hours during eye closure. After the lenses were removed, the rate of deswelling was determined using optic pachometry. RESULTS: Morphologic analysis of the endothelial photographs showed a significant increase of polymegethism (P < 0.01) and pleomorphism (P < 0.01) in the group wearing contact lenses compared with the control group. The percentage of recovery of corneal thickness per hour (PRPH) from induced swelling proved to be significantly lower (P = 0.03) and the induced swelling proved to be significantly lower (P < 0.01) in the group wearing contact lenses than in the control group. Multiple regression analysis showed that the PRPH decreased as the morphologic alterations increased. However, this trend appeared not to be significant at the 5% level. A significant relationship was found between morphologic parameters and induced swelling, indicating that induced swelling decreased as the morphologic alterations increased. CONCLUSION: The results of this study indicate that increased endothelial polymegethism and pleomorphism may be accompanied by a decreased corneal hydration control in people who wear contact lenses.

Adult↗

PubMed1993

In situ glucose-6-phosphate dehydrogenase activity during development of pre-implantation mouse embryos.

Glucose-6-phosphate dehydrogenase activity was analysed cytophotometrically in oocytes and pre-implantation embryos of mice. A bimodal distribution pattern was not found. Therefore, female and male embryos could not be discriminated on the basis of linkage of the enzyme with the X-chromosome during the pre-implantation period. The dehydrogenase activity in ovulated eggs and pre-implantation embryos up to the 8-cell stage was 65% of that present in follicular oocytes. In morulae and blastulae, the activity was further decreased to a level that was only 10-20% of the activity present in oocytes. The dramatic decrease in dehydrogenase activity could not be explained by modulation of the enzyme molecules, because KM values did not vary strongly. It is unlikely that the abundant activity of glucose-6-phosphate dehydrogenase in oocytes is due to high activity of the pentose phosphate pathway because of the low activity of 6-phosphogluconate dehydrogenase, the next step in this pathway. It is concluded that high activity of glucose-6-phosphate dehydrogenase in oocytes is needed for keeping oocytes viable, and for generation of NADPH which is important for the fertilization process.

Animals↗

PubMed1993

Awareness and recall during general anesthesia. Facts and feelings.

BACKGROUND: Experiences of awareness and recall during general anesthesia can be most distressing for patients. To obtain relevant information, the authors systematically interviewed patients in whom awareness during surgery had occurred, and questioned them about their experiences. METHODS: Twenty-six patients, referred by colleagues, described the facts and feelings they had experienced during the period of awareness, and whether these had had any consequences. Available anesthetic records were independently judged by three experienced anesthesiologists for relevant parameters. RESULTS: Auditory perception and the sensation of paralysis were most frequently mentioned, followed by the sensation of pain. Patients' feelings were mostly related to anxiety, panic, powerlessness, and helplessness. Eighteen patients (70%) experienced unpleasant aftereffects, including sleep disturbances, dreams and nightmares, and flashbacks and anxiety during the day. Only nine patients (35%) had informed their anesthesiologists about what had taken place. Twelve anesthetic records were assessed. In three, the occurrence of awareness had been indicated, while, in a fourth, it was noted that an amnesic drug had been given at a moment of increased blood pressure. Experienced anesthesiologists were unable to reliably distinguish awareness cases from matched controls when judging the records. CONCLUSIONS: Details recalled from the period of awareness correspond with data from the literature. The anesthesiologist's role in discussing, and dealing with, traumatic experiences related to anesthesia may be of great importance. The hand-written anesthetic record is of limited value in retrospectively explaining why awareness and recall have occurred.

Adult↗

PubMed1993

Neutrophil activation in ivermectin-treated onchocerciasis patients.

Ivermectin is a safe and effective drug for onchocerciasis treatment. In certain individuals, however, therapy is accompanied by adverse reactions. The mechanisms underlying these reactions are not yet known. The aim of the present study was to investigate whether neutrophils are involved in the development of these adverse reactions. Elastase and lactoferrin, two markers for the release of neutrophil azurophilic and specific granule contents respectively, were measured by radioimmunoassays in plasma of onchocerciasis patients with varying degrees of side effects, as well as in control subjects before and 1 and 2 days after ivermectin treatment. A considerable increase of elastase levels after treatment was observed, whereas lactoferrin levels did not change. The percentage of patients with elevated elastase levels was significantly correlated with the degree of side effects. These findings suggest that neutrophil activation may be involved in the development of adverse reactions in these patients.

Cell Degranulation↗

PubMed1993

Medical risk classification of dental patients in The Netherlands.

This study centers on the general health of dental patients, evaluated on the basis of the physical status classification system of the American Society of Anesthesiologists (ASA). A total of 4,087 patients completed a risk-related, patient-administered questionnaire. On the basis of their medical data, a computerized ASA classification was determined for each patient: 63.3 percent were in ASA class I, 25.7 percent in class II, 8.9 percent in class III, and 2.1 percent in class IV. After verification and/or consultation with the physician, the dentist also determined the ASA class, and this was compared with the computerized outcome. The agreement expressed as a kappa value was 0.64; the computer result generally placed the patient in a higher category of medical risk. The computer-determined ASA classes differed among the various dental practices (chi 2 = 262.9; df = 138; P < .01). It is possible to estimate the risk class of dental patients on the basis of standardized medical information only; however, the definitive ASA class can only be determined after verification of the patient's reply or, in some cases, after consultation with a physician.

Adult↗

PubMed1993

Gastric metaplasia and Helicobacter pylori infection.

Duodenal and antral mucosal biopsy specimens were obtained from 139 patients with dyspeptic complaints to study the prevalence and extent of gastric metaplasia in the duodenal bulb in relation to Helicobacter pylori (H pylori) infection and duodenal ulcer disease. On logistic regression, the presence and extent of gastric metaplasia was not significantly associated with H pylori infection. The prevalence of gastric metaplasia, however, was found to be higher in patients with current or past evidence of duodenal ulcer disease in comparison with subjects with functional dyspepsia (p = 0.01). A follow up study on 22 patients before and at least one year after eradication of H pylori showed that the mean extent of gastric metaplasia did not change significantly after eradication and did not differ when compared with 21 patients with persisting infection. It is concluded that the unchanged gastric acid output after eradication of H pylori is a more important factor in the development of gastric metaplasia than the H pylori related inflammatory process.

Adult↗

PubMed1993

Time-dependent efficacy of antihypertensive agents in spontaneously hypertensive rats.

The efficacy of antihypertensive agents was compared when given at different time points in the circadian rhythm. Spontaneously hypertensive rats (SHRs) were kept on a 12/12-h cycle with lights on/off at 07:00/19:00 h. A computerized system was used to measure intraarterial blood pressure and heart rate continuously. Agents or vehicle were intravenously injected at two time points. One at the beginning of the sleeping period, at which low efficacy was expected (T = 10), and one at T = 16, which is 3 h before the circadian peaks in blood pressure (BP) and heart rate (HR), aimed at reducing the rise in BP and HR at awakening. The hypotensive effect of propranolol, metoprolol, labetalol, prazosin, clonidine, and rilmenidine was greater when injected at T = 16 than at T = 10 (p < 0.05 for propranolol, metoprolol, and rilmenidine). In contrast, the renal vasodilators captopril and tertatolol were more potent after injection at T = 10. Felodipine was equally effective at both time points. Thus, the effects of antihypertensive agents are related to the phase of the circadian rhythm. The data on the sympatholytic agents in general and beta-blockers and centrally acting agents in particular support antihypertensive regimens with timed administrations.

Animals↗

PubMed1993

Concurrent parasitic infections in onchocerciasis and the occurrence of adverse reactions after ivermectin treatment.

Ivermectin is a safe, effective, and relatively well-tolerated drug for the treatment of human onchocerciasis. However, due to side effects of the drug, large-scale ivermectin distribution without medical supervision is not recommended. The mechanisms involved in the pathogenesis of ivermectin-induced adverse reactions are not yet known. Since onchocerciasis patients are likely to have concurrent parasitic infections, we investigated whether side effects that occur after ivermectin treatment could be related to the presence of parasite eggs and cysts in stool samples prior to treatment. One hundred twenty-nine onchocerciasis patients were treated with a single dose of ivermectin (150 micrograms/kg) and side effects were graded according to the classification of Greene and others. Stool samples were collected before and three days after treatment. A high percentage (80.5%) of the patients reported adverse effects (57% mild, 14.1% moderate, and 9.4% severe reactions). Most (95.1%) of the patients had one or more concurrent parasitic infections. No relationship could be found between the occurrence and extent of side effects and the severity of concurrent intestinal parasitic infections. However, side effects were significantly correlated with pretreatment microfilarial counts. Ivermectin treatment did not induce significant short-term changes in Trichuris trichiura or Schistosoma mansoni egg counts. However, a significant reduction in Ascaris lumbricoides egg counts and Entamoeba coli cyst loads was observed; a cure rate of 46% for cysts was reached. In contrast, hookworm egg production increased after ivermectin treatment. Further studies are required to verify ivermectin-induced changes in cyst and hookworm loads as well as the significance of these findings.

Animals↗

PubMed1993

Malaria chemosuppression in pregnancy. I. The effect of chemosuppressive drugs on maternal parasitaemia.

A randomized prophylactic drug trial was conducted in a malaria holoendemic area, in the Muheza District of Tanzania. Of 327 pregnant women, 124 received proguanil (PROG), 113 chloroquine (CQ), 90 the proguanil and chloroquine combination (CQ+PROG). Prophylaxis was supervised. Chemosuppressive efficacy was measured through the incidence of malaria breakthrough parasitaemias and clinical episodes. Groups were comparable by age, parity, residential area, and enrollment gestational age. Compliance and drug bio-availability was good. The median breakthrough time of the first parasitaemia episode for primigravidae (PG) and multigravidae (MG) was significantly shorter for the CQ group (PG = 56, MG = 78 days) than in the PROG (PG = 97, MG = 112 days) and the CQ+PROG (PG = 138, MG = 140 days) groups. 56% of the CQ group experienced 2 or more clinical episodes compared to 19% (PROG) and 10% (CQ+PROG). PROG and CQ+PROG did not differ significantly. Parasite densities and in vitro tests suggested that CQ selected for more and highly resistant strain(s). Proguanil is suitable for prophylaxis. However, proguanil resistance should be monitored as well as controlled drug distribution and usage. Malaria control strategies other than chemoprophylaxis should be investigated.

Adolescent↗