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Biomedical subjects

A Jansen

Publications and source records attributed to A Jansen.

At least 109 records · Page 6Linked to original sources
PubMed1992

Arginase is a major pathway of L-arginine metabolism in nephritic glomeruli.

L-arginine can be metabolized to nitric oxide (NO) by nitric oxide synthase (NOS) and to urea and L-ornithine by arginase. Competition between these pathways for L-arginine in inflammatory sites has been suggested. In experimental glomerulonephritis glomeruli produce nitrite; a major source is macrophages. We hypothesized that arginase is present in glomeruli and may compete for substrate with NOS in glomerulonephritis. Therefore we examined both pathways in isolated nephritic glomeruli and peritoneal macrophages. Arginase activity was present in glomeruli, increased by > 500% in nephritic glomeruli compared to controls, and was predominant over NOS. Activity increased with L-NMMA (a NOS inhibitor), but this trend did not reach statistical significance. In macrophages both pathways were present; NOS predominated basally but this was reversed by L-NMMA. In contrast with glomeruli macrophage arginase activity increased after LPS stimulation. Levels of macrophage arginase activity could not account for activity in nephritic glomeruli, suggesting another source of arginase. This is the first demonstration of high arginase activity of nephritic glomeruli. Competition between arginase and NOS pathways suggests a regulatory mechanism of L-arginine metabolism within the glomerulus, with implications for the pathogenesis of injury and scarring in glomerulonephritis.

Amino Acid Oxidoreductases↗
PubMed1992

Laparoscopic gastrointestinal and gallbladder surgery: will the promise be fulfilled?

The results of the first 181 consecutive patients who underwent laparoscopic cholecystectomy and 12 patients who underwent laparoscopic colon resection in our hospital are described. Our results show that laparoscopic cholecystectomy has proved to be the standard surgical procedure for treating gallbladder disease. The place of laparoscopic surgery in the treatment of other abdominal diseases is less clear. Our results in laparoscopic colon surgery indicate that a laparoscopic approach in segmental colon resection is feasible. The operation time is long, however, expressing the long learning curve for the operating team, as well as the technical difficulties encountered with this minimal invasive method. On the other hand, it has been proved that large abdominal operations can be performed via the laparoscope. By improving the laparoscopic instruments and increasing the laparoscopic surgeon's experience, further application of this method in gastrointestinal surgery may be expected. Surgeons should, however, be aware of the long learning curve involved in advanced laparoscopic surgery.

Adolescent↗
PubMed1992

[Psychological testing within the scope of social psychiatric service].

As a psychologist working within the Social Psychiatric Service I find myself exposed to certain assignments and methodological expectations. One of the most common images is that of a "trick- and test specialist" that most of the time would appear along with multitude of open and hidden fantasies towards psychological methods of testing. It's not always easy to meet such expectations appropriately. But due to the severe consequences that may arise from statements of the Service we have to emphasise the limitations of such means of assistance. The mathematical operations of test constructors may be extraordinarily brilliant; the possibilities of transforming psychic phenomena into abstract numbers create however, as many complications as the choice of social scales and standards we have to make for our measurements. Hence, psychological results will still have to follow several different steps of examination that are reciprocally related to each other, even when using methods that seem to provide more comfortable, easier solutions.

Attitude of Health Personnel↗
PubMed1992

The relaxant properties in guinea pig airways of S-nitrosothiols.

Several cellular constituents of the lung have the capacity to synthesize a factor capable of relaxing smooth muscle which has the physicochemical properties of nitric oxide (NO). In other systems, it has been shown that NO may be stabilized in the plasma and cellular milieu by reduced thiol in the form of an S-nitrosothiol (RS-NO). These compounds have half-lives that are significantly greater than that of NO, and also retain the vasorelaxant activity of NO, which is mediated by activating guanylate cyclase and raising cyclic GMP levels. The effects of RS-NO and their potential mechanism of action on airways, however, have not been previously investigated. In this study, we have examined the smooth muscle relaxant properties of several biological and synthetic RS-NO on guinea pig trachea. Our data reveal that RS-NO are generally potent airway smooth muscle relaxants with at least a partial effect through stimulation of cyclic GMP. Relaxations were attenuated significantly by the guanylate cyclase inhibitor methylene blue (P less than .05), and RS-NO-induced increases in cyclic GMP were demonstrated (P less than .0005). The IC50 values for S-nitroso-glutathione, S-nitroso-cysteine, S-nitroso-homocysteine, S-nitroso-N-acetylcysteine, S-nitroso-penicillamine and S-nitroso-captopril were 0.99 +/- 0.09, 3.2 +/- 0.2, 2.1 +/- 0.3, 2.1 +/- 0.8, 1.8 +/- 0.8 and 20 +/- 0.7 microM (mean +/- S.E.M.), respectively. In this system isoproterenol has an IC50 of 0.016 microM and theophylline an IC50 of 74 microM, making the relaxant properties of these NO derivatives of potential pharmacological and physiological relevance.

Animals↗
PubMed1991

The impact of the Guidelines for a Healthy Diet of The Netherlands Nutrition Council on total and high density lipoprotein cholesterol in hypercholesterolemic free-living men.

To study the impact of dietary intervention on the plasma total and high density lipoprotein cholesterol (HDL cholesterol) levels in hypercholesterolemic men, the authors selected 80 male participants in a monitoring risk factor project carried out in Amsterdam, The Netherlands. These men had plasma total cholesterol levels of between 6.5 and 10.0 mmol/liter (between 251 and 387 mg/dl) and were randomly assigned to either the intervention (n = 39) or the control (n = 41) group. At the start of the intervention period, after 5 weeks, and after 26 weeks, both the intervention and the control groups were examined. This examination consisted of a measurement of height, weight, plasma total and HDL cholesterol, and a dietary interview. The intervention program consisted of a personalized dietary advice to the respondent, based on the report of the Netherlands Nutrition Council. The study took place between September 1987 and November 1988. Because of this intervention program, the plasma total and HDL cholesterol levels decreased. The difference in change in plasma total cholesterol between the intervention and control groups was 0.47 mmol/liter (18 mg/dl) after 5 weeks and 0.30 mmol/liter (12 mg/dl) after 26 weeks. For HDL cholesterol, a significant difference in change after 5 weeks disappeared after 26 weeks. The public health implications of the decrease in plasma total cholesterol are discussed.

Adult↗
PubMed1991

Dysphagia after Nissen fundoplication.

Nissen fundoplication is a commonly used antireflux operation. After this operation symptoms such as dysphagia, inability to belch and vomit, and gas bloating are frequently reported in the literature. In 32 patients who underwent Nissen fundoplication 3.5-18 years ago, postprocedure dysphagia was studied using conventional manometry and 24 h ambulatory pressure and pH recording. Our study indicates that dysphagia tends to decrease after surgery. Neither conventional nor ambulatory pressure recording revealed motor abnormalities that could be held responsible for the dysphagia. Therefore, the data do not support the concept that dysphagia is a major complication of Nissen fundoplication.

Adolescent↗
PubMed1991

On being led into temptation: "counterregulation" of dieters after smelling a "preload".

In the present study, it was found that dieters lost control over their food intake and "counterregulated" after merely smelling a "preload," while dieters without a "preload" were able to maintain control over their food intake. Nondieters, however, even ate marginally less after smelling a "preload" than they did in a no-preload condition. Apparently, actually breaking one's diet and such subsequent thoughts as "I've blown my diet, I might as well continue to eat" is not necessary for counterregulation to occur. The observation that merely smelling a "preload" is sufficient to produce "counterregulation" in dieters but not in nondieters challenges the explanatory power of the widely held cognitive explanation of experimental counterregulation in preloaded dieters. An explantation in terms of conditioning is put forward.

Adult↗
PubMed1991

A future role for loop ileostomy in colorectal surgery?

Thirty patients underwent a defunctioning loop ileostomy. Elective ileostomy was performed in 23 patients to protect a potentially vulnerable colorectal anastomosis and in one patient as a permanent faecal diversion for colonic atony. Six emergency loop ileostomies were performed; in four patients after colonic perforations and in two patients as a primary treatment secondary to colonic anastomotic leakage. Peri-operatively, none of the patients with an elective operation died. Four patients with an emergency operation, however, all died of irreversible peritoneal sepsis. Complications were a diversion colitis and an abdominal sepsis after anastomotic leakage in a second patient who required a re-operation. During follow-up (up to four years) one patient suffered from an episode of severe dehydration six months after operation. The ileal continuity was, without mortality, restored in 23 patients. Two patients had a wound infection with, in one of them, a late cicatricial hernia. In our experience, a defunctioning loop ileostomy is a relatively safe procedure and is, in our opinion, preferable to loop colostomy for temporary faecal diversion. The high mortality following emergency loop ileostomy reflects the bad prognosis of these patients and indicates the need for resection of the primary disease.

Emergencies↗
PubMed1991

Antibacterial activity of ciprofloxacin administered intravenously in a pharmacodynamic in vitro model.

The antibacterial activity of ciprofloxacin against Gram-positive and Gram-negative bacteria was evaluated in an in vitro model by simulating its pharmacokinetics following a single 100 or 200 mg administration intravenously. The one compartment open model described by Grasso and coworkers was used for these experiments. Ciprofloxacin concentrations in the model were reproduced by calculations based on the concentration-time curve in human volunteers as reported by Wise and others. The maximum reduction of viable cell count for Enterococcus faecalis and Staphylococcus aureus was from two-to three-orders of magnitude; for Pseudomonas aeruginosa and Enterobacter cloacae from four to seven orders. A rapid killing was recorded both for Gram-positive and Gram-negative bacteria, but the initial killing was more prolonged and more pronounced for the higher dosage. The last did not interfere with regrowth that occurred for all strains after eight hours.

Bacteria↗
PubMed1990

Clinical and non-clinical binges.

A study was conducted to determine if, and in what respects, clinical binges (reported by bulimic subjects) are different from non-clinical binges (reported by a non-clinical population). Furthermore, the study tested whether the DSM-III-R criteria and other variables that are retrospectively claimed to be defining characteristics indeed differentiate binges from non-binge eating episodes. Clinical binges appeared to differ from non-clinical binges as to amount of calories ingested and duration. With respect to subjective experience, clinical and non-clinical binges did not differ. The DSM-III-R criteria for binge eating discriminate clinical and non-clinical binges quite well from non-binges. With the addition of other seemingly important variables, binges are not discriminated better from non-binges than with the DSM-III-R variables alone. It is argued that the difference between pathological binge eating and non-clinical binge eating is mainly a matter of severity.

Adult↗
PubMed1990

Antibacterial activity of cefpodoxime proxetil in a pharmacokinetic in-vitro model.

The antibacterial activity of cefpodoxime proxetil was studied in an in-vitro model simulating doses of 100, 200 and 400 mg. Strains of Klebsiella spp. Proteus mirabilis, Escherichia coli, Streptococcus pyogenes, and Haemophilus influenzae were effectively reduced by a dose of 200 mg. While for Esch. coli no dose-activity relationship was observed--the maximal effect was achieved with a simulated dose of 100 mg--Staphylococcus aureus could be reduced effectively only by a simulated dose of 400 mg. The lower doses showed stepwise lower activities. Apart from broad spectrum beta-lactamases like SHV 2 or TEM 5 the presence of plasmid coded beta-lactamases in Esch. coli and H. influenzae did not affect the antibacterial activity of cefpodoxime proxetil. The results show that cefpodoxime was more active against Gram-negative bacteria than amoxycillin, and comparable activity to intramuscular cefotiam in the in-vitro model.

Amoxicillin↗
PubMed1990

Prospective evaluation of the effects of Nissen fundoplication on gastroesophageal reflux.

In 27 patients with uncontrollable gastroesophageal reflux, a modified Nissen fundoplication was performed. To investigate the long term effects of this procedure, 24-hour ambulatory esophageal pH monitoring was performed on three occasions: preoperatively, four weeks and two years postoperatively. Preoperative and postoperative symptoms were assessed. In 13 patients, fundoplication reduced reflux to zero (percentage of time pH less than 4, zero per cent), and in another 11 patients, reflux was reduced to a very low level (percentage of time pH less than 4, 0.75 +/- 0.21 per cent). The procedure failed in three patients, in whom both reflux symptoms and a pathologic pH profile persisted. No significant differences could be demonstrated between reflux variables in the early and late postoperative pH studies. Postoperatively, ten patients complained of heartburn or regurgitation, but pathologic reflux could only be demonstrated in three of these, and in two, there was macroscopic evidence of esophagitis. It is concluded that Nissen fundoplication abolishes or nearly abolishes gastroesophageal reflux in the majority of patients. Also, as in patients not operated upon, symptoms are unreliable indicators of the severity of gastroesophageal reflux after an antireflux procedure.

Adult↗
PubMed1989

A case of bulimia successfully treated by cue exposure.

In the present case-study, a 22-year-old female patient with a 7-year history of bulimia nervosa was treated by cue-exposure. During cue-exposure sessions the relationship between CS (stimuli associated with binge-eating behaviour) and UCS (the sensations related to the intake of binge food) was broken. As predicted, the patients' craving for food declined within as well as between cue exposure sessions and a radical decrease in the frequency of binge-eating persisted for at least nine months. Although during the therapy no explicit attention was paid to the patient's low mood and irrational self-talk, mood was improved and beliefs were less irrational after cue-exposure and at the follow-ups. The data suggest that cue exposure may be an effective part of the treatment of bulimia nervosa.

Adult↗
PubMed1989

Restrained eaters are rapidly habituating sensation seekers.

Several authors have pointed to similarities between eating disorders and addictive behaviors. In earlier studies, addicts were found to score high on the Sensation Seeking Scale (SSS) and to habituate rapidly to neutral stimuli. In this study, we found experimental support for an addiction model of eating disorders: restrained eaters also scored significantly higher on the Sensation Seeking Scale and also habituated significantly quicker to a series of neutral stimuli than unrestrained eaters. No clear evidence was found for the hypothesis that restrained eaters score lower on measurements of anxiety. It is hypothesized that rapid habituation promotes sensation seeking, which may be manifested in excessive consumption of either drugs or food. Restraint may be a strategy to prevent negative consequences of sensation seeking and excessive consumption. The model is related to earlier experimental findings.

Adult↗
PubMed1989

Does bingeing restore bulimics' alleged 5-HT-deficiency?

The co-occurrence of bingeing and depressed mood in bulimics may be explained by one pathogenic process: hyposerotonergic functioning. A relatively high carbohydrate intake improves mood and raises 5-HT level. Therefore, several authors suggested that the carbohydrate intake during binges may be a form of self-medication to compensate for bulimics' alleged hyposerotonergic functioning, thereby improving mood. This view, in which bingeing compensates for central 5-HT deficiencies, assumes that bulimics' binges contain relatively more carbohydrates than bulimics' non-binge-eating episodes. In the present study, bulimics' binge-eating and non-binge-eating episodes were compared as to macronutrient and calorie intake. However, no support was found for the hypothesis that binge-eating enhances brain serotonin.

Adult↗
PubMed1989

Food consumption patterns in the 1960s in seven countries.

At the end of the 1950s the Seven Countries Study was designed to investigate the relations between diet and cardiovascular diseases. Sixteen cohorts were selected in Finland, Greece, Italy, Japan, The Netherlands, United States, and Yugoslavia. During the 1960s food consumption data were collected from random samples of these cohorts by use of the record method. In Finland the intake of milk, potatoes, edible fats, and sugar products was very high. A similar but lower intake pattern was observed in The Netherlands. Fruit, meat, and pastry consumption was high in the United States; cereal and alcoholic drink consumption was high in Italy; and bread consumption high in Yugoslavians except for those in Belgrade. In Greece the intake of olive oil and fruit was high and the Japanese cohorts were characterized by a high consumption of fish, rice, and soy products. These differences in food consumption patterns have lessened during the past 25 y.

Adult↗