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Biomedical subjects

J W Maas

Publications and source records attributed to J W Maas.

At least 19 recordsLinked to original sources
PubMed1999

Fertility potential of individual sperm donors.

OBJECTIVE: To study the fertility potential of individual semen donors with ejaculates of optimal as compared to suboptimal quality. METHODS: 363 semen donations were obtained from 11 donors between January 1993 and September 1997. 270 samples were cryopreserved and 1,399 straws obtained from 120 ejaculates were used in 495 insemination cycles. RESULTS: 52 pregnancies were achieved in 128 recipients (40.6%). No significant differences were found between donors of high fecundability and those of low fecundability regarding sperm parameters. The mean donor fecundability index was 10.5%. The optimal and suboptimal samples yielded similar results. Donors with suboptimal semen quality had an increased number of samples rejected after thawing. CONCLUSION: Traditional semen analysis parameters do not differentiate high from low fecundability donors. Suboptimal results of the semen analysis should not exclude potential donors from an artificial insemination donor (AID) program.

Cryopreservation↗
PubMed1999

The chick embryo chorioallantoic membrane as a model to investigate the angiogenic properties of human endometrium.

The chick embryo chorioallantoic membrane (CAM) is an established in vivo angiogenesis assay. The aim of our study was to assess the angiogenic properties of endometrium and to quantitate the vascular response in an accurate way. Samples of proliferative endometrium (n = 17) and control mouse skin tissue (n = 8) were explanted onto the CAM at day 10 of incubation. Additional controls consisted of normal unmanipulated CAM (n = 12). Four days after grafting, photographs of the explant and the surrounding area were taken in ovo to measure the vascular density index (VDI). The VDI is a stereological estimate of vessel number and length, which was obtained by counting the intersections of vessels with a circular grid superimposed on a computerized image. Endometrium caused a significant increase in VDI as compared to both unmanipulated CAM (p < 0.001) and skin tissue as a control (p < 0.007). The intra-observer variability was 5.2%. This study demonstrates that the CAM assay is a suitable model to assess the angiogenic properties of endometrium. Furthermore, it allows detailed quantitation of the vascular response in an objective and reproducible way. Our findings suggest the CAM to be a promising model to study the role of angiogenesis in both normal human endometrium and diseases involving the endometrium.

Allantois↗
PubMed1998

Apoptosis of central and peripheral neurons can be prevented with cyclin-dependent kinase/mitogen-activated protein kinase inhibitors.

Previous studies have indicated that certain members of the cyclin-dependent kinase/mitogen-activated protein kinase superfamily are involved in apoptosis of neuronal cells. Here, we have examined programmed cell death induced by withdrawal of neurotrophic support from CNS (rat retinal) and PNS (chick sympathetic, sensory, and ciliary) neurons. All four neuron types were equally rescued by the purine analogues olomoucine and roscovitine. Olomoucine inhibits multiple cyclin-dependent and mitogen-activated protein kinases with similar potency. Roscovitine is a more selective cyclin-dependent kinase inhibitor; but, so is butyrolactone I, which did not prevent retinal ganglion cell death. The specific p38MAPK inhibitor SB-203580 did not prevent apoptosis in retinal ganglion cells. Death of these cells in the absence of neurotrophic factors was accompanied by morphological changes indicative of apoptosis, including nuclear condensation and fragmentation. Treatment with olomoucine or roscovitine not only prevented these apoptotic changes in retinal ganglion cells but also blocked neurite outgrowth. The survival-promoting activity of olomoucine correlated with its in vitro IC50 for c-Jun N-terminal kinase-1 and its potency to repress c-jun induction in live PC12 cells. Roscovitine was more potent in rescuing neurons than in inhibiting Jun kinase. Thus, the antiapoptotic action of roscovitine might be due to inhibition of additional kinases.

Animals↗
PubMed1997

Schizophrenia, psychosis, and cerebral spinal fluid homovanillic acid concentrations.

Neuroleptic drugs block brain dopamine receptors and are effective in treating psychoses of diverse origins. This finding has become a cornerstone of the dopamine theory of schizophrenia, but clinical studies relating schizophrenia, per se, to brain dopamine metabolism have ranged from controversial to negative. This article presents new evidence that cerebrospinal fluid levels of the dopamine metabolite homovanillic acid are related to the severity of psychosis in schizophrenia. These results support the concept that homovanillic acid levels in cerebrospinal fluid vary as a function of psychosis rather than being related to the diagnosis of schizophrenia per se.

Adult↗
PubMed1997

Pregnancy rate following normal versus abnormal hysterosalpingography findings: a meta-analysis.

A computerized Medline search was conducted, to assess the prognostic value of hysterosalpingography (HSG) and the probability of pregnancy after normal versus abnormal HSG findings. A total of 13 studies turned out to be eligible, reporting on 3,277 women. 15% of women with an abnormal HSG and 32% of women with a normal HSG achieved pregnancy. Sensitivities and specificities of the studies were heterogeneous. The pooled odds ratio was 3 (95% CI: 2.3-3.4). Its ROC Curve shows that, at the operating point yielding the lowest number of misclassifications, a sensitivity of 63% and a specificity of 62% is achieved. Seven studies reported unilateral and bilateral obstruction. Odds ratios were 2(95% CI: 1.5-2.6) and 19(95% CI: 7.5-46.5) respectively. So, overall, HSG has a low prognostic value, the outcome of HSG adds little to predicting the occurrence of pregnancy. However, when HSG shows bilateral obstruction, the chance of getting pregnant is only minimal.

Fallopian Tube Diseases↗
PubMed1996

Catecholamines in attention-deficit hyperactivity disorder: current perspectives.

OBJECTIVE: To provide an update on the "catecholamine hypothesis" of attention-deficit hyperactivity disorder (ADHD). METHOD: Recent work examining the measurement of the norepinephrine, epinephrine, and dopamine systems in ADHD and normal subjects is reviewed and discussed in the context of recent neuroimaging and animal studies. RESULTS: While data clearly indicate a role for all three of the above neurotransmitters in ADHD, a hypothesis suggesting "too much" or "too little" of a single neurotransmitter will no longer suffice. The central norepinephrine system may be dysregulated in ADHD, such that this system does not efficiently "prime" the cortical posterior attention system to external stimuli. Effective mental processing of information involves an anterior "executive" attention system which may depend on dopaminergic input. The peripheral epinephrine system may be a critical factor in the response of individuals with ADHD to stimulant medication. CONCLUSION: A multistage hypothesis is presented which emphasizes the interaction of norepinephrine, epinephrine, and dopamine in modulation of attention and impulse control.

Attention Deficit Disorder with Hyperactivity↗
PubMed1995

[Subfertility in South Limburg: calculation of incidence and appeal for specialist care].

OBJECTIVE: To estimate the prevalence of subfertility in a region of the Netherlands clearly defined as to medical care. DESIGN: Descriptive. SETTING: Six regional hospitals and one university medical centre. METHODS: Prospective registration of all 1060 new patients attending one of the seven hospitals and complaining of subfertility, in 1992. RESULTS: After exclusion of patients living outside the health care region, and/or having pursued pregnancy for less than 12 months, and/or having visited one of the other hospitals (with the same complaint) before, 536 patients remained. For this region, with a population of 641,876 at the time of the study, we estimated the cumulative incidence of subfertility in 1992 to be 10.4% (95% confidence interval: 9.6-11.2%). Between 14 and 16.5% of couples sought specialist medical care for their fertility problem. CONCLUSION: Between 14 and 16.5% of couples sought specialist medical care for fertility problems during their reproductive life. More than 10 percent fulfilled the criteria for subfertility.

Adolescent↗
PubMed1995

Clonidine plus haloperidol in the treatment of schizophrenia/psychosis.

Because of the evidence for increased norepinephrine (NE) production in psychotic patients, we studied the effects of combining the alpha 2-adrenergic agonist clonidine with haloperidol for the treatment of schizophrenic psychosis. Twelve hospitalized schizophrenic patients were taken off their antipsychotic medication for 2 to 4 weeks before double-blind treatment with haloperidol (20 mg/day) combined with either clonidine or placebo. The group receiving clonidine was significantly more improved on the thought disorder subscale of the Brief Psychiatric Rating Scale (p = 0.02). The groups differed initially in the level of negative symptoms, but not controlling for this difference statistically by analysis of covariance did not change the finding with regard to the superiority of combining clonidine with haloperidol. We conclude that larger treatment trials of combining haloperidol with clonidine are warranted.

Adrenergic alpha-Agonists↗
PubMed1994

Depressive mania versus agitated depression: biogenic amine and hypothalamic-pituitary-adrenocortical function.

The existence of mixed affective states challenges the idea of specific biological abnormalities in depression and mania. We compared biogenic amines and hypothalamic-pituitary-adrenocortical (HPA) function in mixed manic (n = 8), pure manic (n = 11), agitated bipolar depressed (n = 20), and nonagitated bipolar depressed (n = 27) inpatients (Research Diagnostic Criteria). Mixed manics met Research Diagnostic Criteria for primary manic episodes and also met criteria for major depressive episodes except for duration. The norepinephrine metabolite methoxyhydroxy phenthylene glycol (MHPG) was higher in cerebrospinal fluid from mixed manic than from agitated depressed patients, consistent with differences previously reported between the overall samples of depressed and manic patients. Similarly, patients in a mixed state had higher urinary excretion of norepinephrine (NE) and elevated output of NE relative to its metabolites. HPA activity was similar in mixed manic and agitated depressed patients. These data suggest that mixed manics combine certain biological abnormalities considered to be characteristic of mania and of depression.

Adult↗
PubMed1994

Drug-induced actions on brain neurotransmitter systems and changes in the behaviors and emotions of depressed patients.

Despite cumulative evidence that the tricyclic drugs result in significant changes in the functioning of brain serotonergic (5-HT) and nordrenergic (NE) systems, such changes have not been found to be associated with recovery from depression. Based upon evidence that the 5-HT and NE systems were associated with different emotions, it was hypothesized that changes in these systems were associated with different components of behavior in drug-responsive patients and not with changes in the "whole" disorder. Findings from this multihospital study of 104 unipolar and bipolar depressed patients showed early drug-associated reductions in anxiety and hostility in treatment responders to precede changes in motor retardation and depressed mood. Adopting this approach of looking for relationships between changes in components of major depression and changes in neurotransmitter system function, decreases in 5-HT and NE metabolite concentrations in cerebrospinal fluid (CSF) in patients treated with tricyclics, were found to be correlated with changes in specific behaviors. Results indicated the following: (1) drug-induced changes in the 5-HT system to be associated with mood aspects, notably anxiety, and depressed mood; changes in NE primarily with the psychomotor, secondarily with the mood components of the depressed state; (2) the pattern of relationships between changes in 5-HT and in mood in the unipolar was different than that in the bipolar subtype. The results indicate that in determining the relationships of biochemical changes to behavioral ones, that it is important to take into account the type of depression (bipolar or unipolar), as well as examining individually and over time those components that make up the disorder of depression. These results support evidence that tricyclics have multiple behavioral actions, that response is mediated through changes in specific behaviors and that this approach warrants further application in prospective studies of antidepressant drug mechanisms and their therapeutic actions.

Amitriptyline↗
PubMed1994

Urinary catecholamines in attention-deficit hyperactivity disorder with and without comorbid anxiety.

OBJECTIVE: To determine whether there are differences in noradrenergic or adrenergic functioning in children with attention-deficit hyperactivity disorder (ADHD) with and without anxiety. METHOD: ADHD children with and without a comorbid overanxious (ANX) disorder were compared to each other and to normal controls in terms of 2-hour urinary excretion of norepinephrine (NE), epinephrine (EPI), and their metabolites. All subjects performed a fixed series of mentally stressful tasks during the collection period. RESULTS: Children with ADHD, regardless of comorbid anxiety, excreted more normetanephrine (NMN), the chief extracellular metabolite of NE, than controls, as well as more vanillylmandelic acid. Children with ADHD alone had lower NE/NMN and EPI/metanephrine ratios compared to controls. Children with ADHD/ANX excreted more EPI than ADHD children without anxiety. CONCLUSIONS: Children with ADHD may have a higher tonic activity of the noradrenergic system than controls, while children with comorbid ADHD/ANX may be differentiated from those with ADHD alone by higher adrenergic activity.

Anxiety Disorders↗
PubMed1993

Acute effects of neuroleptics on unmedicated schizophrenic patients and controls.

Acute administration of haloperidol (0.2 mg/kg) produced many more side effects in normal controls than in unmedicated schizophrenic patients. Prior to the neuroleptic challenge, both groups were on the peripheral monoamine oxidase inhibitor, debrisoquin, for at least 1 week, in order to enhance the relative contribution of CNS catecholamine metabolites to those measured in both plasma and urine. The patient group had higher plasma levels of methoxyhydroxyphenylglycol (MHPG) and homovanillic acid (HVA) and higher urinary MHPG output than controls, but there were no effects of haloperidol challenge, compared to placebo challenge. In both groups there were significant declines in plasma HVA levels from 8:30 AM to 12 NOON. These declines were unaffected by the haloperidol challenge. Explanations for the marked differences in behavioral effects of haloperidol on patients and controls include the possibility that dopamine receptor numbers were increased in the brains of the schizophrenic patients.

Adult↗
PubMed1993

Effects of fire ant venom alkaloids on platelet and neutrophil function.

About 95% of venom of the imported fire ant Solenopsis invicta is composed of dialkyl piperidines. These alkaloids produce a distinct pustule at the site of injection. The formation of this pustule may involve the activation of platelets and neutrophils. The purpose of this paper was to characterize the effects of fire ant venom alkaloids (FAVA) on certain physiological and biochemical functions of human platelets and neutrophils. In platelets, FAVA caused a rise in intracellular [Ca2+], secretion of dense granules as measured by ATP release, and aggregation as measured by light transmission through a suspension of platelets. Aggregation response was less complete with FAVA than with thrombin or PAF. However, secretion response was greater with FAVA than thrombin. One of our most significant findings was that pretreatment of platelets with subthreshold concentrations of FAVA produced enhanced PAF-induced increase in [Ca2+]cyt, suggesting that synergism between the two agonists might play an important role in the physiological response to FAVA. In neutrophils, FAVA produced a rise in intracellular [Ca2+] and aggregation, although the responses were more moderate than those observed in platelets. These results suggest that FAVA activation of platelets and neutrophils may occur in vivo as a response to stings by red fire ants.

Adenosine Triphosphate↗
PubMed1993

Studies of catecholamine metabolism in schizophrenia/psychosis--I.

Acutely psychotic schizophrenic patients not taking antipsychotic medications and control subjects were studied before and during treatment with debrisoquin (DBQ), an inhibitor of monoamine oxidase, which does not penetrate into brain. Homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) were measured in plasma, urine, and cerebrospinal fluid (CSF). Significant differences between patients and control subjects were more easily discerned during treatment with DBQ. In patients, HVA was increased in plasma but not in urine or CSF, although MHPG was increased in all three fluids. There were many significant correlations between plasma MHPG and HVA levels and clinical ratings of psychoticism. Plasma MHPG correlated positively with both the severity of positive and negative symptoms and plasma HVA correlated only with positive symptom severity. These data suggest that both dopamine and norepinephrine (NE) metabolism are disturbed in acutely psychotic schizophrenic patients; disturbed NE metabolism may relate to negative symptoms as well.

Adult↗
PubMed1993

Studies of catecholamine metabolism in schizophrenia/psychosis--II.

Acutely psychotic schizophrenic patients were maintained on debrisoquin (DBQ) throughout 5 weeks of treatment with haloperidol. Treatment with haloperidol caused initial increases in urinary homovanillic acid (HVA) output that returned toward baseline by the 5th week. During haloperidol treatment, plasma levels of HVA tended to decrease, concurrent with increased renal clearance of HVA. Plasma 3-methoxy-4-hydroxyphenylglycol (MHPG) levels and urinary MHPG output both decreased over the course of treatment. The differences in HVA and MHPG metabolism suggest differential effects of treatment on dopamine and norepinephrine systems. Neuroleptic treatment also abolished the marked morning decreases in plasma HVA concentrations (reported in part I).

Adult↗