PubMed Health⌕ Search

Biomedical subjects

R de Graaf

Publications and source records attributed to R de Graaf.

At least 55 records · Page 3Linked to original sources
PubMed1996

Clinical implications of the rise and fall of prostate specific antigen after laser prostatectomy.

OBJECTIVE: To characterize the serum kinetics of prostate specific antigen (PSA) after visual laser ablation of the prostate (VLAP). PATIENTS AND METHODS: The PSA values of 45 patients were measured at 24 h and at 1, 4, 12, 26 and 52 weeks after VLAP and the changes assessed in relation to symptom scores, urinary flow rates and prostate size. RESULTS: After an initial rise immediately after VLAP, the serum PSA level declined. At 24 h, the PSA value reached a mean level 23 times higher than the PSA level before VLAP and then took a mean of 78 days to reach a new baseline. The mean decrease of the subsequent baseline value relative to that before treatment was 1.7 ng/mL. The prostatic size and energy applied correlated positively with the rise in PSA 24 h after VLAP. The rise in maximal urinary flow after VLAP, the decrease in the symptom score and residual urine volume did not correlate with the rise in PSA level 24 h after VLAP or with the time to reach a value halfway between the level at 24 h and the new baseline value. CONCLUSIONS: The pattern of the increase in serum PSA level and decline after VLAP was not predictive of the clinical outcome of therapy.

Humans↗
PubMed1996

Segmentation of heterosexual prostitution into various forms: a barrier to the potential transmission of HIV.

The results of an earlier Dutch study on prostitutes' clients, interviewed face-to-face, were cross-validated by means of telephone interviews, which both guaranteed anonymity and produced a larger sample of respondents (n = 559). Depending on their preference and financial resources, they had visited different types of prostitution; but about half of them had restricted themselves to one type. Inconsistent use of condoms was reported by 14% of the clients who had had vaginal or anal intercourse. Condoms were most frequently used in clubs, brothels and window prostitution, and least often in street, home and escort prostitution; in the last two sorts especially not with regular prostitutes. Whether or not prostitutes came from non-Western countries had no influence on protective behaviour of these clients. The formation of networks between different sorts of prostitution, through unsafe sexual contacts in two or more sorts, involved only 3% of respondents. Thus, prostitution in The Netherlands should be seen as a number of sparsely-connected networks rather than as a single network. The formation of networks between prostitution and the population at large is made possible by the 10% of the respondents who had had unsafe contacts with both commercial and private partners.

Adult↗
PubMed1996

The effects of early and late preterm birth on brainstem and middle-latency auditory evoked responses in children with normal neurodevelopment.

In preterm and term infants, brainstem and middle latency auditory evoked responses (ABR and MLR) were obtained at 40 and 52 weeks conceptional age (CA) and at 5 years of age. A neurological and neuropsychological evaluation was performed at 5 years of age. To study the effect of preterm birth on the maturation of the ABR and MLR, the preterm infants were divided into early and late preterm groups. Only children with a normal neurodevelopmental outcome at 5 years of age were entered into the study. For ABR, the late preterm group showed significantly longer mean latencies IIc, III, V, and Vc when compared with the term group at 52 weeks CA. There was a trend to longer ABR latencies I in the early preterm group compared with the term group. At 52 weeks CA, the late preterm group showed longer mean interpeak latencies III-I and V-I when compared with the term as well as the early preterm group. At 5 years, the late preterm group showed significantly longer mean ABR latencies IIc and III when compared to the early preterm group. For MLR, the early preterm group showed significantly longer mean latencies of MLR component PO when compared with the term group at 40 weeks CA. At 52 weeks, the late preterm group also had longer mean MLR latencies P0 than the term group. At 5 years of age, the term group showed higher mean peak-to-peak amplitudes Na-P0 than the early as well as the late preterm group. To a large extent, the ABR results support the hypothesis that middle ear effusions in combination with retarded myelination of the central auditory pathway are responsible for the ABR differences found between term and preterm infants with a normal neurodevelopmental outcome at 5 years of age. The longer latencies and interpeak latencies found in late preterm infants when compared with early preterm infants might be explained by an augmented vulnerability of the auditory pathway between 30 and 34 weeks CA. The MLR differences found between term and preterm infants might be explained by a difference in the maturation of primary and nonprimary MLR components.

Auditory Cortex↗
PubMed1996

Purine enzyme activities in recent onset rheumatoid arthritis: are there differences between patients and healthy controls?

OBJECTIVE: Purine enzyme activities may predict the effectiveness of azathioprine treatment and be associated with increased deaths from infectious diseases. In rheumatoid arthritis, patients show variable responses to azathioprine and a higher percentage of death is caused by infections. The aim of the study was to investigate possible rheumatoid arthritis associated abnormalities of purine enzyme activities by measuring several of these enzymes in patients with recent onset rheumatoid arthritis before treatment with disease modifying antirheumatic drugs or prednisone. METHODS: 23 patients with recent onset rheumatoid arthritis and 28 healthy controls were studied. Activities of the enzymes 5'-nucleotidase, purine nucleoside phosphorylase (PNP), hypoxanthine guanine phosphoribosyltransferase (HGPRT), and thiopurine methyltransferase (TPMT) were measured. Assessment of disease activity and blood sampling for routine measurements and HLA typing were done simultaneously. RESULTS: Purine enzyme activities did not differ between patients and healthy controls. Enzyme activities had no significant relations with indices of disease activity or rheumatoid factor titre or with the rheumatoid arthritis associated HLA types. Activity of 5'nucleotidase decreased with age (P < or = 0.05) and was lower by about 27% (P = 0.007) in males than in females. CONCLUSIONS: In rheumatoid arthritis patients, neither the variability in azathioprine effectiveness nor the increased death rate from infections can be explained by pre-existing abnormalities in the activities of the purine enzymes 5'-nucleotidase, PNP, HGPRT, or TPMT at an early stage of the disease, before disease modifying antirheumatic drugs or prednisone treatment. Besides adjustment for age, results of studies involving purine 5' nucleotidase activity should also be adjusted for sex.

Adult↗
PubMed1995

Purine enzyme activities in peripheral blood mononuclear cells: comparison of a new non-radiochemical high-performance liquid chromatography procedure and a radiochemical thin-layer chromatography procedure.

Purine enzyme activities are usually assayed by radiochemical procedures and often TLC is part of the separation method. In screening patients with rheumatic diseases, these procedures have shown disadvantages like a relatively large coefficient of variation (C.V.) and time-instability. We describe a non-radiochemical reversed-phase HPLC micro-method with UV detection for measurement of activities of purine 5'-nucleotidase (5'NT; EC 3.1.3.5), purine nucleoside phosphorylase (PNP; EC 2.4.2.1) and hypoxanthine guanine phosphoribosyltransferase (HGPRT; EC 2.4.2.8) in human peripheral blood mononuclear cells (PBMC). The HPLC procedure is compared with the radiochemical TLC procedure by testing both with a 5'NT and a PNP assay. Reproducibility is tested with 14 healthy controls in each procedure. Short-term and long-term time-stability is tested by comparing enzyme activities measured immediately after preparation of the PBMC (week 0) with those found after freezing and storage at -20 degrees C for a maximum of 10 weeks. The HPLC procedure is preferable to the radiochemical TLC procedure because it shows significantly better reproducibility and better time-stability and in addition is non-radiochemical and less time-consuming.

Adult↗
PubMed1995

Professional HIV risk taking, levels of victimization, and well-being in female prostitutes in The Netherlands.

Professional HIV risk taking (nonconsistent condom use with clients) of female prostitutes in The Netherlands is addressed within the context of (early) experiences with abuse, well-being, coping behavior, job satisfaction, and financial need. Data were gathered from 127 female prostitutes on condom use, financial need, and professional attitude, and on experiences with violence and abuse, physical complaints, psychosocial problems, and coping responses. Violent traumatic experiences were found to relate to more severe complaints and problems, and a higher frequency of emotion-focused coping strategies. A risk-taking protection style (as opposed to consistent condom use and selective risk taking) appeared to be associated with more severe experiences with violence, both in childhood and in adult life, with more frequent dissociation as a coping behavior, and with more psychosomatic complaints. Of all the relationships found, more severe experiences with violence on the job were most strongly related to a higher professional HIV risk.

Adaptation, Psychological↗
PubMed1995

Alcohol and drug use in heterosexual and homosexual prostitution, and its relation to protection behaviour.

To assess the prevalence and effects of alcohol and drug use in heterosexual and homosexual commercial contacts, and the relationship between their use and unsafe sexual behaviour, 127 female prostitutes, 27 male prostitutes, 91 clients of female prostitutes and 24 clients of male prostitutes were interviewed face-to-face with the help of a semi-structured questionnaire. The respondents were living or working in different parts of The Netherlands. Alcohol and drug use was found to be relatively common among prostitutes. This was also so for the use of alcohol by clients, though to a lesser extent. Prostitutes' consumption varied widely according to the type of prostitution they were employed in. Those meeting their clients in clubs or bars reported the highest consumption of alcohol; hard drugs were used predominantly by street prostitutes. It appears that the main effects of alcohol and drug use are on how the individual experiences working as, or calling on, a prostitute, the social interaction between the two parties, and the sexual contact itself. The common assumption that drinking alcohol has negative effects on condom use was not borne out; though female prostitutes working under the influence of drugs were significantly more likely to report unsafe sex. The degree to which commercial partners were judged to be under the influence of alcohol or drugs was not found to bear upon the frequency of respondents' condom use. For those prostitutes who use hard drugs, this use plays an important role in their engaging in unsafe sexual activities. Prevention activities should focus especially on this group, and should take into account the role of such drug use.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Contextual and interactional factors influencing condom use in heterosexual prostitution contacts.

The protection behavior of prostitutes and prostitutes' clients has been studied from a contextual and an interactional point of view. Different protection styles (subject's cognitive and behavioral position regarding condom use) have been identified in both prostitutes (N = 119) and clients (N = 91). Risk-taking prostitutes were found to have the least favorable working conditions, to have the highest financial need, to have the lowest levels of well-being and job satisfaction and to have been victimized more often than consistent condom users and selective risk-taking prostitutes. Consistent condom users among the clients were found to be better educated, to have a less strong external Health Locus of Control, to evaluate condoms and visiting prostitutes more positively, and prostitutes less negatively, and to have more fear of AIDS than non-consistent condom using clients. Various protection styles were found to be thoroughly intertwined with different interaction scenarios. Four different interaction scenarios (a standard, a romantic, a friendship and a fighting scenario) with a different chance of condom use are set forth. It is shown that the scenario approach gives good insight into the process by which unsafe sex in commercial contacts comes about. For both actors, the context and the meaning of prostitution influence the way they play the game. The interaction and its outcome in their turn reinforce their attitudes towards prostitution. Implications for AIDS prevention are discussed.

Adult↗
PubMed1994

Male prostitutes and safe sex: different settings, different risks.

Twenty-seven male prostitutes were interviewed extensively about their work and considerations relating to safe sex with clients. Important differences were found between street prostitutes and those working at home. Street-workers were more likely to be using hard drugs, to have a heterosexual preference, to have no other occupation, to have more clients, but less steady ones, and to have a more negative working attitude. Sexual techniques most often practised were manual and oral contact; however, most prostitutes also practised either insertive or receptive anal intercourse. Homosexual male prostitutes reported more receptive anal intercourse than did their heterosexual male colleagues; but no such differences were found in insertive anal intercourse. Prostitutes were most likely to have had anal intercourse with steady clients, with clients whom they trusted regarding condom use, or with clients they felt sexually attracted to; and also when in dire need of drugs. Of those who had practised anal intercourse in the previous year, a minority had not consistently used condoms. The same factors that encourage anal intercourse also appear conducive to unprotected intercourse.

Adolescent↗
PubMed1994

Purine enzymes in rheumatoid arthritis: possible association with response to azathioprine. A pilot study.

OBJECTIVE: To study the possible association of purine enzyme activities with response to azathioprine (AZA) treatment in rheumatoid arthritis (RA) and their correlation with parameters of disease activity. PATIENTS AND METHODS: Lymphocyte activities of hypoxanthine-guanine phosphoribosyl-transferase (HGPRT), adenine phosphoribosyltransferase (APRT), purine nucleoside phosphorylase (PNP) and 5'-nucleotidase (5NT), and erythrocyte activities of thiopurine methyltransferase (TPMT) were measured in 14 healthy controls and 36 patients with RA. Eight patients had not previously been treated with AZA. Response to AZA therapy in 28 patients, determined in a prospective trial, was considered good in nine (group 1), insufficient in seven (group 2). In 12 patients AZA was withdrawn because of adverse reactions (group 3). Disease activity parameters were obtained simultaneously with purine enzyme measurements. Purine enzyme levels in the different groups were compared. RESULTS: Levels of 5NT activity were significantly lower in patients with RA than in healthy controls. PNP activity was higher in patients with RA not using prednisone compared with those who did and healthy controls. No clear correlation between purine enzyme levels and disease activity parameters was found. 5NT activities were significantly higher in group one than in group three (p = 0.012; alpha = 0.017), and almost significantly higher than in group two (p = 0.03; alpha = 0.017). CONCLUSIONS: The results indicate that purine enzyme activities in patients with RA differ from healthy controls, are associated with the outcome of AZA treatment and seem not to be associated with disease activity. Our findings may offer a clue to predict the response to AZA therapy in RA.

5'-Nucleotidase↗
PubMed1993

Prognosis of unsuspected but completely resectable N2 non-small cell lung cancer.

Of 111 patients with non-small cell lung cancer without clinically evident N2 disease 95 underwent mediastinoscopy between 1975 and 1985. In 63 cases mediastinoscopy was positive and in 32 negative. The patients with a positive mediastinoscopy were considered to have inoperable disease. Their 3- and 5-year survival rates were 5% and 0%, respectively. The patients with a negative mediastinoscopy and 16 patients in whom no mediastinoscopy was performed because of a peripheral tumor underwent operation. They underwent complete tumor resection and mediastinal lymph node dissection. Unsuspected N2 disease was found. Their 3- and 5-year survival rates were 19% and 10%, respectively. The better survival rate in the operated group was statistically significant and mainly due to a better survival of the lobectomy group. Multiple regression analysis showed no favorable prognostic factors in the nonoperated group, but in the operated group lobectomy and central location of the tumor significantly improved the prognosis. We conclude that patients with unsuspected stage IIIa non-small cell lung cancer discovered at thoracotomy benefit from complete tumor resection and mediastinal lymph node dissection, especially if the resection can be confined to lobectomy and if the tumor is located centrally.

Adult↗
PubMed1993

Hereditary neuropathy with liability to pressure palsies: a clinical, electroneurophysiological and morphological study.

Clinical, electroneurographic and myographic studies were performed on 99 patients of 13 families having hereditary neuropathy with liability to pressure palsies (HNPP) and on 116 relatives. Diagnosis was confirmed in all families by a nerve biopsy of the index case. Large focal myelin thickenings (tomacula) were found in nerve biopsies of affected persons, whether or not pressure palsies had occurred. By using three electroneurographical parameters it was possible to discriminate between asymptomatic patients and unaffected relatives. Complaints sometimes mentioned in literature as being associated with HNPP such as low back pain, brachialgia and short lasting paraesthesia are not related to HNPP. The hereditary transmission is autosomal dominant with total penetration but variable expression.

Adolescent↗
PubMed1993

The effectiveness of condom use in heterosexual prostitution in The Netherlands.

OBJECTIVES: To assess the extent to which condoms are used effectively in commercial heterosexual intercourse. Data on the number of condoms that had broken or slipped off, the sexual technique during which this had occurred and the perceived cause of failure were collected. The use of non-water-soluble lubricants and non-fortified condoms during anal intercourse, and the demand for a greater variety of condom sizes were also examined. SUBJECTS AND METHODS: One hundred and twenty-seven female prostitutes and 91 male clients from different parts of The Netherlands were interviewed face-to-face between July 1990 and March 1991. RESULTS: Of those who used condoms during vaginal intercourse, 49% of the prostitutes had experienced condom breakage in the previous 6 months, and 16% of the clients in the previous 12 months. The breakage rate was 0.8% for prostitutes and 1.5% for clients. Condom quality was seldom reported as the cause; breakage was generally attributed to human factors, such as rough or prolonged intercourse, incorrect handling of the condom or the use of insufficient lubricant. Prostitutes also identified penis size as a cause. Condoms slipping off before or after ejaculation was reported less frequently than breakage. Thirteen per cent of clients and 36% of prostitutes expressed a need for either smaller or larger condoms. Of the prostitutes, 9% used oil or vaseline as a lubricant. CONCLUSIONS: In view of the low rate of condom failure in heterosexual prostitution in The Netherlands, the potential spread of HIV by this means is small. The use of a greater variety of condom sizes may further reduce the failure rate. Few prostitutes remain ignorant about the adverse effects of oil-based lubricants on condoms.

Condoms↗
PubMed1992

The effect of preterm birth on brainstem, middle latency and cortical auditory evoked responses (BMC AERs).

Recent studies on the maturation of auditory brainstem evoked responses (ABRs) present conflicting results, whereas only sparse reports exist with respect to the maturation of middle latency auditory evoked responses (MLRs) and auditory cortical evoked responses (ACRs). The present study reports the effect of preterm birth on the maturation of auditory evoked responses in low risk preterm infants (27-34 weeks conceptional age). The ABRs indicate a consistent trend towards longer latencies for all individual ABR components and towards longer interpeak latencies in preterm infants. The MLR shows longer latencies for early component P0 in preterm infants. The ACRs show a remarkable difference between preterm and term infants. At 40 weeks CA the latencies of ACR components Na and P2 are significantly longer in term infants, whereas at 52 weeks CA the latencies of the same ACR components are shorter in term infants. The results support the hypothesis that retarded myelination of the central auditory pathway is partially responsible for differences found between preterm infants and term infants with respect to late ABR components and early MLR component P0. Furthermore, mild conductive hearing loss in preterm infants may also play its role. A more complex mechanism is implicated to account for the findings noted with respect to MLR component Na and ACR components Na and P2.

Evoked Potentials, Auditory↗
PubMed1992

Maturation of mitochondrial and other isoenzymes of creatine kinase in skeletal muscle of preterm born infants.

We studied pre- and postnatal changes in total creatine kinase (CK) activity, mitochondrial creatine kinase (Mi-CK) activity and immunochemical reactivity with anti-Mi-CK antibodies in skeletal muscle specimens from 12 infants, 10 of them preterm born, after a pregnancy varying between 28 and 40 weeks. Our results demonstrate that Mi-CK is present in fetal human quadriceps muscle and that the specific activity of Mi-CK increases during prenatal development from week 28 to 40 by a factor about two. Generally, adult levels have not been reached at birth, indicating a further postnatal increase of the activity of the enzyme. The Mi-CK protein content also increases during prenatal development. These results suggest that in human skeletal muscle the expression and accumulation of Mi-CK starts at mid-gestation, later than is known to occur for cytosolic CK.

Citrate (si)-Synthase↗
PubMed1991

Familial selective IgA deficiency with circulating anti-IgA antibodies: a distinct group of patients?

Two families were investigated in which the mothers had selective IgA deficiency and circulating class-specific anti-IgA antibodies. Both gave birth to two children who were found to be IgA deficient. Three of these children developed anti-IgA antibodies before puberty. In vitro immunoglobulin production studies performed in the children of both families revealed an IgA B cell defect combined with IgA-specific excessive T suppressor function in all four. The mechanisms by which transplacental passage of maternal anti-IgA antibodies could have interfered with the developing IgA system in the offspring are discussed.

Adult↗