[Towards personalized treatment with clozapine]. / Op naar een gepersonaliseerde clozapinebehandeling.

BACKGROUND: Clozapine is the most effective treatment for people with treatment-resistant schizophrenia. However, it is prescribed less often than guidelines indicate. AIM: To personalize clozapine treatment, we investigated the efficacy of clozapine as first- or second-line treatment and investigated whether there are factors that were associated with efficacy and side effects. METHOD: We collected a unique cohort of over 800 clozapine users diagnosed with a schizophrenia spectrum disorder. We meta-analyzed factors that were associated with response during clozapine treatment. Additionally, we conducted genetic association analyses to investigate the relations between side effects and symptom severity during clozapinetreatment. RESULTS: From our meta-analyses, we found that clozapine was more effective when used as a first- or second-line treatment. Furthermore, we found that younger age, less negative symptoms and the paranoid subtype of schizophreniawere associated with a better clozapine response. Several specific locations on genes (loci) were associated with clozapine-induced agranulocytosis and neutropenia, while polygenic risk scores were associated with symptom severity. CONCLUSION: We found that clozapine could be effective earlier in treatment and identified factors that could aid the prediction of< response to clozapine treatment in the future. These finding could contribute to the start of a personalized clozapine treatment.

[Genetic risk of mental illness: what do we know and how do we communicate this?] / Genetisch risico van psychiatrische ziekten: wat weten we en hoe communiceren we dat?

BACKGROUND: Insights from psychiatric genetics research and large international psychiatric genetics consortia are promising but still remain outside the realm of clinical practice.
AIM: To provide an overview of developments in the field of psychiatric genetics; and to offer guidance for health professionals how to assess and manage clinical implications of these developments.
METHOD: In this review, we address: recent developments in psychiatric genetics, with a focus on polygenic risk scores (PRS); ethical dilemmas associated with clinical application of PRS; and basic principles of genetic counseling for psychiatric disorders.
RESULTS: PRS are not yet ready for implementation in clinical practice because of limited predictive value and poor generalizability. In addition, it is still unclear how genetic risk and PRS can be communicated clearly to patients and families.
CONCLUSION: Advances in psychiatric genetics and increased availability of genetic risk scores may lead to questions from patients and families coping with psychiatric illness. These questions may be best addressed using psychiatric genetic counseling techniques. We recommend that psychiatrists have some basic knowledge of psychiatric genetics and know how to refer their patients to a clinical geneticist. Implementing a psychiatric genetics theme in training and education may be helpful.
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[Guidelines on genetic testing in psychiatry: an overview]. / Leidraad genetisch testen in de psychiatrie.

BACKGROUND: In recent years, technological advances have led to the identification of numerous genetic variations that are associated with psychiatric symptoms. Establishing a genetic cause may provide patients and family members with an explanation for the problems and in specific cases allows targeted treatment of psychiatric and somatic (co)morbidity. At present, patients with psychiatric disorders are rarely referred for genetic testing. AIM: To provide an overview of literature and (inter)national guidelines in the field of genetic testing for patients with psychiatric disorder, and to present guidance on indications for genetic testing in clinical practice. METHOD: A systematic search was conducted in PubMed and Embase focusing on articles with recommendations on genetic testing in psychiatric disorders. In addition, national and international guidelines on genetic testing in psychiatry were studied. The main findings were summarized in an infographic. RESULTS: Based on the current literature and (inter)national guidelines, patients with (comorbid) intellectual disability should always be referred to a clinical geneticist. Psychiatrists should consider genetic testing in patients with other psychiatric disorders if there are ‘red flags’ such as a positive family history, congenital abnormalities, developmental delay, dysmorphic features, movement disorders or cognitive decline. Psychiatrists may request genetic testing themselves or refer patients to clinical geneticists. CONCLUSION: Psychiatric disorders may be underpinned by a genetic anomaly, particularly in patients presenting with psychiatric as well as somatic symptomatology. Psychiatrists should recognize symptoms and warning signs indicative of an underlying genetic abnormality, and know when to refer their patients for genetic testing.

Genome-wide association analyses of symptom severity among clozapine-treated patients with schizophrenia spectrum disorders.

Clozapine is the most effective antipsychotic for patients with treatment-resistant schizophrenia. However, response is highly variable and possible genetic underpinnings of this variability remain unknown. Here, we performed polygenic risk score (PRS) analyses to estimate the amount of variance in symptom severity among clozapine-treated patients explained by PRSs (R2) and examined the association between symptom severity and genotype-predicted CYP1A2, CYP2D6, and CYP2C19 enzyme activity. Genome-wide association (GWA) analyses were performed to explore loci associated with symptom severity. A multicenter cohort of 804 patients (after quality control N = 684) with schizophrenia spectrum disorder treated with clozapine were cross-sectionally assessed using the Positive and Negative Syndrome Scale and/or the Clinical Global Impression-Severity (CGI-S) scale. GWA and PRS regression analyses were conducted. Genotype-predicted CYP1A2, CYP2D6, and CYP2C19 enzyme activities were calculated. Schizophrenia-PRS was most significantly and positively associated with low symptom severity (p = 1.03 × 10-3; R2 = 1.85). Cross-disorder-PRS was also positively associated with lower CGI-S score (p = 0.01; R2 = 0.81). Compared to the lowest tertile, patients in the highest schizophrenia-PRS tertile had 1.94 times (p = 6.84×10-4) increased probability of low symptom severity. Higher genotype-predicted CYP2C19 enzyme activity was independently associated with lower symptom severity (p = 8.44×10-3). While no locus surpassed the genome-wide significance threshold, rs1923778 within NFIB showed a suggestive association (p = 3.78×10-7) with symptom severity. We show that high schizophrenia-PRS and genotype-predicted CYP2C19 enzyme activity are independently associated with lower symptom severity among individuals treated with clozapine. Our findings open avenues for future pharmacogenomic projects investigating the potential of PRS and genotype-predicted CYP-activity in schizophrenia.

[Validation of the Dutch Glasgow Anti- psychotic Side-Effect Scale for Clozapine]. / Glasgow Antipsychotica Bijwerkingen Schaal voor Clozapine; validatie van de Nederlandstalige versie.

BACKGROUND: To monitor the unique side effect pattern of clozapine, the Glasgow Antipsychotic Side-effect Scale for Clozapine (GASS-C) was developed in English and validated. This questionnaire was previously translated to Dutch, and revised, but not yet validated. AIM: The current study concerns the validation of the second revision of the GASS-C-NL-R2 for the Dutch language. METHOD: Two Spearman correlation tests were conducted to compare GASS-C-NL-R2 with the Dutch version of the Liverpool University Neuroleptic Side-Effect Rating Scale (LUNSERS) at two time p´oints. There was one week between these two time points. The test-retest reliability was determined using a Spearman correlation test and Cronbach's alpha on the GASS-C-NL-R2 between the two time points. In addition, a factor analysis was performed. RESULTS: Spearman's correlation coefficient between the GASS-C-NL-R2 and the LUNSERS was 0.830 (p < 0.001, n = 72) at the first time point and 0.684 (p < 0.001, n = 50) at the second time point. GASS-C-NL-R2 also had a strong test-retest reliability: Spearman's correlation coefficient was 0.680 (p < 0.001; n = 46), and Cronbach's alpha was 0.847, n = 78. Factor analysis showed that all questions were relevant. CONCLUSION: The current study shows that GASS-C-NL-R2 is a valid and reliable questionnaire to monitor side effects related to clozapine with a relatively high prevalence. Future studies should focus on the practical utility of GASS-C-NL-R2 with a larger sample size.

[Complaints about dental treatment: solving 2 practice dilemmas]. / Klachten over behandelingen; de oplossing van 2 praktijksituaties met een dilemma.

As far as we know, very little has been published in dental literature on how patients' complaints about their dentist's treatment are assessed and what methods are used to try and resolve these complaints with the accused dentist. On the basis of 2 cases, a successful strategy of dental advisers is outlined. How they developed a strategy to resolve the complaint satisfactorily, drawing on knowledge of the use of conversation techniques, with the accused dentist is emphasised. Early on in the conversation, it is particularly important for advisers to understand and sense the often quite emotional state of mind of the dentist. Thereafter, an account of the facts can be formulated and a strategy can be developed for assessing and possibly resolving the patient's complaint.

Polygenic risk scores for genetic counseling in psychiatry: Lessons learned from other fields of medicine.

Polygenic risk scores (PRS) may aid in the identification of individuals at-risk for psychiatric disorders, treatment optimization, and increase in prognostic accuracy. PRS may also add significant value to genetic counseling. Thus far, integration of PRSs in genetic counseling sessions remains problematic because of uncertainties in risk prediction and other concerns. Here, we review the current utility of PRSs in the context of clinical psychiatry. By comprehensively appraising the literature in other fields of medicine including breast cancer, Alzheimer's Disease, and cardiovascular disease, we outline several lessons learned that could be applied to future studies and may thus benefit the incorporation of PRS in psychiatric genetic counseling. These include integrating PRS with environmental factors (e.g. lifestyle), setting up large-scale studies, and applying reproducible methods allowing for cross-validation between cohorts. We conclude that psychiatry may benefit from experiences in these fields. PRS may in future have a role in genetic counseling in clinical psychiatric practice, by advancing prevention strategies and treatment decision-making, thus promoting quality of life for (potentially) affected individuals.

Isolated nausea and vomiting as the cardinal presenting symptoms of clozapine-induced myocarditis: a case report.

BACKGROUND: Clozapine is an atypical antipsychotic proven to be superior in the treatment of treatment-resistant schizophrenia. Myocarditis is a rare, but well-known complication of treatment with clozapine. Only few cases have been reported in which nausea and vomiting were prominent symptoms. This is the first described report in which nausea and vomiting were the only presenting symptoms of clozapine-induced myocarditis. CASE PRESENTATION: We report a case of a 58-year-old woman, suffering from schizoaffective disorder, who is being treated with clozapine. Two weeks after initiation of clozapine, she developed nausea and vomiting, in absence of any other clinical symptoms. Laboratory examination and magnetic resonance imaging confirmed the diagnosis of clozapine-induced myocarditis. Clozapine was discontinued and the patient recovered fully. CONCLUSIONS: This case emphasizes the importance of recognizing myocarditis as a cause of isolated nausea and vomiting in patients treated with clozapine. Early recognition improves clinical outcome and reduces mortality.

Longitudinal associations of experiences of adversity and socioeconomic disadvantage during childhood with labour force participation and exit in later adulthood.

The Extending Working Lives (EWL) agenda seeks to sustain employment up to and beyond traditional retirement ages. This study examined the potential role of childhood factors in shaping labour force participation and exit among older adults, with a view to informing proactive interventions early in the life-course to enhance individuals' future capacity for extending their working lives. Childhood adversity and socioeconomic disadvantage have previously been linked to ill-health across the life-span and sickness benefit in early adulthood. This study builds upon previous research by examining associations between childhood adversity and self-reported labour force participation among older adults (aged 55). Data was from the National Child Development Study - a prospective cohort of all English, Scottish, & Welsh births in one week in 1958. There was evidence for associations between childhood adversity and increased risk of permanent sickness at 55 years - which were largely sustained after adjustment for educational disengagement and adulthood factors (mental/physical health, qualifications, socioeconomic disadvantage). Specifically, children who were abused or neglected were more likely to be permanently sick at 55 years. In addition, among males, those in care, those experiencing illness in the home, and those experiencing two or more childhood adversities were more likely to be permanently sick at 55 years. Childhood factors were also associated with part-time employment and retirement at 55 years. Severe childhood adversities may represent important distal predictors of labour force exit at 55 years, particularly via permanent sickness. Notably, some adversities show associations among males only, which may inform interventions designed to extend working lives.

Modeling non-inherited antibiotic resistance.

A mathematical model is presented for the increase and decrease of non-inherited antibiotic resistance levels in bacteria. The model is applied to experimental data on E. coli exposed to amoxicillin or tetracyclin in different concentrations. The parameters of the model are estimated using a Monte Carlo Markov Chain method. The model accurately describes build-up and decline of antibiotic resistance caused by physiological adaptations as long as no genetic changes have occurred. The main conclusion of the analysis is that short time periods are sufficient to re-obtain low MIC-values after long-lasting exposure to these antibiotics.

The effect of the breeding season, cryopreservation and physiological extender on selected sperm and semen parameters of four ferret species: implications for captive breeding in the endangered black-footed ferret.

In the present investigation, comparative baseline information on selected sperm characteristics of ejaculate spermatozoa of the domestic (Mustela putorius furo), fitch (Mustela sp.) and black-footed ferrets (Mustela nigripes) and the Siberian polecat (Mustela eversmanni) are presented. The main emphasis was to establish differences and similarities among these species in relation to semen and sperm quality during the breeding season, in cryopreservation success and in supporting sperm motility in different extenders or physiological media. The results confirm that most sperm morphology abnormalities were evident during the beginning of the breeding cycle in all four species. No significant interspecies differences were apparent in the sperm attributes examined, for all sampling months during the breeding season. Moreover, all species exhibited comparable patterns of reproductive seasonality. Cryopreservation suppressed sperm characteristics equally in all species studied. Ejaculate spermatozoa of closely related ferret species shared many similar motion characteristics using computer-aided sperm motility analysis. These results suggest that the basic sperm physiology of the ferret species under examination is very similar. Disparate to the interspecies comparisons, there were significant differences for most sperm motion parameters when spermatozoa of any of the ferrets were compared in different extenders. Assisted reproductive technologies developed for use in domestic ferret, fitch ferret or Siberian polecat may be successfully applied to captive breeding of the black-footed ferret using semen during any of the functional breeding months.

[Prospective comparison of the flow chart for laboratory investigations for anaemia from the Dutch College of General Practitioners' guideline 'Anaemia' with a self-developed, substantive and logistical alternative flow chart]. / Prospectieve vergelijking van het stroomschema voor laboratoriumonderzoek van anemie uit de NHG-standaard 'Anemie' met een eigen, inhoudelijk en logistiek alternatief stroomschema.

OBJECTIVE: To compare the flow diagram for the diagnosis of anaemia from the guideline 'Anaemia' from the Dutch College of General Practitioners (NHG) with a substantive and logistical alternative protocol. DESIGN: Prospective. METHOD: For evaluation of anaemia, 124 patients from primary care reported to the laboratories of the St. Elisabeth Hospital in Tilburg (n = 94) and the Scheper Hospital in Emmen (n = 30), the Netherlands. Two flow charts were used: the NHG's flow chart and a self-developed chart in which not mean corpuscular volume, but ferritin concentration occupies the central position. All the laboratory tests mentioned in both flow charts were carried out in every patient with, for practical reasons, the exception of Hgb electrophoresis and bone marrow investigations. General practitioners were approached and patient dossiers were consulted to obtain further clinical data. RESULTS: According to the NHG protocol, on the grounds of the laboratory investigations, 64 (52%) of patients could not be put in a specific category. The majority were patients with normocytary anaemia who did not fulfil the criteria for iron deficiency anaemia or the anaemia of chronic disease. According to the alternative chart, in 36 (29%) patients no diagnosis was made. These were patients in whom no abnormal laboratory findings were observed, other than low haemoglobin values. The majority of the patients had normocytary anaemia, in some cases this was interpreted as the anaemia of chronic disease, but more often the anaemia could not be assigned to a particular category. A large number ofpatients had a raised creatinine value. This value did not appear in the NHG protocol. In 15% of patients, more than one cause for anaemia was found. The NHG protocol did not enable these multiple diagnoses to be made. Accordingly, the NHG protocol was difficult to implement in the laboratory. CONCLUSION: Using the NHG flow diagram a large percentage of patients could not be assigned to a particular category. Using the alternative flow diagram, which procedure is easier to carry out in the laboratory, it was possible to make multiple diagnoses.

A newly developed tool for intra-tracheal temperature and humidity assessment in laryngectomized individuals: the Airway Climate Explorer (ACE).

The aim of this study is to develop a postlaryngectomy airway climate explorer (ACE) for assessment of intratracheal temperature and humidity and of influence of heat and moisture exchangers (HMEs). Engineering goals were within-device condensation prevention and fast response time characteristics. The ACE consists of a small diameter, heated air-sampling catheter connected to a heated sensor house, containing a humidity sensor. Air is sucked through the catheter by a controlled-flow pump. Validation was performed in a climate chamber using a calibrated reference sensor and in a two-flow system. Additionally, the analyser was tested in vivo. Over the clinically relevant range of humidity values (5-42 mg H2O/l air) the sensor output highly correlates with the reference sensor readings (R2 > 0.99). The 1-1/e response times are all <0.5 s. A first in vivo pilot measurement was successful. The newly developed, verified, fast-responding ACE is suitable for postlaryngectomy airway climate assessment.

[Diversity of complaints in manifesting carcinoma of the gallbladder]. / Diversiteit in klachten bij manifestatie van het galblaascarcinoom.

A man of 47 years with hypercholesterolaemia had no complaints but the family doctor suspected cholecystolithiasis because of abnormal results of the haematological study. Ultrasonography of the abdomen revealed a polyp in the gallbladder. The patient underwent laparoscopic cholecystectomy. Pathological examination revealed that the polyp was a carcinoma. No evidence for a recurrence was found during a return visit after 2 years. A woman of 74 years was admitted to the hospital due to persistent rectal bleeding. She had fever, loss of appetite, nausea and weight loss. A bleeding duodenal ulcer was identified during gastroduodenoscopy. Laparotomy was performed due to haemodynamic instability. During the operation an abnormal gallbladder was found with infiltration in and perforation of the duodenum. The gallbladder was resected and the perforation of the duodenum was sutured. Pathological examination revealed carcinoma of the gallbladder. A palliative policy was adhered to; the patient died 1 month later. Carcinoma ofthe gallbladder is an uncommon but highly fatal malignancy. Several risk factors have been identified and treatment is primarily surgical.

Ultrafast infrared spectroscopy reveals a key step for successful entry into the photocycle for photoactive yellow protein.

Photoactive proteins such as PYP (photoactive yellow protein) are generally accepted as model systems for studying protein signal state formation. PYP is a blue-light sensor from the bacterium Halorhodospira halophila. The formation of PYP's signaling state is initiated by trans-cis isomerization of the p-coumaric acid chromophore upon the absorption of light. The quantum yield of signaling state formation is approximately 0.3. Using femtosecond visible pump/mid-IR probe spectroscopy, we investigated the structure of the very short-lived ground state intermediate (GSI) that results from an unsuccessful attempt to enter the photocycle. This intermediate and the first stable GSI on pathway into the photocycle, I0, both have a mid-IR difference spectrum that is characteristic of a cis isomer, but only the I0 intermediate has a chromophore with a broken hydrogen bond with the backbone N atom of Cys-69. We suggest, therefore, that breaking this hydrogen bond is decisive for a successful entry into the photocycle. The chromophore also engages in a hydrogen-bonding network by means of its phenolate group with residues Tyr-42 and Glu-46. We have investigated the role of this hydrogen bond by exchanging the H bond-donating residue Glu-46 with the weaker H bond-donating glutamine (i.e., Gln-46). We have observed that this mutant exhibits virtually identical kinetics and product yields as WT PYP, even though during the I0-to-I1 transition, on the 800-ps time scale, the hydrogen bond of the chromophore with Gln-46 is broken, whereas this hydrogen bond remains intact with Glu-46.

How light-induced charge transfer accelerates the receptor-state recovery of photoactive yellow protein from its signaling state.

Stark (electroabsorption) spectra of the M100A mutant of photoactive yellow protein reveal that the neutral, cis cofactor of the pB intermediate undergoes a strikingly large change in the static dipole moment (|Deltamu| = 19 Debye) on photon absorption. The formation of this charge-separated species, in the excited state, precedes the cis --> trans isomerization of the pB cofactor and the regeneration of pG. The large |Deltamu|, reminiscent of that produced on the excitation of pG, we propose, induces twisting of the cis cofactor as a result of translocation of negative charge, from the hydroxyl oxygen, O1, toward the C7-C8 double bond. The biological significance of this photoinduced charge transfer reaction underlies the significantly faster regeneration of pG from pB in vitro, on the absorption of blue light.

From primary photochemistry to biological function in the blue-light photoreceptors PYP and AppA.

To properly respond to changes in fluency conditions, Nature has developed a variety of photosensors that modulate gene expression, enzyme activity and/or motility. Dedicated types have evolved, which can be classified in six families: rhodopsins, phytochromes, xanthopsins, cryptochromes, phototropins and BLUF-proteins. The photochemistry of the first three families is based on cis/trans isomerization of an ethylene bond. Surprisingly, the latter three all use flavin as their chromophore, but each with very different photochemistry. In this contribution we will discuss the molecular basis of signal generation in a xanthopsin (Photoactive Yellow Protein (PYP) from Halorhodospira halophila), a photoreceptor for negative phototaxis, and in a BLUF protein (AppA from Rhodobacter sphaeroides), a transcriptional anti-repressor. PYP is activated through trans/cis isomerization of the 7,8-vinyl bond of its 4-hydroxycinnamic acid chromophore. This initiates a photocycle with multiple intermediates, like pB, which is formed after intramolecular proton transfer. The negative charge thus formed in the interior of the protein triggers formation of a partially unfolded signaling state. For AppA much less is known about the underlying photochemistry. Available evidence suggests that it is based on a light-induced change in the hydrogen-bonding of its flavin chromophore and/or a change in hydrophobic stacking between the flavin and/or nearby aromatic amino acids like Y 21. A signaling state is formed within microseconds, which recovers with a rate of approximately 10(-3) s(-1). The change in conformation between receptor- and signaling-state in AppA, however, appear to be minute as compared to those in PYP. Here we review the underlying chemistry in the various steps of the photocycle of these two photoreceptor proteins and provide new data on their mechanism and function.

[Lifestyle of Dutch people aged 55-64 years less healthy in 2002/'03 than in 1992/'93]. / Leefstijl van 55-64-jarige Nederlanders in 2002/'03 minder gezond dan in 1992/'93.

OBJECTIVE: To describe the lifestyle of men and women aged 55-64 years in The Netherlands in 2002/'03 and compare it with the lifestyle of people of the same age in 1992/'93. DESIGN: Descriptive. METHOD: Data were used from the Longitudinal Aging Study Amsterdam. The study comprised two randomly selected samples from local municipal registers in 1992/'93 (n = 966) and 2002/'03 (n = 1002), stratified according to sex, age and expected 5-year survival. Participants were from 11 municipalities in the west, northeast and south of The Netherlands. Data were collected from interviews, measurements and a written questionnaire. The response was 62% in 1992/'93 and 57% in 2002/'03. RESULTS: In 1992/'93, 9.5% of the men and 20.5% of the women were obese. Ten years later these percentages were 18.4 and 27.5. The percentage of current smokers was stable over time and included one-third of men and one-quarter of women. More people used alcohol in 2002/'03; excessive alcohol use was found in 15.7% of the men (11.7% in 1992/'93) and 19.5% of the women (11.1% in 1992/'93). The energy expended through walking, bicycling, household activities and sports was one-fifth less in 2002/'03. CONCLUSION: The lifestyle of people aged 55-64 years in The Netherlands was less healthy in 2002/'03 than in 1992/'93. Because positive changes in lifestyle can reduce the risk of chronic diseases, functional limitations and early death, more attention to healthy living is necessary in this age group.

Stark spectroscopy on photoactive yellow protein, E46Q, and a nonisomerizing derivative, probes photo-induced charge motion.

The change in the electrostatic properties on excitation of the cofactor of wild-type photoactive yellow protein (WT-PYP) have been directly determined using Stark-effect spectroscopy. We find that, instantaneously on photon absorption, there is a large change in the permanent dipole moment, /Delta(-->)mu/, (26 Debye) and in the polarizability, (-)Deltaalpha, (1000 A(3)). We expect such a large degree of charge motion to have a significant impact on the photocycle that is associated with the important blue-light negative phototactic response of Halorhodospira halophila. Furthermore, changing E46 to Q in WT-PYP does not significantly alter its electrostatic properties, whereas, altering the chromophore to prevent it from undergoing trans-cis isomerization results in a significant diminution of /Delta(-->)mu/ and (-)Deltaalpha. We propose that the enormous charge motion that occurs on excitation of 4-hydroxycinnamyl thioester, the chromophore in WT-PYP, plays a crucial role in initiating the photocycle by translocation of the negative charge, localized on the phenolate oxygen in the ground state, across the chromophore. We hypothesize that this charge motion would consequently increase the flexibility of the thioester tail thereby decreasing the activation barrier for the rotation of this moiety in the excited state.

Nitric oxide inhibition enhances platelet aggregation in experimental anti-Thy-1 nephritis.

In the present paper we studied the role of nitric oxide radicals (NO) on platelet aggregation, fibrinogen deposition, superoxide formation, peroxynitrite formation, hemodynamics, and leukocyte migration in the Thy-1 model of glomerulonephritis. To first study the baseline kinetics of these parameters, groups of anti-Thy-1-treated rats were sacrificed at 1 h, 4 h, 24 h, 3 days, 7 days, and 14 days and compared to controls. Urinary protein excretion was significantly elevated in Thy-1 nephritis at 3 and 7 days. Glomerular macrophages, PMNs, and superoxide anion-positive cells were significantly increased in Thy-1 nephritis. Nitrotyrosine immunoreactivity was absent during the entire study period. Glomerular platelet aggregation was significantly increased in anti-Thy-1 injected rats at 1 h, 4 h, 24 h, and 3 days. Glomerular fibrinogen deposition was significantly elevated at all time points. To elucidate the role of NO in this process, additional groups of anti-Thy-1-injected rats were treated with the NOS inhibitor l-NAME and studied at 24 h. Urinary protein excretion was significantly higher in l-NAME treated Thy-1 rats compared to nontreated Thy-1 rats. Plasma and urine nitrite/nitrate levels were significantly lower in l-NAME-treated Thy-1 rats compared to nontreated Thy-1 rats. Compared to nontreated Thy-1 rats, there were no differences in intraglomerular leukocyte accumulation after treatment with l-NAME. In contrast, we observed a marked increase in platelet aggregation following l-NAME treatment. From these data we conclude that the inflammatory infiltrate in Thy-1 nephritis develops independent of NO radical production, whereas NO radicals prevent the accumulation of platelet aggregates.