Affective illness in family members and matched controls

As part of the US National Institute of Mental Health Collaborative Program on the Psychobiology of Depression study, a subset of 460 randomly chosen relatives of affectively ill probands were compared to a control group matched by the acquaintanceship method. The rate of major affective disorder in relatives was found to be 36%; the rate among controls was 28%. Relatives were also found to have significantly higher rates of bipolar II disorder, any Research Diagnostic Criteria (RDC) affective disorder and any RDC mental disorder. All of these rates were found to be significantly higher when female relatives were compared with their acquaintances, but only the rate of any RDC mental disorder was higher when this comparison was made in men. The acquaintanceship method enabled the selection of a control group that closely resembled the relatives, probably to the extent of "overmatching". When the match was evaluated to determine whether relatives tended to select comparably ill (or well) acquaintances, this was found to be the case only for alcoholic and never mentally ill relatives.

Squamous cell carcinoma of the prostate: a transformation from adenocarcinoma after the use of a luteinizing hormone-releasing hormone agonist and flutamide

We report a primary squamous cell carcinoma of the prostate that developed in a 57-year-old man, 3 years after treatment with leuprolide and flutamide for Stage D1 adenocarcinoma of the prostate. This is the first case that describes this transformation from adenocarcinoma to squamous cell carcinoma following the use of luteinizing hormone agonists.

White cell-reduced platelet concentrates prepared by in-line filtration of platelet-rich plasma

BACKGROUND

The importance of white cell (WBC) reduction in platelet concentrates (PCs) for component quality is undetermined.

STUDY DESIGN AND METHODS

Eleven paired components, each derived from one of two whole-blood units given by a single donor on the same day, were studied. One PC was WBC reduced by filtration with an in-line, integral, prototype filter, and the other was produced from unfiltered platelet-rich plasma (PRP) by a standard method. In vitro tests performed on Day 1 and Day 5 were blood gases, plasma lactate, glucose, platelet ATP, mean platelet volume, morphology score, hypotonic stress ratio, extent of shape change in response to ADP, and beta-thromboglobulin. After 5 days of storage, each component pair was labeled with 51Cr or 111In and transfused for the estimation of percent recovery and survival.

RESULTS

PCs using the in-line, prototypic filter had a platelet loss of approximately 15 percent and a variable 1 to 3 log10 reduction (average, 95%) in WBC content. The variation in filter WBC removal was related to PRP WBC content and indicated that the filter did not have the capacity for a 3 to 4 log10 removal when PRP WBC content exceeded 1 x 10(8). The in vitro and in vivo measures of platelet quality showed no meaningful differences between filtered and unfiltered PCs by paired t test. The mean differences in posttransfusion percent recoveries and survivals were 0.9 +/- 2.9 percent and 4 +/- 13 hours, respectively. Additional studies were performed using a larger filter with improved capacity. Those studies (n = 18) showed a significant improvement in filtration time and platelet yield and a consistent 3 to 4 log10 reduction in WBCs. Filtration time was 6.6 +/- 2.7 minutes, total PC WBCs were 9.6 +/- 4.6 x 10(4), and total PC platelets were 7.8 +/- 1.8 x 10(10) (mean +/- SD).

CONCLUSION

Prestorage filtration of PRP and the preparation of filtered platelets do not result in any significant beneficial or adverse effect on subsequent platelet quality. With the large-capacity filter, consistent WBC reduction and good platelet yields are achieved.

The effects of melatonin on isolation distress in chickens

Melatonin (0.1-1.0 mg/kg) reduced isolation-induced distress vocalizations (DVs) in young domestic chickens in a dose-dependent manner. This effect was unaffected by the administration of d-amphetamine (1.0 mg/kg) suggesting that melatonin's effects were not merely due to fatigue. The melatonin reduction in DVs was not naloxone reversible, indicating an action independent of the endogenous opioid system. However, chronic pretreatment with naltrexone facilitated the melatonin effect, suggesting a complex relationship between melatonin and the endogenous opioids in regulating distress vocalizations. Chickens exhibited a marked reduction in DVs when isolation chambers were darkened, suggesting endogenous, as well as exogenous, melatonin mediation of isolation distress; however; pinealectomy only partially reversed the darkness effect. Pinealectomized animals, like control animals, exhibited a reduction in DVs following melatonin treatment; however, the melatonin effect was shorter lasting. The implications that these results may have for socialization and emotional distress are discussed.

Brain opioids and mother-infant social motivation

Brain opioids were the first neurochemical system to be implicated in the elaboration of social-bonding processes. Although a variety of neurochemical systems help elaborate social rewards and specific social behaviors, the role of opioids in the control of maternal behavior remains controversial. Although a great deal of data indicate that intermediate doses of morphine can reduce maternal behavior, the evidence, taken together, suggests that endogenous opioids promote the regulatory control of maternal behavior, probably by providing feedback concerning the satisfaction that can be had from indulging in various maternal behaviors. Thus opioid blockade with naltrexone can reduce maternal competence in animals, while at the same time increasing maternal motivation. Opiate blockade likewise appears to increase the social motivation of rat pups, but reduces the reinforcing quality of interaction with the mother, suggesting that opioids provide feedback concerning the pleasurable qualities of social interaction in both mothers and infants. The clinical implications of this knowledge are not straightforward, but they generally suggest that clinically deficient social bonding might be capable of being strengthened via manipulation of brain opioid systems.

Effects of 3-5 log10 pre-storage leucocyte depletion on red cell storage and metabolism

A new, in-line high-efficiency 3-5 log10 leucodepletion filter system (Leukotrap RC system) was used to investigate the effect of pre-storage white cell removal on the quality of AS-3 red cell concentrates stored for 42 d at 4 degrees C. Median residual white cell content was 4 x 10(5) when filtration was performed at 22 degrees C within 8 h of phlebotomy (n = 20) and 3.2 x 10(4) when filtration was performed at 4 degrees C 12-24 h after phlebotomy (n = 24). None exceeded 1 x 10(6) WBC per red cell product. Filtration was rapid (median 28 min), and red cell loss averaged (mean +/- 1 SD) 6.4 +/- 0.7%. In a paired study design, post-transfusion recoveries of 42 d stored red cells in the filtered units averaged 84 +/- 6% v 82 +/- 8% for unfiltered units (P < 0.05) and post-storage haemolysis. ATP, osmotic fragility, K+ and pH were significantly (P < 0.05) better in the filtered units. Reduced glycolytic activity was also observed in the filtered units, and there was a correlation between osmotic fragility, glucose consumption, and lactate produced in standard units that was not present in leucodepleted units. In conclusion, this study suggests that leucodepletion of AS-3 red cell concentrates prior to storage results in better maintenance of the integrity of the red cell membrane with reduced glycolytic activity. There was a modest improvement in post-infusion viability sufficient to offset the filtration-induced loss and to result in an equivalent red cell product.

Children who have a parent with cancer: a pilot study

This British pilot study was undertaken to determine whether the children of cancer patients experience problems and anxieties related to the parent's diagnosis and treatment. The data were collected by means of semistructured interviews with 24 adolescent children (16 sons, eight daughters) whose parents' cancers had been diagnosed between two and six years previously (mean four years). Self-report questionnaires to assess adolescent anxiety were also completed at the interviews. The results show that some of the children experienced problems and anxieties related to their parents' cancers that affected their school lives, sports and leisure activities, family lives, and relationships. Factors that were significantly associated with high anxiety scores were: inability to discuss the parent's illness with parents; having to spend less time with friends; having to spend less time on sport and leisure activities; deterioration in schoolwork; and continuing anxiety over the parent's illness.

Cardioteratogenic dose of ethanol in the chick embryo results in albumin ethanol concentrations comparable to human blood alcohol levels

Three-day-old chick embryos (Hamburger-Hamilton stages 18-19) were exposed to a dose of ethyl alcohol (0.32 ml of 50% ethanol) that causes cardiac malformations in 96.6% of the animals. Ethanol was administered into the air sac after 72-80 h of incubation. Samples of albumin at the opposite pole of the egg were drawn 0-50 h after treatment and quantitated for ethanol concentration with capillary gas-liquid chromatography. Ethanol concentrations in the albumin increased significantly (P < 0.05) at 2, 5 and 15 h after injection of ethanol, reached a maximum mean ethanol concentration at 20 h (217.3 +/- 23.5 mg dl-1), decreased significantly at 30 h to 175.4 +/- 27.5 mg dl-1, then increased again and stabilized at 40-50 h. Individual sample concentrations ranged from 0 mg dl-1 (at 0.5-2 h) to 286.5 mg dl-1 at 40 h. Ethanol concentrations in the albumin were comparable to human blood alcohol levels during intoxication (> 150 mg dl-1). Our results suggest that a potent cardioteratogenic dose of ethanol in the chick embryo is reasonable in terms of potential human embryo exposure.

Visual attention in obsessive-compulsive disorder

Performance on neuropsychological tasks was compared in 15 subjects with obsessive-compulsive disorder (OCD) and 15 age- and sex-matched psychiatrically screened control subjects. The tasks chosen are known from studies in other patient groups to demonstrate lateralized abnormalities of visual and limited capacity attentional impairment. The Posner task performance of the OCD group demonstrated decreased inhibition of return for left visual field targets and no inhibition of return for right visual field targets. The OCD group's spatial-linguistic conflict task responses were significantly slowed in the conflict condition, as predicted. The results are discussed in relation to the phenomenology of OCD and prior neuropsychological evaluations.

Laboratory investigation of PRRS virus infection in three swine herds

Late in 1991, an enveloped RNA virus (now called porcine reproductive and respiratory syndrome [PRRS] virus) was identified as the etiologic agent for mystery swine disease. In 1992, laboratory procedures for the diagnosis of this disease evolved rapidly, and veterinary diagnosticians started applying these tests to field cases. This report is written from the perspective of veterinary laboratory diagnosticians and utilizes 3 case studies to define the advantages and disadvantages of the various available diagnostic laboratory PRRS test procedures in different clinical situations. The diagnostic procedures currently used in our laboratory for investigating PRRS are pathologic examination, serologic testing, fluorescent antibody (FA) testing, and virus isolation. Interstitial pneumonia, characterized by mononuclear cell infiltration of alveolar walls with normal airway epithelium, is a hallmark lesion for the disease, especially in neonatal pigs with respiratory distress. Interstitial pneumonia is not a specific lesion and must be coupled with other tests to verify PRRS virus infection. Demonstration of seroconversion is helpful, especially in sows that have experienced reproductive failure. The indirect FA test detects antibody sooner than the serum neutralization test and will likely become the serologic test of choice. The direct FA test on fresh tissue utilizes monoclonal antibody and is useful for investigating PRRS virus-associated pneumonia. Virus isolation utilizing swine alveolar macrophages has also been a useful diagnostic procedure. All of the above tests have been universally unrewarding when applied to aborted, mummified, or stillborn piglets.

Association between major depressive disorder and physical illness

The association between major depressive disorder (MDD) and self-reported histories of specific physical illnesses was investigated in 320 controls and 1968 first-degree relatives and 254 spouses of probands in the NIMH Collaborative Depression study. The Schedule for Affective Disorders and Schizophrenia-Lifetime Version was used to assign Research Diagnostic Criteria (RDC) diagnoses and a structured self-report instrument was used to assess lifetime medical history. Lifetime MDD was diagnosed in 914 subjects, 402 of whom had been hospitalized or received somatic treatment ('treated' MDD). Strong associations were observed between MDD (either treated or untreated) and both frequent/severe headaches and migraine headaches. There was a marked gender effect such that the relative odds for a woman with treated MDD to report migraine were over 5:1. Other associations were found between MDD and skin infections, respiratory illness, ulcer, hypotension, and diabetes. This is the largest non-patient sample using standardized assessment of mental disorders by direct interview in which associations between specific physical illnesses and MDD have been demonstrated. Implications for clinical practice and neurobiological research in depression are discussed.

Genotoxic effects of subacute treatments with wood dust extracts on the nasal epithelium of rats: assessment by the micronucleus and 32P-postlabelling

Human exposure to wood dust has been epidemiologically linked to a number of enhanced incidences of various neoplasias, including those of the nose. Among different suspected woods, long-term exposure to the dust of beech (Fagus silvatica) is strongly associated with development of these tumors. Experimentally, it has been shown that a simple alcoholic extract of beech wood dust is mutagenic toward some bacteria and tumorigenic on mouse skin. For the present study, different groups of male Wistar rats were treated with aqueous, ethanol, or methanol extract of untreated beech wood dust via nasal drip at three concentrations for 48 h. Animals were killed 24 h after the last treatment and the nasal tissues were isolated to be examined for possible induction of micronuclei and DNA adducts. A clear dose-dependent increase in the number of micronuclei (P < 0.01) was observed after treatment of rats with each alcoholic extract of wood dust. In contrast, no DNA adducts could be detected with these extracts using the 32P-postlabelling technique. No increased number of micronucleated cells was found with solvents alone or with aqueous extract of dust. These data might support the early hypothesis that wood dust per se contains some in vivo genotoxic and thus possibly carcinogenic components extractable by an alcohol.

A vaccinia-vectored rabies vaccine field trial: ante- and post-mortem biomarkers

During the field safety evaluation of a vaccinia-rabies glycoprotein recombinant virus vaccine for wildlife, two biomarkers were used to identify potential contact with vaccine-laden baits. Tetracycline, a commonly used and reliable calciphilic tissue marker, was included in a fish-meal polymer bait matrix and was evaluated from post-mortem bone samples. Additionally, an ante-mortem marker was needed to identify, for prospective study, raccoons which had contacted baits and thus, potentially, vaccine. Sulfadimethoxine (SDM) was included in an attractant slurry surrounding the bait, as a novel short-term seromarker. Preliminary laboratory studies in raccoons demonstrated SDM residues for up to one week following ingestion of a single 250 mg dose. During the first six days after bait distribution, 49 individual raccoons were live-trapped in the vaccination area. SDM was detectable in 38 of 49 (77.5%) serum samples. Similarly, 47 of 56 (83.9%) bone samples from raccoons collected in the vaccination area throughout the twelve-month study were tetracycline-positive. Conversely, none of the serum samples (n = 12) from the first six days of the trial nor any of the bone samples (n = 34) from raccoons in the surveillance area were biomarker-positive.

Shoulder pain in wheelchair athletes. The role of muscle imbalance

Shoulder rotator cuff impingement syndrome is a common and disabling problem for the wheelchair athlete. In this study we investigated the role of shoulder strength imbalance as a factor for the development of this syndrome. Nineteen paraplegic male athletes underwent clinical and isokinetic examination of both shoulders with peak torque values measured in abduction, adduction, and internal and external rotation. Twenty athletic, able-bodied men without shoulder problems were tested as controls. Ten (26%) of the paraplegic athletes had rotator cuff impingement syndrome. The results of the isokinetic testing demonstrated that 1) the paraplegics' shoulders were stronger than the controls in all directions (P < 0.05); 2) the strength ratio of abduction: adduction was higher for paraplegic athletes (P < 0.05); 3) paraplegics' shoulders with rotator cuff impingement syndrome were weaker in adduction and external and internal rotation than the paraplegic athletes without impingement syndrome (P < 0.05); and 4) paraplegics' shoulders with rotator cuff impingement syndrome had higher abduction:adduction and abduction:internal rotation strength ratios than the shoulders of paraplegics without impingement syndrome (P < 0.05). We concluded that shoulder muscle imbalance, with comparative weakness of the humeral head depressors (rotators and adductors), may be a factor in the development and perpetuation of rotator cuff impingement syndrome in wheelchair athletes.

Randomised comparison of routine versus highly selective use of Doppler ultrasound in low risk pregnancies

OBJECTIVE

To help answer the question: should Doppler ultrasound of the umbilical circulation be made available to all pregnant women as part of their routine antenatal care?

DESIGN

A randomised trial.

SETTING

St James's University Hospital, Leeds.

SUBJECTS

2025 low risk primigravid women.

MAIN OUTCOME MEASURES

Obstetric intervention rates and short term neonatal morbidity.

RESULTS

The incidence of abnormal Doppler was low (1.7%) with complete absence of end diastolic flow in only 0.3% of cases. No significant differences could be demonstrated between control and study women in any of the outcomes measured.

CONCLUSION

This study did not demonstrate any benefit or harm from Doppler ultrasound as a routine screening test for all low risk women, whereas our previous studies have suggested that it is useful in high risk pregnancies. Any marginal returns on extending access to Doppler ultrasound from high risk to all women must be small. Since this test has excellent performance characteristics (sensitivity and specificity) for the prediction of fetal hypoxia and acidosis our results call into question the cost to benefit ratio of all tests designed to predict these outcomes in low risk women.

Lateralized attentional abnormality in schizophrenia is correlated with severity of symptoms

Numerous studies have demonstrated a lateralized impairment of attention in schizophrenia. In this study, attention in schizophrenia is investigated with a task that involves centering a rod while blindfolded. Symptoms were rated on the Brief Psychiatric Rating Scale (BPRS) for each of the 20 schizophrenic subjects. The more symptomatic patients demonstrated a right-sided hemineglect compared to the less symptomatic patients (p = 0.013). Furthermore, the difference between more and less symptomatic patients was even more distinct when they were categorized by the BPRS schizophrenia subscale alone (p = 0.0025). These findings support the hypothesis that the pathophysiology of schizophrenia involves a lateralized defect in the control of attention, and that this defect is associated with the severity of symptoms. This raises the possibility that effects of neuroleptic medication may be asymmetric, which could account for some of the inconsistencies in studies of hemispheric dysfunction in schizophrenia.

Informed decision making in persons acquitted not guilty by reason of insanity

Deciding to raise an insanity defense carries serious consequences. This is especially true for persons charged with minor offenses, for whom an acquittal not guilty by reason of insanity (NGRI) might lead to a longer period of incarceration than would conviction. Before raising an insanity defense, a defendant should be provided with information necessary to make an informed decision and should be competent to understand the consequences of the verdict. This study attempted, through retrospective review and concurrent evaluation, to determine the degree to which trial courts in Virginia attended to these important aspects of informed decision making before finding defendants charged with misdemeanors NGRI. The study also attempted to assess the degree to which defendants were competent and informed at the time of adjudication. In most instances, trial courts did not consider defendants' competence to make decisions regarding the insanity defense and did not consider whether defendants were informed about the consequences of a successful insanity defense at the time of adjudication. The average length of stay for these patients was (at least) 21 months; most would have been released earlier had they been committed civilly rather than committed as a result of insanity pleas. We stress the need to educate judges, attorneys and forensic evaluators to the importance of considering defendants competence to plead insanity and of providing information about the consequences of a successful plea. We also propose that laws be changed to recognize the importance of these elements in the decision making process regarding pleas of insanity.

The use of baseline investigations in patients admitted from an accident and emergency department

We studied the use of four investigations on patients admitted from our Accident and Emergency Department: full blood count, urea and electrolytes, chest x-ray and electrocardiogram. We found 1) that these investigations were performed on a high proportion of patients admitted 2) that a high percentage of these investigations yielded normal results. We suggest that a greater emphasis should be placed on clinical assessment, rather than the 'routine' use of investigations.

Benefits and obstacles of health status assessment in ambulatory settings. The clinician's point of view. The Dartmouth Primary Care COOP Project

In the past decade physicians have identified the need to expand patient assessment to include global function and quality of life. During the same period, the busy clinic has evolved into the location where this assessment seems most appropriate. Integrating functional health assessment into a busy clinical practice is difficult because the necessary steps require time, thought, recording, and follow-up. Attention to the office ecosystem is very important before any patient care management method is introduced. The clinician must transform the results of health status screening into a specific functional diagnosis. The clinician has to understand the sensitivity, specificity, and predictive value of the measure for a preliminary diagnosis to be made. Often, additional measurements must be taken to establish a specific diagnosis. These steps encompass assessment linkage. Once the specific cause for the dysfunction is recognized, the clinician then has to determine the need for special resources. This is called the resource linkage. By following the steps outlined in this paper, the clinician should be able to overcome many obstacles for functional health status assessment in busy ambulatory settings.

The short-term effect of patient health status assessment in a health maintenance organization

This study was designed to test the short-term effects of health assessment on the process of care and patient satisfaction. The 29 Chart physicians used the Dartmouth COOP Charts to measure their adult patients' health status during a single clinical encounter; the 27 control clinicians used no measure of health status. We compared the change between baseline and post-intervention information for a sample of all study clinicians' patients. Most of the patients were female (67%), well educated (70% had at least a college education) and young (approximately 90% were aged 59 years or younger). We found that the ordering of tests and procedures for women was increased by exposure to the COOP Charts (52% vs. 35%; p < 0.01); the effect in men was not as significant (37% vs. 23%: p = 0.06). Although women reported no change in satisfaction with care, men claimed that the clinician helped in the management of pain (p = 0.02). We conclude that the use of health status measures during a single clinical encounter in an HMO changes clinician test ordering behaviour and may improve the help male patients receive for pain conditions. The long-term impact of these management changes is not known.

Characterization of swine infertility and respiratory syndrome (SIRS) virus (isolate ATCC VR-2332)

The characterization of an isolate of swine infertility and respiratory syndrome (SIRS) virus (ATCC VR-2332) is reported. A commercial cell line (CL2621) was used for the propagation of the virus for all assays. Laboratory studies indicate that this isolate is a fastidious, nonhemagglutinating, enveloped RNA virus. Cesium chloride-purified virions visualized by electron microscopy were spherical particles with an average diameter of 62 nm (range: 48-83 nm) and a 25-30 nm core surrounded by an envelope. Virus replication was restricted to the cytoplasm, as demonstrated by immunofluorescence. The virus did not react serologically with antisera to several common porcine viruses or with antisera to known viruses in the alphavirus, rubivirus, pestivirus, and ungrouped lactic dehydrogenase virus genera of the Togaviridae. However, convalescent sow sera and rabbit hyperimmune sera neutralized the SIRS virus at titers of 1:256 and 1:512, respectively. The virus was stable at 4 and -70 C, but was labile at 37 and 56 C. The properties of this isolate of SIRS virus resemble those of the family Togaviridae but do not match the described genera.

Pathologic hair-pulling: a review of the literature and case reports

Pathologic hair-pulling (trichotillomania) has been described in the dermatologic and psychiatric literature for the last century, but has become the focus of increased attention in the last few years. Once thought to be either a wholly benign condition or a symptom of obsessive-compulsive disorder, more recently hair-pulling has been noted in the context of numerous types of psychopathology, and has been reported to respond to several different types of intervention, both psychological and somatic. Estimates of its prevalence have varied widely. Because of the disparate conclusions of the literature on this condition, a more careful assessment of diagnostic validity is recommended.

Paired comparison of platelet concentrates prepared from platelet-rich plasma and buffy coats using a new technique with 111In and 51Cr

Two techniques for the preparation of platelet concentrate (PC), the standard platelet-rich plasma (PRP) and buffy coat (BC) methods, were compared in nine paired studies with regard to platelet harvest, white cell (WBC) contamination, and PC quality after 5 days of 22 degrees C storage. Platelet harvest using the BC method averaged approximately 56 percent of the whole blood level (6.2 x 10(10)/concentrate), which was less than the 76 percent achieved with the PRP-PC method (8.7 x 10(10)/concentrate). An additional 5 units collected into an experimental siphon bag for BC-PC processing showed improved platelet harvest (6.7 x 10(10)/concentrate, or approx. 70% of whole blood). WBCs remaining in the BC-PC averaged 0.19 x 10(8) per unit compared to 3.6 x 10(8) per unit for PRP-PC. Buffy coat processing produced red cell (RBC) units with 50 percent of the WBC contamination of conventionally prepared units (9.8 +/- 6.2 x 10(8)/unit vs. 18.9 +/- 7.1 x 10(8)/unit). The siphon bag further reduced WBC levels in the AS-3 RBC units (6.4 +/- 3.7 x 10(8)/unit). In vitro studies performed on Days 1 and 5 after collection showed no significant differences in platelet metabolic and biologic function or cell integrity. Beta-thromboglobulin and surface glycoprotein levels, indicators of platelet activation and membrane alteration, respectively, did not differ significantly in the PRP-PC and BC-PC; nor was lactate production higher in PRP-PC, despite the substantially higher WBC counts. Autologous in vivo platelet viability determinations were performed by using concurrent transfusion of 111In-labeled freshly drawn platelets and 51Cr-labeled stored platelets.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of mercapturic acid excretions in exposure control to toxicants

Toxicants can be converted in vivo by a variety of biotransformation reactions into substances that are more, equally, or less noxious than the parent compound. Although conjugation with glutathione is a process that usually results in less harmful products, these products might subsequently form new metabolites that exert more toxicity than the parent compound. These conjugation reactions are catalyzed by several classes of glutathione-S-transferase isoenzymes and thus result in the urinary or biliary excretion of N-acetyl-L-cysteine-S-conjugates (mercapturic acids). Inasmuch as GSH-S-transferase activity varies among different tissues, urinary excretion of mercapturic acids might reflect tissue-specific toxicity. Urinary mercapturic acids are biomarkers of internal and, in some cases, effective dose. The utility of these markers is, however, limited to times shortly after exposure. Studies on possible human deficiencies in some GSH-S-transferases might help us better understand interindividual variations in susceptibility to different toxicants and thus the differences in the pathway of mercapturic acid excretion pattern.