Differential antioxidant enzyme activities and glutathione content between rat and rabbit conceptuses

Redox status regulates numerous cellular processes like transcription factor activation and binding, protein folding, and calcium sequestration. Because the most abundant reducing equivalent in the cell is glutathione (GSH), it could play a role for teratogens that cause oxidative stress and disrupt pathways involved in differentiation and proliferation. Investigation of the redox status of two species that have demonstrated differential sensitivity to teratogens represents a novel approach for determining the role of redox alteration in teratogenesis. Furthermore, examining specific regions of the embryo may also help to explain why certain tissues are uniquely sensitive, while others are resistant to oxidative insult. In the presented study, New Zealand White rabbit (GD 12) and Sprague Dawley rat embryos (GD 13) were removed from the uterus on days of similar development. Each embryo was dissected into three portions-the limbs, the head, and the trunk. Samples were placed in the appropriate buffers for the measurement of both direct and indirect redox status contributors-GSH, cysteine, thioredoxin, glutathione disulfide, protein-glutathione mixed disulfides, superoxide dismutase, glutathione peroxidase, and glutathione disulfide reductase. Species comparison of whole embryos indicated that the rabbit embryo possesses a higher redox potential (more oxidative) than the rat embryo. Findings, in general, show that the rabbit may be more sensitive to redox-altering teratogens because it is inherently more pro-oxidizing and may be more easily perturbed resulting in misregulation of cellular processes. Differences were most apparent in the limb as compared to the embryonic head and trunk, where the rabbit limb has a significantly more pro-oxidizing redox environment than the rat limb. Species comparisons like these may help in the understanding of how redox shifts affect cellular processes and would contribute to regulation of biochemical and molecular events that may be associated with mechanisms of teratogenesis. These may contribute to a more complete rationale for choosing a species for study and provide a better correlation with human developmental toxicants.

Cutaneous neosporosis in two adult dogs on chronic immunosuppressive therapy

Antemortem diagnosis of generalized ulcerative and pyogranulomatous dermatitis with numerous intralesional tachyzoites was made from skin biopsy specimens from 2 adult dogs on chronic immunosuppressive therapy. A 9-year-old Italian Greyhound was on long-term corticosteroid therapy for the treatment of a lupus-like systemic autoimmune disorder, and a 7-year-old Labrador Retriever had received several months of chemotherapy for lymphosarcoma. The tachyzoites were identified as Neospora caninum by immunoperoxidase immunohistochemistry. Both dogs were treated with clindamycin. Lesions in the Greyhound resolved; however, the Labrador Retriever was euthanized because of evidence of neuromuscular disease, despite improvement of the skin lesions. These 2 cases indicate that cutaneous neosporosis can occur in adult dogs on chronic immunosuppressive therapy. The disease may result from reactivation of a congenital infection and/or a recently acquired primary infection.

Dose-escalation, phase I/II study of azithromycin and pyrimethamine for the treatment of toxoplasmic encephalitis in AIDS

OBJECTIVE

To assess the safety, tolerance and activity of increasing doses of azithromycin in combination with pyrimethamine for the treatment of toxoplasmic encephalitis (TE) in patients with AIDS.

DESIGN

A phase I/II dose-escalation study of oral azithromycin in combination with pyrimethamine.

SETTING

Eight clinical sites in the United States.

PATIENTS

Forty-two adult HIV-infected patients with confirmed or presumed acute TE.

METHODS

Patients were enrolled into three successive cohorts receiving azithromycin 900, 1200 and 1500 mg a day with pyrimethamine as induction therapy. The induction period was 6 weeks followed by 24 weeks of maintenance therapy.

MAIN OUTCOME MEASURES

Patient response was evaluated clinically and radiologically.

RESULTS

Of the 30 evaluable patients, 20 (67%) responded to therapy during the induction period. Ten experienced disease progression. Of the 15 patients who received maintenance therapy, seven (47%) relapsed. Six patients discontinued treatment during the induction period as a result of reversible toxicities. Treatment-terminating adverse events occurred most frequently among the patients receiving the 1500 mg dose.

CONCLUSION

The combination of azithromycin (900-1200 mg a day) and pyrimethamine may be useful as an alternative therapy for TE among patients intolerant of sulfonamides and clindamycin, but maintenance therapy with this combination was associated with a high relapse rate. The combination was safe, but low-grade adverse events were common.

Usefulness of an individualized balance and gait intervention programme based on the problem-oriented assessment of mobility in nursing home residents

PURPOSE

To examine the usefulness of an individualized balance and gait training proramme according to the specific problems identified from the problem-oriented assessment of mobility (POAM) in residents of a nursing home.

METHOD

The clinical records of 74 NH residents (49 female, 25 male) who were consecutively referred to physical therapy for problems related to poor balance or gait or a recent fall in a 2 year period were reviewed retrospectively for the study. According to the medical charts, patients had received a four week (20 sessions) problem-oriented exercise programme that specifically targeted balance and gait deficits identified from the POAM and the retest had been done after four weeks of training.

RESULTS

The mean initial and final balance scores were 8.47+/-3.80. and 10.77+ /-3.37. respectively, and the mean gait scores were 6.73+/-2.30 initially and 7.71+/-1.95 finally. A Wilcoxon signed-rank comparison of the initial and final POAM indicated that significant improvement occurred in the balance scores (Z = 5.345, p < 0.0001) and the gait scale (Z = 3.589, p < 0.0001) in this group. Item analysis demonstrated the number of patients who improved or did not change on individual items.

CONCLUSIONS

Both balance and gait were significantly improved after a four-week intervention programme based on the deficits identified by POAM. The POAM is a useful tool to guide the clinician to target specific balance and gait deficits for individual nursing home elders.

Significance of hematuria in patients with interstitial cystitis: review of radiographic and endoscopic findings

OBJECTIVES

Hematuria may be found in up to 30% of patients with interstitial cystitis (IC). However, few studies have described its etiology based on the findings of a complete evaluation. We reviewed the clinical significance of hematuria in the setting of IC.

METHODS

We retrospectively reviewed the records of 148 patients fulfilling the National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases inclusion criteria for IC. Patients with gross or microscopic hematuria were identified. Evaluation consisted of urine culture and cytology, cystoscopy, and intravenous urography (or retrograde pyelography plus renal ultrasound). Patients with urinary tract infections were excluded.

RESULTS

Of 148 patients, 60 (41%) were found to have had at least one episode of hematuria during a mean follow-up of 18 months. Of 56 patients who agreed to be evaluated, 8 (14%) had positive urologic findings. Of these, none were highly significant; five were simple renal cysts (8.9%), one was a renal stone (1.8%), one was reflux nephropathy (1.8%), and one was medullary sponge kidney (1.8%). Cystoscopy, cytology, and bladder biopsy did not demonstrate malignancy in any patient. No statistically significant differences were found in age (49.9 versus 46.7 years), sex (90% versus 91% female), bladder capacity (792 versus 808 mL), and the presence of Hunner's ulcers (5% versus 2.4%), glomerulations (60% versus 59.9%), or detrusor mastocytosis (55% versus 47.6%) between patients with hematuria and those without (P >0.05).

CONCLUSIONS

The incidence of hematuria in patients with IC may be higher than previously reported. Nevertheless, although many of these patients present with pelvic pain and irritative voiding symptoms, the hematuria evaluation is unlikely to reveal a life-threatening urologic condition.

Assembly of very low density lipoproteins in mouse liver: evidence of heterogeneity of particle density in the Golgi apparatus

The assembly of very low density lipoproteins (VLDL) by hepatocytes is believed to occur via a two-step process. The first step is the formation of a dense phospholipid and protein-rich particle that is believed to be converted to VLDL by the addition of bulk triglyceride in a second step. Previous studies in our laboratory led us to hypothesize a third assembly step that occurs in route to or in the Golgi apparatus. To investigate this hypothesis, nascent lipoproteins were recovered from Golgi apparatus-rich fractions isolated from mouse liver. The Golgi fractions were enriched 125-fold in galactosyltransferase and contained lipoprotein particles averaging approximately 35 nm in diameter. These lipoproteins were separated by ultracentrifugation into two fractions: d < 1.006 g/ml and d1.006;-1.210 g/ml. The d < 1.006 g/ml fraction contained apolipoprotein B-100 (apoB-100), apoB-48, and apoE, while the d1.006;-1.210 g/ml fraction contained these three apoproteins as well as apoA-I and apoA-IV. Both fractions contained a 21-kDa protein that was isolated and sequenced and identified as major urinary protein. Approximately 50% of the apoB was recovered with the denser fraction. To determine if these small, dense lipoproteins were secreted without further addition of lipid, mice were injected with Triton WR1339 and [(3)H]leucine, and the secretion of apoB-100 and apoB-48 into serum VLDL (d < 1.006 g/ml) and d1.006;-1.210 g/ml fractions was monitored over a 2-h period. More than 80% of the newly synthesized apoB-48 and nearly 100% of the apoB-100 were secreted with VLDL. These studies provide the first characterization of nascent lipoproteins recovered from the Golgi apparatus of mouse liver. We conclude that these nascent hepatic Golgi lipoproteins represent a heterogeneous population of particles including VLDL as well as a population of small, dense lipoproteins. The finding of the latter particles, coupled with the demonstration that the primary secretory product of mouse liver is VLDL, suggests that lipid may be added to nascent lipoproteins within the Golgi apparatus.

Developmental ontogeny of NAD+ kinase in the rat conceptus

The ubiquitous NAD+ kinase (NADK) is the only known enzyme to catalyze formation of NADP+ from NAD+. The capacity to maintain an adequate supply of NADP(H) has important implications for development because of its requirement as a cofactor and electron donor in biosynthesis and detoxication reactions. Modulation of NADK may directly influence NADP(H) concentrations and cell sensitivity to embryotoxicants. Measurable activities of NADK were not detected in gestational day (GD) 10 rat conceptuses. By GD 11, specific activities of 1.8 and 7.0 pmol NADP+/min/microg protein were measured in embryos and visceral yolk sacs (VYSs), respectively. The VYS specific activities decreased thereafter to 0.5 pmol NADP+/min/microg protein by GD 18. Specific activities of NADK in placenta increased from 1.3 pmol NADP+/min/microg protein on GD 11 to 32.7 pmol NADP+/min/microg protein on GD 15. Specific activities in the liver increased from 1.7 pmol NADP+/min/microg protein on GD 15 to 51.1 pmol NADP+/min/microg protein on GD 21. NADK specific activities were also determined in other developmentally relevant tissues such as the heart and the brain. In the heart, NADK activity was at its lowest just before birth while in the brain it peaked at 5.4 pmol NADP+/min/microg protein just prior to birth. In the lung, activity increased from 0.9 pmol NADP+/min/microg protein on GD 17 to 5.9 pmol NADP+/min/microg protein on GD 21. However, activities dropped in the kidney from 2.0 pmol NADP+/min/microg protein on GD 17 to 1.1 pmol NADP+/min/microg protein on GD 21. These results demonstrate dramatic temporal and spatial variations in NADK activity. Tissue variations in NADK activities may reflect alterations in functional needs for cofactors during differentiation and a cooperation between tissues to optimize detoxification capacity. This is particularly important when chemical exposure during pregnancy disrupts pyridine nucleotide redox status and the conceptus must rely on NADK to provide additional NADP(H).

Renal effects of COX-2-selective inhibitors

Although nonsteroidal anti-inflammatory drugs (NSAIDs) effectively treat a variety of inflammatory diseases, these agents may cause deleterious effects on kidney function, especially with respect to solute homeostasis and maintenance of renal perfusion and glomerular filtration. NSAIDs act by reducing prostaglandin biosynthesis through inhibition of cyclooxygenase (COX) which exists as two isoforms (COX-1 and COX-2). NSAID-induced gastrointestinal toxicity is generally believed to occur through blockade of COX-1 activity, whereas the anti-inflammatory effects of NSAIDs are thought to occur primarily through inhibition of the inducible isoform, COX-2. However, the situation in the kidney may be somewhat different. Recent studies have demonstrated that COX-2 is constitutively expressed in renal tissues of all species; this isoform may, therefore, be intimately involved in prostaglandin-dependent renal homeostatic processes. Drugs that selectively inhibit COX-2 might, therefore, be expected to produce effects on renal function similar to nonselective NSAIDs which inhibit both COX-1 and COX-2. This assertion is borne out by recent clinical studies showing that the COX-2 inhibitors rofecoxib and celecoxib procedure qualitative changes in urinary prostaglandin excretion, glomerular filtration rate, sodium retention, and their consequences similar to nonselective NSAIDs. It, therefore, seems unlikely that these COX-2 inhibitors (and perhaps their successors) will offer renal safety benefits over nonselective NSAID therapies, and, at this juncture, it is reasonable to assume that all NSAIDs, including COX-2-selective inhibitors, share a similar risk for adverse renal effects.

If students are not customers, what are they?

The answers to questions about the relationship between faculty and students-including medical students-depend on an understanding of the nature of teaching and the underlying ethical principles of our society. The authors maintain that teaching is purposive, rational, communal, and moral. They assert that Western society is based on the values of liberal democracy and that the key ethical principles for the professions that are derived from those values are autonomy, standard of care, and respect for democratic institutions. There are three candidates for ethical models on which to base the relationship between students and faculty. Two of them (clientism and paternalism) the authors reject. The one that they favor (the fiduciary model) is based on mutual trust and respect, which both students and faculty have responsibilities to maintain. Using that model, the authors conclude that students are, in some aspects, customers of faculty. This student-centered approach is balanced by treating society and other faculty as customers as well. Pathologies in medical education attributed to clientism (such as an obsession with marks and overemphasis on memorization) existed well before medical students were purportedly being treated as customers; perhaps it is not the student who is "broken" but the system in which the student is made to function. Whether students are called customers, clients, knowledge workers, or simply students, faculty must involve them more in shaping their education and in dealing with enduring problems that profoundly affect their learning.

Dominant negative mutation of the hematopoietic-specific Rho GTPase, Rac2, is associated with a human phagocyte immunodeficiency

Rho GTPases control a variety of cellular processes, including actin polymerization, integrin complex formation, cell adhesion, gene transcription, cell cycle progression, and cell proliferation. A patient is described who has recurrent infections and defective neutrophil cellular functions similar to those found in Rac2-deficient mice. Molecular methods were used to clone the expressed Rac2 cDNA from this patient, and a single base pair change (G-->A at nucleotide 169) in the coding sequence was identified. This results in an asparagine for aspartic acid mutation at amino acid 57 (D57N), a residue that is involved in nucleotide binding and is conserved in all mammalian Rho GTPases. The cloned cDNA was then introduced into normal bone marrow cells through retrovirus vectors, and neutrophils expressing this mutant exhibited decreased cell movement and production of superoxide in response to fMLP. The expressed recombinant protein was also analyzed biochemically and exhibited defective binding to GTP. Functional studies demonstrated that the D57N mutant behaves in a dominant-negative fashion at the cellular level. The syndrome of Rac2 dysfunction represents a human condition associated with mutation of a Rho GTPase and is another example of human disease associated with abnormalities of small G protein signaling pathways. (Blood. 2000;96:1646-1654)

Cost-benefit analysis of extended antifungal prophylaxis in ventricular assist devices

This report defines the cost and benefit of extended antifungal prophylaxis in ventricular assist device (VAD) patients (pts). Extended antifungal prophylaxis is defined as prophylaxis with fluconazole or nystatin that is given until pts are extubated and off antibiotics. These data are compared with that obtained from earlier VAD patients who only received anti-fungal drugs for documented fungal colonization or infection. Thirty-six patients had HeartMate (n = 15) or Thoratec (n = 21) VADs between 1989 and 1997. Cultures positive for fungus (n = 52 cultures) were obtained from 16 of 36 patients (44% of patients). Forty-three fungal cultures were in the preprophylaxis and nine in the postprophylaxis era. There was one death attributable to fungal sepsis in the preprophylaxis era and none in the postprophylaxis era. The total cost of antifungal drugs in the preprophylaxis era was $3,840 over 1,498 patient days (PD) (mean $2.56 per PD), versus $70,670 over 1,525 PD in the postprophylaxis era (mean $46.34 per PD). Extended antifungal prophylaxis was not cost effective in VAD patients at this institution. However, short-term perioperative antifungal prophylaxis was not addressed by this study. We are now using short-term antifungal prophylaxis with fluconazole and nystatin in VAD patients because of the potential for serious morbidity and mortality that is associated with fungal device infections. A future analysis will determine the usefulness of this change in strategy.

Work, psychological well-being and performance

Evidence is reviewed on work performance as a consequence of both psychological well-being and work stressors. There is evidence that some forms of psychological well-being are related to subsequent in-role performance, although the evidence for a causal influence of work stressors on job performance is much weaker. There is also evidence for relationships between some job stressors or well-being and organizational citizenship behaviours. In general, research conducted at the individual level, indicates only weak or provisional relationships. A small number of recent studies indicate stronger associations between average levels of well-being in an organization and organizational performance. It is concluded that more detailed and specific models of well-being and work performance need to be developed. These models need to be tested using methods that can more easily detect subtle variations in well-being and work performance.

Sensitivity of a clinical scale of balance and gait in frail nursing home residents

PURPOSE

The purpose of this paper was to describe this application, and to assess the sensitivity of the application when evaluating clinical interventions for improving balance and gait.

METHODS

The records of fifteen consecutive patients referred to physical therapy for mobility problems or recent falls were reviewed for this study. The subjects were evaluated upon initial referral to physical therapy and after 30 days of treatment. Treatment was developed around the problems noted on initial evaluation and applied 5 days/week for 20 sessions.

RESULTS

A Wilcoxon signed-rank comparison of the initial and 30 day re-evaluation of the balance and the gait assessment indicated that significant improvement had occurred in the balance scores (Z = -3.20, p = 0.001) and the gait scores (Z = -2.82, p = 0.005) in this group.

CONCLUSION

These assessments are sensitive to clinical improvements in mobility among frail elders.

Concentrations of suspended particulate organic carbon in the tidal Yorkshire Ouse River and Humber Estuary

Data are presented for particulate organic carbon (POC) and particulate nitrogen (PN) concentrations in the Humber Estuary and tidal River Ouse Estuary. The POC data were derived from approximately monthly surveys and are consistent with data reported for suspended particulate matter (SPM) in the non-tidal River Ouse (the freshwater river) and with SPM, or bed sediments, in estuarine ecosystems such as the Mississippi, Delaware, San Francisco Bay, Tolo Harbour, the Vellar Estuary and Cochin Backwater, as well as the Loire, Gironde, Ems and Tamar Estuaries. Relative to the dry weight of SPM, the Humber-averaged organic carbon and nitrogen percentages during the year February 1995-March 1996 were 2.6 +/- 0.6% (mean and S.D.) and 0.21 +/- 0.04%, respectively. The ratio of Humber-averaged POC to Humber-averaged PN was 13 +/- 3. Higher POC levels were observed near the Humber's mouth and in the adjacent coastal zone during 'bloom' conditions, and in the upper estuarine reaches during large, winter and springtime freshwater inflows. At these times of high runoff, the POC content of SPM increased progressively up-estuary from the coastal zone to the tidal River Ouse. When inflows became very low, during late spring to early autumn of 1995, both the freshwater-saltwater interface (FSI) and the strengthening turbidity maximum (TM) moved further up-estuary and the POC content of SPM in the upper reaches of the Ouse became lower compared with that immediately down-estuary. This led to a poorly defined POC maximum near the confluence of the Humber, Ouse and Trent, before POC eventually decreased again towards the coastal zone. The lower POC contents in the upper estuarine reaches of the tidal Ouse may have been partly due to POC respiration by heterotrophic bacteria attached to SPM within the TM, consistent with the severe oxygen depletion observed there during high turbidity, summertime spring tides.

Seasonal variability of salinity, temperature, turbidity and suspended chlorophyll in the Tweed Estuary

Results are presented from a campaign of measurements that were undertaken to examine seasonal variability in physical and chemical fluxes and processes within the Tweed Estuary during the period September 1996-August 1997. The study utilised monthly surveys, each of approximately 1 week duration. This article interprets a subset of the salinity, temperature, turbidity [suspended particulate matter (SPM) levels] and chlorophyll a data. Measurements discussed here were obtained throughout the estuary during high-speed transects that covered the region between the tidal river and the coastal zone. Longitudinal distributions of surface salinity depended strongly on freshwater runoff. During high runoff the surface salinity was low and the freshwater-saltwater interface (FSI) was located close to the mouth. The reverse was true at times of low runoff. Salinity stratification was generally strong. During the surveys, river runoff temperatures ranged from approximately 2 to 18 degrees C and coastal waters (approximately 33 salinity) from approximately 6 to 15 degrees C. Turbidity was low throughout the campaign (SPM < 30 mg l(-1)). Because of rapid flushing times (one or two tides), turbidity tended to mix conservatively between river and coastal waters. Higher coastal turbidity was associated with stronger wind events, and higher fluvial turbidity with spate events. Suspended chlorophyll a levels were usually low throughout the estuary (typically < 2 microg l(-1)) and showed large spatial variability. Because of the rapid flushing of the estuary, it is hypothesised that it was not possible for several algal cell divisions to occur before algae were flushed to the coastal zone. A 'bloom' occurred during the May 1997 survey, when chlorophyll a levels reached 14 microg l(-1). Higher chlorophyll a concentrations at that time occurred at very low salinities, indicating that these waters and algae were largely fluvially derived, and may have resulted from increasing springtime solar irradiation.

Comparison of open, percutaneous, and translaryngeal tracheostomies

INTRODUCTION

With 3 tracheostomy techniques currently available, controversy exists regarding which is safest and most economical. Percutaneous (PDT) and the new translaryngeal (TLT) tracheostomies are cited as more cost-effective than the traditional open surgical procedure because they are bedside techniques. Our objective was to compare the perioperative and postoperative complications of the 3 techniques.

STUDY DESIGN

This was a prospective trial involving 100 consecutive patients who underwent tracheostomy between April and December of 1997 at the London Health Sciences Centre and St Joseph's Health Centre in London, Canada.

RESULTS

Fifty open tracheostomies were performed. Indications included prolonged ventilation (n = 42), airway protection (n = 5), pulmonary hygiene (n = 2), and sleep apnea (n = 1). A tension pneumothorax was the one significant intraoperative complication. Fifteen postoperative complications occurred, most notable of which was a 2-L hemorrhage at 24 hours. Thirty-seven TLTs were performed, 20 in patients with coagulopathy. Indications were prolonged intubation (n = 27), airway protection (n = 9), and pulmonary hygiene (n = 1). One intraoperative complication of accidental decannulation occurred. One postoperative complication, a pretracheal abscess, occurred in a decannulated transplant patient 2 weeks after the procedure. Thirteen PDTs were performed. Indications were prolonged intubation (n = 6), airway protection (n = 6), and tracheal toilet (n = 1). No significant complications occurred.

CONCLUSIONS

TLT and PDT have fewer complications than the traditional open technique. TLT appears to have the greatest utility in the coagulopathic patient.

Abnormal supranuclear eye movements in the child: a practical guide to examination and interpretation

Abnormal eye movements in the infant or voting child can be congenital or acquired. They may be a result of abnormal early visual development or a sign of underlying neurologic or neuromuscular disease. It is important to be able to detect these abnormalities and to distinguish them from normal but immature eye movements. The spectrum of disease in children differs from that in adults. Serious, potentially fatal but treatable disorders can be acquired in infancy, and abnormal eye movements in a sometimes apparently well child should never be labeled as congenital or benign without careful investigation. Eye movement analysis can indicate the presence of an underlying condition and help the clinician to classify different neurologic diseases. It is important to carefully examine the ocular motor system in any children at risk of neurologic disease. This review provides a practical guide to the examination and interpretation of eye movements in the child and includes recent literature on eye movement disorders of childhood. We describe supranuclear abnormalities of the ocular motor system in the order in which we would normally examine it: saccades, pursuit, convergence, vestibulo-ocular reflex, and optokinetic nystagmus. Nystagmus, internuclear ophthalmoplegia, cranial nerve abnormalities, and "miswiring" phenomena (such as Duane's syndrome and synergistic divergence) are not discussed.