Elevated risk of carrying gentamicin-resistant Escherichia coli among U.S. poultry workers

BACKGROUND

Antimicrobial use in food-animal production is an issue of growing concern. The application of antimicrobials for therapy, prophylaxis, and growth promotion in broiler chicken production has been associated with the emergence and dissemination of antimicrobial-resistant enteric bacteria. Although human exposure to antimicrobial-resistant bacteria through food has been examined extensively, little attention has been paid to occupational and environmental pathways of exposure.

OBJECTIVE

Our objective was to measure the relative risk for colonization with antimicrobial-resistant Escherichia coli among poultry workers compared with community referents.

METHODS

We collected stool samples and health surveys from 16 poultry workers and 33 community referents in the Delmarva region of Maryland and Virginia. E. coli was cultured from stool samples, and susceptibility to ampicillin, ciprofloxacin, ceftriaxone, gentamicin, nitrofurantoin, and tetracycline was determined for each E. coli isolate. We estimated the relative risk for carrying antimicrobial-resistant E. coli among poultry workers compared with community referents.

RESULTS

Poultry workers had 32 times the odds of carrying gentamicin-resistant E. coli compared with community referents. The poultry workers were also at significantly increased risk of carrying multidrug-resistant E. coli.

CONCLUSIONS

Occupational exposure to antimicrobial-resistant E. coli from live-animal contact in the broiler chicken industry may be an important route of entry for antimicrobial-resistant E. coli into the community.

Neurologic Symptoms and Neuropathologic Antibodies in Poultry Workers Exposed to Campylobacter jejuni

OBJECTIVES

To examine associations between occupational exposure to live poultry with Campylobacter exposure, Campylobacter-associated neurologic symptoms, and neuropathologic antibodies.

METHODS

Questionnaires, serum samples, and stool specimens were collected from 20 poultry workers and 40 community referents. Campylobacter exposure was evaluated by stool culture and serum antibodies; neurologic symptoms were assessed by questionnaire; and neuropathologic antibodies were measured by serum anti-glycolipid antibody concentrations.

RESULTS

Poultry workers had significantly higher anti-Campylobacter immunoglobulin G titers compared with that of referents (P < 0.05); they were significantly more likely to report multiple Campylobacter-associated neurologic symptoms; and male poultry workers had a higher point risk estimate for detectable neuropathologic anti-glycolipid immunoglobulin G titers (P = 0.07) compared with male referents.

CONCLUSIONS

These data suggest that poultry workers are at elevated risk of Campylobacter exposure and may be at elevated risk for Campylobacter-associated neurologic sequelae.

The effectiveness of large household water storage tanks for protecting the quality of drinking water

Many communities along the US-Mexico border remain without infrastructure for water and sewage. Residents in these communities often collect and store their water in open 55-gallon drums. This study evaluated changes in drinking water quality resulting from an intervention that provided large closed water storage tanks (2,500-gallons) to individual homes lacking a piped water supply. After the intervention, many of the households did not change the source of their drinking water to the large storage tanks. Therefore, water quality results were first compared based on the source of the household's drinking water: store or vending machine, large tank, or collected from a public supply and transported by the household. Of the households that used the large storage tank as their drinking water supply, drinking water quality was generally of poorer quality. Fifty-four percent of samples collected prior to intervention had detectable levels of total coliforms, while 82% of samples were positive nine months after the intervention (p < 0.05). Exploratory analyses were also carried out to measure water quality at different points between collection by water delivery trucks and delivery to the household's large storage tank. Thirty percent of the samples taken immediately after water was delivered to the home had high total coliforms (> 10 CFU/100 ml). Mean free chlorine levels dropped from 0.43 mg/l, where the trucks filled their tanks, to 0.20 mg/l inside the household's tank immediately after delivery. Results of this study have implications for interventions that focus on safe water treatment and storage in the home, and for guidelines regarding the level of free chlorine required in water delivered by water delivery trucks.

Carbon monoxide exposure in households in Ciudad Juárez, México

This study assessed exposure to carbon monoxide from gas and wood heater emissions in a sample of 64 households in peri-urban residential areas in Ciudad Juárez, Chihuahua, México. Indoor and outdoor carbon monoxide concentrations and temperatures were monitored for a continuous period of 1 week at 1 and 6-min intervals, respectively. The moving average carbon monoxide concentrations were compared to the World Health Organization (WHO) standards for carbon monoxide. Sixty-seven percent of households with gas heaters and 60% of households with wood heaters exceeded a health-based standard at some point during the monitoring. The difference between indoor and outdoor temperatures was modestly correlated with average carbon monoxide exposure (r=0.35, p-value <0.01). Heater type may be a stronger determinant of exposure, as households with a particular heater model (the El Sol FM-210) were significantly more likely to be among the more highly exposed households (odds ratio of 4.8, p-value of 0.02). A variety of health effects were pooled and found at elevated frequency in the households that exceeded the 8-h standard of 9ppm (odds ratio=5.1, p-value=0.031). These results highlight the need for further efforts to identify and mitigate potentially hazardous carbon monoxide exposures, particularly in moderate-income countries with cooler climates.

Growth promoting antibiotics in food animal production: an economic analysis

OBJECTIVE

Considerable controversy persists regarding the use of human antibiotics to promote growth in animals raised for food. The authors examined the economic effect of removing antibiotics used for growth promotion in commercial broiler chickens.

METHODS

The authors utilized data published by the Perdue company, the fourth largest poultry producer in the United States, in which a non-randomized controlled trial of growth-promoting antibiotic (GPA) use was conducted with seven million broiler chickens to evaluate the impact of removing GPAs on production.

RESULTS

Positive production changes were associated with GPA use, but were insufficient to offset the cost of the antibiotics. The net effect of using GPAs was a lost value of 0.0093 dollars per chicken (about 0.45% of total cost). Based upon these data, the authors found no basis for the claim that the use of GPAs lowers the cost of production. Note that this study does not include veterinary cost changes or changes in performance variability associated with the removal of GPAs.

CONCLUSIONS

This economic analysis is the first study to the authors' knowledge utilizing large-scale empirical data collected by U.S. industry, in which it is demonstrated that the use of GPAs in poultry production is associated with economic losses to the producers. These data are of considerable importance in the ongoing national debate concerning the continued use of antibiotics for growth promotion of food animals. Based on the industry study and the resulting economic impact, the use of GPAs in U.S. poultry production should be reconsidered.

The In-Home Environment and Household Health: A Cross-Sectional Study of Informal Urban Settlements in Northern México

People living in poverty make up nearly half of the global population and a large proportion of these individuals inhabit cities, living in informal settlements. However, only limited research on in-home environmental exposures and the associated health effects in these communities is available. This research investigates the home environment in unplanned settlements of a rapidly growing city on the U.S.-México border and its impact on the health of households with children under 12 years of age. A cross-sectional design was used to assess household exposures and health outcomes at the household level. A total of 202 households were selected from two informal settlements in the peri-urban region of Ciudad Juárez, México. The following variables were significantly associated with the report of at least one household member experiencing a health outcome in a two week period. Allergies were positively associated with insecticide use inside the home (adjusted Relative Odds (RO), 2.71; 95% confidence interval (CI), 1.2-6.3). Respiratory problems were associated with households using a wood burning stove vs. a gas stove (adjusted RO, 5.64; 95% CI, 1.1-27.9). Diarrhea was negatively associated with presence of a flush toilet in the home (adjusted RO, 0.22; 95% CI,0.1-0.6). Finally, eye irritations were positively associated with indoor tobacco smoke (adjusted RO, 2.23; 95% CI, 1.1-4.5). This research highlights exposures associated with poor living conditions in informal settlements and their associations with detrimental effects on health. More efforts should be made to understand the dynamics of poor urban environments including the health effects of exposures linked with poor housing conditions.

Arsenic: a roadblock to potential animal waste management solutions

The localization and intensification of the poultry industry over the past 50 years have incidentally created a largely ignored environmental management crisis. As a result of these changes in poultry production, concentrated animal feeding operations (CAFOs) produce far more waste than can be managed by land disposal within the regions where it is produced. As a result, alternative waste management practices are currently being implemented, including incineration and pelletization of waste. However, organic arsenicals used in poultry feed are converted to inorganic arsenicals in poultry waste, limiting the feasibility of waste management alternatives. The presence of inorganic arsenic in incinerator ash and pelletized waste sold as fertilizer creates opportunities for population exposures that did not previously exist. The removal of arsenic from animal feed is a critical step toward safe poultry waste management.

Magnetic resonance imaging of spongy degeneration of the central nervous system in a Labrador Retriever

A 7-month-old, neutered female Labrador Retriever was evaluated for tetraparesis and subtle cerebellar dysfunction. Clinical signs progressed over a period of 6 weeks to severe ataxia, hypermetria, intention tremors, and finally non-ambulatory tetraparesis. On magnetic resonance imaging of the brain there were large, bilaterally symmetrical, ovoid lesions in the region of the deep cerebellar nuclei that were hyperintense on T2-weighted and proton density images and hypointense on T1-weighted images. There were similar but smaller bilaterally symmetrical lesions present within the thalamus. Euthanasia was performed and lesions consistent with the previously described spongy degeneration of Labrador Retrievers were identified. This disease and its relation to similar human heritable leukodystrophies are discussed.

Computed radiography

CR is a useful tool for the equine veterinarian and has many advantages. Its only major disadvantage is the initial cost, in dollars and time, for setup in one's practice. CR is already in use at several universities and private practices in the United States and around the world. In the future, as is the case with any computer-based technology, this modality should become more affordable and readily available to smaller practices. The potential of CR in veterinary medicine combined with saturation of the human market is driving the development of specialized software and algorithms for veterinary medicine.

Quantitative hepatobiliary scintigraphy in normal cats and in cats with experimental cholangiohepatitis

Quantitative hepatobiliary scintigraphy using 99mTc-mebrofenin was performed on eight normal cats and on the same cats after induction of experimental cholangiohepatitis by infection with the liver fluke Platynosomum concinnum. Hepatobiliary scintigraphy was performed 3 times at 10 weeks, 4 months and 6 months after infection. In addition, routine biochemical tests, hepatic ultrasound and ultrasound guided hepatic biopsy samples were obtained at the same time points, and the results compared with hepatobiliary scintigraphy. The normal hepatic extraction fraction was determined to be 85%, and the normal hepatic excretion half time (T 1/2) was 14 minutes. There was no significant change in scintigraphic parameters compared to pre-infection values at any time following infection with the liver fluke. No correlation between scintigraphic parameters and histologic scores was found; however, significant correlation was identified between parasite burden and histologic scores 6 months following infection. Despite the presence of severe multifocal histologic abnormalities, minimal clinical, biochemical and scintigraphic derangements were identified using this model of cholangiohepatitis. Based on this study, hepatobiliary scintigraphy appears to be an insensitive test for structural hepatobiliary abnormalities. The role of hepatobiliary scintigraphy in functional hepatobiliary abnormalities of the feline liver has not been determined.

Esophageal transit of capsules in clinically normal cats

OBJECTIVE

To evaluate the esophageal passage of capsules in clinically normal cats and determine the incidence of prolonged transit or entrapment.

ANIMALS

12 clinically normal adult cats.

PROCEDURE

Esophageal transit of barium sulfate-filled capsules was evaluated fluoroscopically. Each cat was examined 3 times (36 examinations). Esophageal transit times were classified as normal (< or = 30 seconds) or prolonged (> 30 but < or = 240 seconds). Capsules were considered entrapped when transit times were > 240 seconds.

RESULTS

Transit times were normal in 10 of the 36 (27.8%) examinations, whereas times were prolonged in 7 (19.4%) examinations. Capsules became entrapped in the midcervical region of the esophagus during 19 (52.8%) examinations. Following termination of each examination, cats with entrapped capsules were fed a small amount (0.5 to 1 ounce) of food; this resulted in passage of the capsule to the stomach.

CONCLUSIONS AND CLINICAL RELEVANCE

The possibility of medication-induced esophagitis should be considered when orally administering ulcerogenic drugs to cats. It is recommended that a small volume of food be given following medications to ensure complete esophageal clearance.

Ultrasonographic features of canine gastrointestinal pythiosis

Pythiosis is a chronic pyogranulomatous infection of the gastrointestinal tract or skin caused by the water borne pathogen Pythium insidiosum. The ultrasonographic features of nine dogs with gastrointestinal pythiosis are reported. The stomach, duodenum, jejunum or colon were affected. All dogs had thickening of the gastrointestinal wall and areas with obliteration of the normal layered appearance. In one dog an eccentric mass was found arising from the serosal surface of the wall of the colon with mild diffuse wall thickening. Regional lymph node enlargement was seen in seven of the nine dogs. One dog had invasion of the pancreas and signs compatible with extrahepatic biliary obstruction. When compared to previous reports of gastrointestinal neoplasia, the features of wall thickening, loss of layering and regional lymphadenopathy are not considered specific for gastrointestinal pythiosis. Histological examination of tissue specimens is required for diagnosis.

Radiographic and ultrasonographic evaluation of the normal feline postpartum uterus

The radiographic and ultrasonographic appearance of the normal involution process of the feline postpartum uterus has not been previously described. Six queens were examined to determine the normal radiographic and ultrasonographic appearance of the involuting postpartum uterus. Radiographic and ultrasonographic examinations were performed daily from days one through ten, then on days 12, 14, 18, 24, and 28 postpartum. Radiographically the mean total uterine thickness was 16.5 mm at day one postpartum. By day 14 the mean total uterine thickness was 10.5 mm and by day 24 postpartum the uterus was not radiographically visible. Ultrasonographically at day one postpartum the mean total uterine thickness was 16.6 mm and the mean uterine wall thickness was 2.7 mm. At day 14 postpartum the mean total uterine thickness was 6.2 mm and the mean wall thickness was 2.1 mm. At day 28 postpartum the uterus could still be identified ultrasonographically however individual wall layers were not discernable.

Quantitative magnetic resonance imaging of the normal feline cranial abdomen

Magnetic resonance images of the cranial abdomen were acquired from 15 clinically normal cats. All cats had T1-weighted images, 8 cats had T2-images made and 7 cats had T1-weighted post Gd-DTPA images acquired. Signal intensity measurements for T1, T2, and T1 post contrast sequences were calculated for liver, spleen, gallbladder, renal cortex, renal medulla, pancreas, epaxial muscles, and peritoneal fat. On T1-weighted images the epaxial muscle had the lowest signal intensity, followed by renal medulla, spleen, renal cortex, pancreas, liver and fat, respectively. On T2-weighted images, epaxial muscle had the lowest signal intensity followed by liver, spleen, fat, and gallbladder lumen. Calculations of specific organ percent enhancement following contrast medium administration were made and compared with that reported in humans. A brief review of the potential clinical uses of MR in cats is presented.

Dynamic magnetic resonance imaging of the normal canine pituitary gland

The pituitary glands of six normal dogs were evaluated using dynamic magnetic resonance imaging. T1 weighted images were obtained every 13 seconds for three minutes of three contiguous slices through the pituitary gland following a bolus intravenous injection of gadolinium-DTPA. Contrast enhancement was seen initially in the region of the pituitary stalk at 52-65 seconds followed by uniform enhancement at 104-143 seconds post injection. This pattern of enhancement was seen in all subjects and is similar to that reported in humans.

Vertebral physitis with epiphyseal sequestration and a portosystemic shunt in a Pekingese dog

Vertebral physitis with bone sequestration and a portosystemic shunt were diagnosed in an 18-month-old female Pekingese dog. The latter was determined by the presence of low blood urea nitrogen, elevated serum bile acids, microhepatica and an increased portosystemic shunt fraction. It was managed with a home-cooked low protein diet. Vertebral physitis and bone sequestration was diagnosed by the presence of thoracolumbar hyperaesthesia, radiographic and scintigraphic changes, isolation of Staphylococcus intermedius from blood and the third lumbar vertebra, and histopathological examination of a surgical biopsy. A partial sequestrectomy was performed and a six-month course of amoxycillin-clavulanate was prescribed. The dog was pain-free and showed partial resolution of the radiographic signs four months after the discontinuation of antibiotics.

Assessment of barium impregnated polyethylene spheres (BIPS) as a measure of solid-phase gastric emptying in normal dogs--comparison to scintigraphy

Barium impregnated polyethylene spheres (BIPS) are radiopaque markers used for investigation of a variety of gastrointestinal disorders. One proposed use of the small (1.5 mm) marker is quantitative assessment of solid-phase gastric emptying, which may offer a simple, inexpensive alternative to nuclear medicine studies. In this study the rate and pattern of gastric emptying of a radiolabeled meal containing 30 small BIPS was evaluated in normal dogs by simultaneous comparison of the radiopaque marker method and a scintigraphic method. Serial scintigraphic images and radiographs were obtained for 8 hours or until 95% of the markers had left the stomach. Emptying curves were constructed and statistical analyses performed. There were significant differences in gastric emptying times and lag phase characteristics between the BIPS and scintigraphic studies. These results indicate that in normal dogs there are differences in both the rate and the pattern of solid-phase gastric emptying of a radiolabeled meal as assessed by scintigraphy and the gastric emptying of small BIPS.

Scintigraphic, sonographic, and histologic evaluation of renal autotransplantation in cats

OBJECTIVE

To determine scintigraphic, sonographic, and histologic changes associated with renal autotransplantation in cats.

ANIMALS

7 adult specific-pathogen-free cats: 5 males, 2 females, 1 to 9 years old.

PROCEDURE

Renal autotransplantation was performed by moving a kidney (5 left, 2 right) to the left iliac fossa. Before and at multiple times after surgery, for a total of 28 days, cats were evaluated by B-mode and Doppler ultrasonography, scintigraphy, and renal biopsy.

RESULTS

By 24 hours after surgery, a significant decrease (42%) in mean glomerular filtration rate (GFR) and an increase in mean renal size (81% increase in cross-sectional area) were evident in the transplanted kidney, compared with preoperative values. By postsurgery day 28, reduction in GFR was 23%. Significant changes in renal blood flow velocity were identified in both kidneys. Consistent changes in resistive index or pulsatility index for either kidney could not be identified. When all postoperative histologic data were combined, the histologic score, indicating degree and numbers of abnormalities detected, for the transplanted kidney was significantly higher than that for the control kidney.

CONCLUSIONS

Significant changes in renal function, size, and histologic abnormalities develop secondary to acute tubular necrosis in cats after uncomplicated renal autotransplantation.

CLINICAL RELEVANCE

Evaluation of renal size and function may be of benefit for clinical evaluation of feline renal transplant patients, whereas measurement of the resistive index may be of little clinical value.

Sonography of the normal feline gastrointestinal tract

The normal sonographic appearance of the stomach in various degrees of distension, the duodenum, the small intestine, and the large intestine was determined in awake and sedated cats. The mean stomach rugal fold thickness was 4.38 mm, and the interrugal thickness was 2.03 mm. No significant difference in stomach wall thickness was seen when the stomach was empty, half full, or full. The duodenal wall thickness was significantly greater than other parts of the small intestine, and this difference was accentuated by sedation (awake mean 2.4 mm; sedated mean 2.71 mm). The mean small intestinal wall thickness was 2.1 mm, and the mean colonic wall thickness was 1.67 mm. The five characteristic sonographic layers similar to that seen in the gastrointestinal tract of other species were routinely identified at all regions of the feline gastrointestinal tract.

Quantitative estimation of intestinal dilation as a predictor of obstruction in the dog

Mechanical obstruction is a major differential diagnosis for dogs presented with gastrointestinal problems. Small intestinal dilation is a cardinal sign of obstruction but its recognition depends upon the observer's experience and anecdotally derived parameters for normal small intestinal diameter. The objective of this study was to formulate a quantitative index for normal intestinal diameter and evaluate its usefulness in predicting small intestinal obstruction. The material consisted of survey abdominal radiographs of 50 normal dogs, 44 cases of intestinal obstruction and 86 patients which subsequently had an upper gastrointestinal examination. A ratio of the maximum small intestinal diameter (SI) and the height of the body of the fifth lumbar vertebra at its narrowest point (L5) was used, and a logistic regression model employed to determine the probability of an obstruction existing with varying degrees of intestinal dilation. A value of 1.6 for SI/L5 is recommended as the upper limit of normal intestinal diameter for clinical use. The model showed that obstruction is very unlikely if the SI/L5 value is less than this. Higher values were significantly associated with obstruction.

The dural tail sign in the diagnosis of meningiomas

In humans the dural tail is a sign seen on contrast enhanced T1 weighted magnetic resonance images. This finding is considered specific for meningioma. The purpose of this study was to determine how often the dural tail occurs in cats and dogs and whether it is a specific sign for meningiomas in these species. MR examinations for eighteen dogs and four cats with proven diagnoses were reviewed. Diagnoses included ten meningiomas (seven dogs and three cats), three gliomas, two pituitary tumors, single examples of two other tumor types and five patients with mass lesions due to inflammatory disease. Contrast enhanced T1 weighted images were evaluated independently by three of the authors for the presence of a dural tail, without knowledge of the diagnoses. The results were compared to the diagnosis for each patient and the performance of individual reviewers compared. When their results were averaged, the reviewers reported the presence of a dural tail in 6 of 10 (60%) meningiomas, although detection varied between observers from 40% to 80%. Each reviewer had one false positive result, two reported a dural tail with a chromophobe adenocarcinoma and one with a toxoplasma meningoencephalitis. When a dural tail is seen an associated mass is most likely a meningioma. It is uncertain whether the dural tail represents neoplastic infiltration beyond the margins of the meningioma. This should be considered when planning treatment.

Insulin lispro, a new insulin analog

Insulin lispro is a rapid-acting insulin analog to regular insulin. Inversion of the proline-lysine amino acid sequence at positions 28 and 29 on the B chain is responsible for its more rapid absorption, faster onset, and shorter duration of action compared with regular insulin. The fast onset of action allows for greater flexibility in dosing and mealtime scheduling. Insulin lispro provides equivalent or slightly improved glycemic control in patients with types I and II diabetes mellitus compared with regular insulin, without subsequent increases in hypoglycemic episodes. It also results in greater reduction in postprandial blood glucose excursion than regular insulin. Compared with other insulins, insulin lispro represents a more physiologic approach to exogenous insulin therapy.

Exploring the role of sulfonylureas in the treatment of non-insulin-dependent diabetes mellitus

For the last 30 years, sulfonylureas have been the mainstay of treatment for patients with non-insulin-dependent diabetes mellitus (NIDDM). They offered patients an alternative to using insulin to lower their blood glucose. One of the advantages of these agents was that they could be taken orally as opposed to insulin, which required multiple daily injections. In addition, they are tolerable, with few side effects, and they cause less hypoglycemia than does insulin. In the past year, new agents (metformin and acarbose) have been introduced into the market and have offered practitioners an alternative to the traditional sulfonylureas. The sulfonylureas are still valuable agents in the treatment of NIDDM. Their efficacy is unsurpassed by any other oral medications. They possess the best tolerability profile of all oral agents on the market, and they possess very few contraindications or drug interactions. The sulfonylureas should still be considered first-line agents for NIDDM. Metformin and acarbose are agents that may benefit a specific patient population, but sulfonylureas are agents that can benefit most patients.

Important aspects of self-management education in patients with diabetes

The Diabetes Control and Complications Trial has shown that the long-term complication of diabetes can be decreased with intensive glycemic control. However, comprehensive patient education is required to provide the patient with the self-management skills necessary to achieve this level of glycemic control. Epidemiologic data indicate that large numbers of patients do not receive the proper care or education necessary to develop such self-management abilities. In order to convey the importance of patient education, the American Diabetes Association (ADA) has labeled self-management education as a cornerstone of therapy for patients with diabetes. Standards of care have also been defined by the ADA. Within the current U.S. health care system, however, limitations are present that may affect the quality of care and ability to provide adequate patient education. Therefore, it is the responsibility of the health care provider to improve the education process in an attempt to maintain standards of care outlined by the ADA. When developing a diabetes self-management training program, the ADA national standards can be used as a guideline.

Sulfation of tyrosine residues increases activity of the fourth component of complement

Sulfation of tyrosine residues recently has been recognized as a biosynthetic modification of many plasma proteins and other secretory proteins. Effects of this site-specific modification on protein function are not known, but the activity of several peptides such as cholecystokinin is greatly augmented by sulfation. Here, we examine the role of sulfation in the processing and activity of C4 (the fourth component of complement), one of the few proteins in which sites and stoichiometry of tyrosine sulfation have been characterized. Our results, with C4 as a paradigm, suggest that sulfation of tyrosine residues can have major effects on the activity of proteins participating in protein-protein interactions. Sulfation of C4 synthesized by Hep G2 cells was blocked by incubating the cells with NaClO3 and guaiacol. These sulfation inhibitors did not alter secretion or other steps in the processing of C4. However, hemolytic activity of C4 was decreased more than 50%. The inhibitors' effect on C4 activity was prevented by adding Na2SO4 to restore sulfation of C4. Activity of C3, a complement component homologous to C4 but lacking tyrosine sulfate residues, was minimally reduced (19%) by the inhibitors. Decreased hemolytic activity of nonsulfated C4 apparently resulted from impaired interaction with complement subcomponent C1s (EC 3.4.21.42), the protease that physiologically activates C4. Purified C1s was able to cleave nonsulfated C4, but approximately 10-fold higher concentrations of C1s were required for that cleavage than to yield equivalent cleavage of sulfated C4. Our results suggest that activation of C4, a central component in the classical pathway of complement activation, is influenced by the level of sulfation of the protein. Thus, sulfation of C4 provides a potential locus for physiological or pharmacological modulation of complement-mediated opsonization and inflammation.

Comparative amnestic effects of benzodiazepine hypnotic agents

The effects of triazolam 0.5 mg and temazepam 30 mg on immediate and delayed recall in normal and insomniac subjects were evaluated in three separate, randomized, placebo-controlled, parallel group studies. Neither drug caused significant impairment of immediate recall. In the tests of delayed recall, triazolam caused a consistent anterograde amnestic effect. No significant impairment of delayed recall was observed in the temazepam study. Anterograde amnesia is thought to be a dose-related effect of benzodiazepines. Compounds with high benzodiazepine receptor affinity such as triazolam are thought to cause this type of amnesia more often than the lower-affinity compounds such as temazepam.

Sulfation of tyrosine residues does not influence secretion of alpha 2-antiplasmin or C4

Sulfation of tyrosine residues is a biosynthetic modification of many secretory proteins. The function of this modification is not known, but it has been proposed that tyrosine sulfate residues may act as sorting signals to direct proteins along the secretory pathway. We tested this hypothesis by examining the effect of sulfation inhibitors on the kinetics of secretion of proteins by HepG2 cells. The inhibitors induced no change in the rate of secretion of alpha 2-antiplasmin and C4 (fourth component of complement), both of which contain tyrosine sulfate residues. Sulfation of tyrosine residues does not contribute to secretion of these proteins.

Inhibitors of the sulfation of proteins, glycoproteins, and proteoglycans

Two categories of compounds, substrates of sulfation and sulfate analogs, were tested for the ability to inhibit sulfation of macromolecules secreted by HepG2 cells. Several compounds which most effectively inhibited sulfation without toxic effects on cells were tested for their relative inhibition of sulfation of tyrosine residues (using the fourth component of complement as a model substrate), of N-linked oligosaccharides (alpha 2HS-glycoprotein as substrate), and of proteoglycans. Inhibitors decreased the sulfation of all three classes of substrate, but not always equally. Use of inhibitors from both categories in combination yielded synergistic effects, with more effective inhibition of sulfation and low toxicity. Such combinations of inhibitors should provide a valuable tool for probing the significance of the sulfation of macromolecules.

Gene exchange and natural selection cause Bacillus subtilis to evolve in soil culture

Strains of Bacillus subtilis exchange linked blocks of genes when growing together in soil; such exchange leads to extensive reorganization of the genotypic structure of the population and to the appearance and eventual dominance of a single phenotype. This process illustrates how recombination and selection lead to adaptive changes in populations.

Pneumoperitoneum. A complication of mechanical ventilation

Pneumoperitoneum occurred in three adults receiving mechanical ventilatory support. Since the presence of a perforated viscus could not be confirmed by combinations of clinical, surgical, or autopsy findings in any of these patients, it appears that the free abdominal air in these patients was a complication of the ventilatory therapy. It is possible that such a complication may be more common than is currently recognized and thus should be added to the differential diagnosis of pneumoperitoneum.

Tumor emboli presenting as pulmonary hypertension. A diagnostic dilemma

A case of recurrent tumor emboli secondary to choriocarcinoma is described. The patient presented with obvious pulmonary hypertension and was diagnosed and treated as a case of multiple pulmonary embolism. Information which suggested the possibility of tumor emboli was indeed present but recognized only retrospectively.