Simultaneous concentration of Enterococci and coliphage from marine waters using a dual layer filtration system

Concentrating diverse microbes in a time and cost effective manner is an essential component in water quality monitoring of recreational beaches. Historically, detection of bacteria and viruses requires two different capture methods to detect both types of organisms in a given water sample. The purpose of this present study was to evaluate a newly devised dual layered filtration system, which was developed to simultaneously concentrate both viruses and bacteria in one step from marine waters. An apparatus was designed to accommodate two 90-mm diam., 0.45 microm pore size membranes in series, one on top of the other. The top polyvinylidene fluoride (PVDF) membrane was used to filter bacteria by physical straining while the bottom HA membrane retained viruses through adsorption. Results indicated that the dual layer filtration system recovered 83+/-14% of the test bacteria (Enterococcus fecalis) and 81+/-28% of the test virus (MS2 coliphage) on the top and bottom membranes, respectively. This research demonstrates the potential of using a dual layered filtration system for the simultaneous concentration of both bacteria and viruses on separate filters from recreational beach waters. This system is relatively simple to use, inexpensive, and has the potential to be suitable for routine monitoring. This study serves as a proof of concept for the technique. Additional experiments are needed to evaluate the system on a variety of different bacteria and viruses as well as on water with different physical and chemical parameters.

Sequential concentration of bacteria and viruses from marine waters using a dual membrane system

The ability to rapidly and effectively concentrate diverse microbes is an essential component for monitoring water quality at recreational beaches. The purpose of this study was to develop a 0.45 microm pore size dual membrane system, which can sequentially concentrate both viruses and bacteria. The top PVDF membrane was used to filter bacteria by physical straining while the bottom HA membrane retained viruses through adsorption. The recovery of this system was assessed using test organisms: enterococci and somatic coliphage. Volumes of 100 to 400 mL of unspiked and sewage-spiked beach water were filtered through both types of membranes. The PVDF membrane recovered statistically equivalent amounts of enterococci when compared to traditional membranes. All of the coliphage passed through the PVDF membrane, while 22% passed through the HA membrane. Increasing the volume from 100 to 400 mL did not significantly influence recoveries. Up to 35% of coliphage was eluted from the bottom membrane using beef extract solution. Rinsing bottom membranes with 0.5 mmol L(-1) H(2)S0(4) was found to deactivate somatic coliphage. This research demonstrates the potential of using a dual membrane adsorption system for the concentration of both bacteria and viruses from recreational beaches. A proposed bi-layer filtration system can be designed for simultaneous bacteria and virus filtration. Future experiments should focus on measurements utilizing additional bacteria and viruses.

Intestinal parasites among young children in the interior of Guyana

Intestinal parasites contribute greatly to morbidity in developing countries. While there have been several studies of the problem in the Caribbean, including the implementation of control programmes, this has not been done for Guyana. The aim of this study was to determine the prevalence of intestinal parasites among young children in a town located in the interior of Guyana. Eighty-five children under the age of 12 years were studied prospectively for intestinal parasites in Mahdia, Guyana. Stool samples were transported in formalin to the Department of Microbiology, The University of the West Indies, Jamaica, for analysis using the formalin-ether concentration and Ziehl-Neelsen techniques. Data on age and gender of the children were recorded on field data sheets. At least one intestinal parasite was detected in 43.5% (37/85) of the children studied and multiple parasitic infections were recorded in 21.2% (18/85). The most common intestinal helminth parasite was hookworm (28.2%; 24/85), followed by Ascaris lumbricoides (18.8%; 16/85) and then Trichuris trichuria (14.1%; 12/85). Among the protozoan infections Giardia lamblia was detected in 10.5% (9/85) of the study population while Entamoeba histolytica appeared rarely. All stool samples were negative for Cryptosporidium and other intestinal Coccidia. There was no predilection for gender with any of the parasites. The pattern of distribution of worms in this area of Guyana was unlike that seen in other studies. Hookworm infection was the most common among the children and a large proportion had multiple infections. The study established the occurrence and prevalence of a number of intestinal parasites in the population of Guyana. This sets the stage for the design and implementation of more detailed epidemiological studies.

Development of a protocol for monitoring status and trends in forest soil carbon at a national level

The national Forest Health Monitoring (FHM) program requires protocols for monitoring soil carbon contents. In a pilot study, 30 FHM plots loblolly shortleaf (Pinus taeda L./Pinus echinata Mill.) pine forests across Georgia were sampled by horizon and by depth increments. For total soil carbon, approximately 40% of the variance was between plots, 40% between subplots and 20% within subplots. Results by depth differed from those obtained by horizon primarily due to the rapid changes in carbon content from the top to the bottom of the A horizon. Published soil survey information overestimated bulk densities for these forest sites. The measurement of forest floor depths as a substitute to sampling did not provide reliable estimates of forest floor carbon. Precision of replicate samples was approximately 10-30% for field duplicates and 5-10% for laboratory duplicates. Based on national indicator evaluation criteria, sampling by depth using bulk density core samplers has been recommended for national implementation. Additional procedures are needed when sampling organic soils or soils with a high percentage of large rock fragments.

Identification of Anopheles aquasalis as a possible vector of malaria in Guyana, South America

Adult female mosquitoes were collected in Mahdia, Guyana, to determine the incidence of malaria in Anopheles species found during the month of June 2000. Centers for Disease Control miniature white (incandescent) light traps, model 512, and miniature black (ultraviolet) light traps, model 912, were used to capture female mosquitoes. Numbers of mosquitoes collected were compared between white and black light traps and between traps set outside and inside of buildings. Adult female Anopheles mosquitoes were identified and an ELISA dipstick test for Plasmodium vivax and Plasmodium falciparum was performed on each mosquito. An aquasalis, An oswaldoi, and An braziliensis were attracted to white light traps. An triannulatus and An darlingi were collected from black light traps. Approximately the same numbers of all female Anopheles mosquitoes 28/45 (62%) were caught inside buildings as outside. Numbers of female non-anopheles mosquitoes captured in light traps varied between the traps set outside of buildings and inside of buildings with bright light traps collecting 91/122 (75%). A total of 45 Anopheles mosquitoes were captured and 122 non-anopheles species. Of the two known vectors of malaria in Guyana, An darlingi mosquitoes were not infected with P vivax but An aquasalis was found to be a carrier. The findings of this study suggest a need for further surveying and identification of current malaria vectors in Guyana.

Laser-based microscopic approaches: application to cell signaling in environmental lung disease

Cell-imaging approaches using new laser-based technologies have a wide applicability to thefields of pathology and cell biology. Here, we present the application of several of these techniques, including confocal scanning laser microscopy (CSLM), laser scanning cytometry (LSC), and laser capture microdissection (LCM), to studies of cell signaling by environmental agents in lung disease. Using both cells in culture and lung tissue, we show that these technologies are powerful tools for understanding signal transduction cascades elicited by toxic agents, such as oxidants and asbestosfibers, and their relationship to the development of cell injury and proliferation, responses leading to lung disease and/or repair.

Gene structure and expression of phospholemman in mouse

Phospholemman (PLM) is a small transmembrane cardiac protein that is the major sarcolemmal substrate for phosphorylation in response to adrenergic stimulation. PLM likely plays a role in muscle contractility and cell volume regulation through its function as a channel or a channel regulator. We are the first to describe the structure of the PLM gene and to demonstrate PLM cDNA splice variants. We cloned the murine PLM cDNA and used it as a probe to isolate the gene from a 129/SvJ genomic library. The gene contains seven introns and eight exons. The coding sequence is interrupted by five introns; the 5' untranslated region by two. Using rapid amplification of 5' cDNA ends we identified transcription start sites and four splice variants of the 5' untranslated domain. There was no TATA box or CAAT box in the putative promoter regions. The gene has several stretches of dinucleotide repeats. The 3' untranslated domains of mouse PLM cDNA clones show sequence differences not accounted for by alternative splicing. Mouse PLM shares 93, 83 and 80% amino acid identity with rat, dog, and human PLMs, respectively. Tissue expression of murine PLM parallels that in other species, being highest in heart, skeletal muscle, and liver.

Sources of Escherichia coli in a coastal subtropical environment

Sources of Escherichia coli in a coastal waterway located in Ft. Lauderdale, Fla., were evaluated. The study consisted of an extensive program of field measurements designed to capture spatial and temporal variations in E. coli concentrations as well as experiments conducted under laboratory-controlled conditions. E. coli from environmental samples was enumerated by using a defined substrate technology (Colilert-18). Field sampling tasks included sampling the length of the North Fork to identify the river reach contributing high E. coli levels, autosampler experiments at two locations, and spatially intense sampling efforts at hot spots. Laboratory experiments were designed to simulate tidal conditions within the riverbank soils. The results showed that E. coli entered the river in a large pulse during storm conditions. After the storm, E. coli levels returned to baseline levels and varied in a cyclical pattern which correlated with tidal cycles. The highest concentrations were observed during high tide, whereas the lowest were observed at low tide. This peculiar pattern of E. coli concentrations between storm events was caused by the growth of E. coli within riverbank soils which were subsequently washed in during high tide. Laboratory analysis of soil collected from the riverbanks showed increases of several orders of magnitude in soil E. coli concentrations. The ability of E. coli to multiply in the soil was found to be a function of soil moisture content, presumably due to the ability of E. coli to outcompete predators in relatively dry soil. The importance of soil moisture in regulating the multiplication of E. coli was found to be critical in tidally influenced areas due to periodic wetting and drying of soils in contact with water bodies. Given the potential for growth in such systems, E. coli concentrations can be artificially elevated above that expected from fecal impacts alone. Such results challenge the use of E. coli as a suitable indicator of water quality in tidally influenced areas located within tropical and subtropical environments.

Seroepidemiology of Helicobacter pylori infection in a Jamaican community

We researched epidemiologic associations between environmental and demographic factors and prevalence of Helicobacter pylori infection in a suburban Jamaican community. Using a clustered sampling technique, 22 domestic yards enclosing 60 separate households were randomly selected from a local community. All household members (n = 346) were invited to participate following informed consent; the overall compliance rate was 58.9%. A commercial enzyme immunoassay (HMáCAP) was used to detect IgG antibodies raised against H. pylori. Environmental and demographic information was obtained by questionnaire. The seroprevalence of H. pylori was 69.9% (n = 202). Analysis of the independent variables revealed three major components: Component 1 described, collectively, good personal hygiene and sanitation, indoor water supply and absence of straying animals in the peridomestic area; Component 2 included older age, good personal hygiene and large yard size; Component 3 the presence of domestic animals (cats and dogs) and, again, large yard size. These three complexes explained 42.2% of the variability in the data set. Logistic regression showed that Components 2 and 3 were independently associated with H. pylori seropositivity, indicating that a combination of demographic, environmental and zoonotic factors is involved in the spread of H. pylori infections at the tropical community level.

Field evaluation of the Determine rapid human immunodeficiency virus diagnostic test in Honduras and the Dominican Republic

Rapid detection of human immunodeficiency virus (HIV) infection can result in improved patient care and/or faster implementation of public health preventive measures. A new rapid test, Determine (Abbott, Abbott Park, Ill.), detects HIV type 1 (HIV-1) and HIV-2 antibodies within 15 min by using 50 microl of serum or plasma. No specialized equipment or ancillary supplies are required, and results are read visually. A positive result is noted by the appearance of a red line. An operational control (red line) indicates proper test performance. We evaluated the Determine rapid HIV detection test with a group of well-characterized serum samples (CD4 counts and viral loads were known) and serum samples from HIV-positive individuals at field sites in Honduras and the Dominican Republic. In the field evaluations, the results obtained by the Determine assay were compared to those obtained by local in-country HIV screening procedures. We evaluated serum from 100 HIV-positive patients and 66 HIV-negative patients. All samples gave the expected results. In a companion study, 42 HIV-positive samples from a Miami, Fla., serum bank were tested by the Determine assay. The samples had been characterized in terms of CD4 counts and viral loads. Fifteen patients had CD4 counts <200 cells/mm(3), while 27 patients had CD4 counts >200 cells/mm(3). Viral loads ranged from 630 to 873,746 log(10) copies/ml. All samples from the Miami serum bank were positive by the Determine test. Combined results from the multicenter studies indicated that the correct results were obtained by the Determine assay for 100% (142 of 142) of the HIV-positive serum samples and 100% (66 of 66) of the HIV-negative serum samples. The Determine test was simple to perform and the results were easy to interpret. The Determine test provides a valuable new method for the rapid identification of HIV-positive individuals, especially in developing countries with limited laboratory infrastructures.

Dengue in Guyana

There have been dramatic increases in dengue fever (DF) and dengue haemorrhagic fever in South America. Guyana has reported less than five cases per year for most of the past decade. We evaluated patients in a clinic in Georgetown, Guyana, over 2 days and found evidence of 50 cases of dengue infection.

Total immunoglobulin E levels and dengue infection on San Andrés Island, Colombia

An evaluation of total immunoglobulin E (IgE) and dengue serostatus in 168 subjects from San Andrés Island, Colombia, revealed altered levels of IgE in 89% of the population. IgE levels were higher in patients with a history of dengue or with a current secondary or current primary infection than in subjects with no exposure (P = 0. 01). Dengue infection accounted for 23% of the variation in IgE levels.

Evaluation of the MRL diagnostics dengue fever virus IgM capture ELISA and the PanBio Rapid Immunochromatographic Test for diagnosis of dengue fever in Jamaica

We evaluated two new commercial dengue diagnostic tests, the MRL Diagnostics Dengue Fever Virus IgM Capture ELISA and the PanBio Rapid Immunochromatographic Test, on serum samples collected during a dengue epidemic in Jamaica. The MRL ELISA method correctly identified 98% (78 of 80) of the samples as dengue positive, while the PanBio test identified 100% (80 of 80). Both tests were 100% (20 samples of 20) specific.

Occurrence of Cryptosporidium oocysts and Giardia cysts in water supplies of San Pedro Sula, Honduras

During June 1996, water supplies of the city of San Pedro Sula, Honduras, were sampled to obtain an assessment of Cryptosporidium oocyst and Giardia cyst concentrations. Each sample was concentrated and stained with an indirect immunofluorescent antibody, and parasites were counted through microscopic analysis. In three surface water supplies, Cryptosporidium oocyst concentrations ranged from 58 to 260 oocysts per 100 L, and Giardia cysts were present in concentrations ranging from 380 to 2100 cysts per 100 L. Unlike the surface water samples, groundwater had a higher concentration of Cryptosporidium oocysts (26/100 L) than Giardia cysts (6/100 L), suggesting that the groundwater aquifer protects the water supply more effectively from larger Giardia cysts. Cryptosporidium oocyst concentrations are within the typical range for surface water supplies in North America whereas Giardia cyst concentrations are elevated. Efforts should be made to protect raw water from sources of contamination.

Epidemiology of giardiasis and cryptosporidiosis in Jamaica

We report the findings of a cross-sectional epidemiologic study of Giardia lamblia and Cryptosporidum infections in Jamaica. Three hundred twenty eight stool samples from patients less than one to 81 years of age were examined using formalin-ether concentration for G. lamblia, Zeihl-Neelsen staining for Cryptosporidium, and the Prospect rapid enzyme immunoassay (EIA; Alexon, Sunnyvale, CA) for parasite diagnosis. The Prospect Giardia rapid assay detected 17 cases of G. lamblia infection compared with six by formalin-ether concentration. However, the Prospect Cryptosporidum EIA did not increase the rate of detection of Cryptosporidum when compared with Zeihl-Neelsen staining. Cryptosporidum infections were most frequently diagnosed in children less than five years old and prevalence decreased with age. In contrast, the prevalence of giardiasis increased as children became older. There were no associations between the infections and stool consistency, clinical manifestations, or sex of the individuals. The contribution of the parasites to childhood morbidity will depend on accurate laboratory diagnosis.

Increased prevalence of Plasmodium falciparum malaria in Honduras, Central America

We report on our investigation of a malaria outbreak in Honduras, Central America, in January 1997. We tested 202 patients with fever and chills using thin and thick blood film microscopy. Sixteen patients lived in the city and the rest lived in rural areas. A total of 95 samples (47%) were positive for malaria parasites. Seventy-nine percent (63/80) of the rural patients were infected with Plasmodium vivax and 21% (17/80) were infected with P. falciparum. In the urban area, all 15 infected patients had P. vivax malaria and none showed evidence of P. falciparum. Since previous reports indicate that falciparum malaria accounts for only 2% of the overall malaria infections in Honduras, the results reported here suggest that there is a dramatic increase in falciparum malaria in the area of Honduras investigated in this study.

A review of practical techniques for the diagnosis of malaria

Malaria is a global health problem, responsible for nearly 3 million deaths each year, and on the increase worldwide. Improvements in malaria diagnostics should facilitate the identification of individuals infected with the malarial parasites and the treatment of such cases with appropriate drugs. Both traditional and contemporary methods for malaria diagnosis are the subjects of the present review. Traditional diagnosis, based on the examination of Giemsa-stained thick and thin blood smears under a microscope, is inappropriate for many areas because there are insufficient microscopes and/or trained microscopists to read and interpret the slides. Such traditional methods are discussed in the context of parasite quantification. Newer, more advanced malaria diagnostics are now available and the relative merits of methods based on fluorescent microscopy or the detection of nucleic acid (including PCR) are described, including comparisons of costs. Fluorescent microscopy and nucleic-acid techniques both require skills and equipment which are not universally available in many malaria-endemic countries. Recently introduced diagnostic tests based on immuno-assays solve this problem since they are easy to run and interpret, and do not require complex equipment or technical support. They are also rapid (< 10 min/test), cost-effective and at least as sensitive as traditional microscopy.

Intestinal parasitic infections in human immunodeficiency virus (HIV)-positive and HIV-negative individuals in San Pedro Sula, Honduras

Honduras has at least five-times more human immunodeficiency virus (HIV)-infected individuals than any other country in Central America. The relationship between HIV status and the presence of intestinal parasites in this part of the world is unknown. This study presents the results from a prospective, comparative study for the presence of parasites in 52 HIV-positive and 48 HIV-negative persons in San Pedro Sula, Honduras. Infection with HIV was determined by microagglutination and confirmed by Western blot analysis. Parasites were detected in stools using formalin-ether concentration, and Kinyoun and trichrome staining. Age, sex, and clinical state of HIV infection were recorded for each study participant. Our results indicate that Cryptosporidium parvum and Strongyloides stercoralis, which are intracellular or live in the mucosa, were found exclusively in persons infected with HIV. In comparison, the prevalence of the extracellular parasites Giardia lamblia, Ascaris lumbricoides, and Trichuris trichiura was significantly higher (P < 0.05) in persons who were HIV-negative. Trichuris worms are in contact with the gut epithelium and less so with the mucosa, whereas Strongyloides lives within the gut mucosa. It is possible that changes in the gut epithelium due to HIV infection do not affect the mucosa and therefore would not affect Strongyloides. We conclude that infection with HIV may selectively deter the establishment of certain intestinal parasites. This may be due to the fact that HIV-induced enteropathy does not favor the establishment of extracellular parasites. Intracellular and mucosal dwelling organisms, however, may benefit from pathologic changes and reduced local immune responses induced by the virus, which, in turn, may lead to higher prevalence among HIV-infected individuals.

Evaluation of the OptiMAL test for rapid diagnosis of Plasmodium vivax and Plasmodium falciparum malaria

The development of rapid and specific diagnostic tests to identify individuals infected with malaria is of paramount importance in efforts to control the severe public health impact of this disease. This study evaluated the ability of a newly developed rapid malaria diagnostic test, OptiMAL (Flow Inc., Portland, Oreg.), to detect Plasmodium vivax and Plasmodium falciparum malaria during an outbreak in Honduras. OptiMAL is a rapid (10-min) malaria detection test which utilizes a dipstick coated with monoclonal antibodies against the intracellular metabolic enzyme parasite lactate dehydrogenase (pLDH). Differentiation of malaria parasites is based on antigenic differences between the pLDH isoforms. Since pLDH is produced only by live Plasmodium parasites, this test has the ability to differentiate live from dead organisms. Results from the OptiMAL test were compared to those obtained by reading 100 fields of traditional Giemsa-stained thick-smear blood films. Whole-blood samples were obtained from 202 patients suspected of having malaria. A total of 96 samples (48%) were positive by blood films, while 91 (45%) were positive by the OptiMAL test. The blood films indicated that 82% (79 of 96) of the patients were positive for P. vivax and 18% (17 of 96) were infected with P. falciparum. The OptiMAL test showed that 81% (74 of 91) were positive for P. vivax and 19% (17 of 91) were positive for P. falciparum. These results demonstrated that the OptiMAL test had sensitivities of 94 and 88% and specificities of 100 and 99%, respectively, when compared to traditional blood films for the detection of P. vivax and P. falciparum malaria. Blood samples not identified by OptiMAL as malaria positive normally contained parasites at concentrations of less than 100/microl of blood. Samples found to contain P. falciparum were further tested by two other commercially available rapid malaria diagnostic tests, ParaSight-F (Becton Dickinson, Cockeysville, Md.) and ICT Malaria P.f. (ICT Diagnostics, Sydney, Australia), both of which detect only P. falciparum. Only 11 of the 17 (65%) P. falciparum-positive blood samples were identified by the ICT and ParaSight-F tests. Thus, OptiMAL correctly identified P. falciparum malaria parasites in patient blood samples more often than did the other two commercially available diagnostic tests and showed an excellent correlation with traditional blood films in the identification of both P. vivax malaria and P. falciparum malaria. We conclude that the OptiMAL test is an effective tool for the rapid diagnosis of malaria.

Prevalence of enterohemorrhagic Escherichia coli in raw and treated municipal sewage

Municipal sewage was screened for DNA encoding Shiga-like Toxin (SLT) II, a key protein involved in the virulence of enterohemorrhagic Escherichia coli. PCR analysis of sewage concentrates showed that DNA encoding SLT II was present in a single sample of untreated sewage and absent in all other samples tested (n = 6). Thermotolerant E. coli cultured from the sewage (n = 1,520) also tested negative for SLT II by colony hybridization.

Evaluation of PCR, nested PCR, and fluorescent antibodies for detection of Giardia and Cryptosporidium species in wastewater

Giardiasis and cryptosporidiosis are diseases caused by the protozoan parasites Giardia lamblia and Cryptosporidium parvum. Waterborne transmission of these organisms has become more prevalent in recent years, and regulatory agencies are urging that source and finished water be screened for these organisms. A major problem associated with testing for these organisms is the lack of reliable methodologies and baseline information on the prevalence of these parasites in various water sources. Our study addressed both of these issues. We evaluated the presence and reduction of Giardia cysts and Cryptosporidium oocysts in sewage effluent by a combination of indirect fluorescent antibody (IFA) staining and PCR. Our results indicated a 3-log reduction of Giardia cysts and a 2-log reduction of Cryptosporidium oocysts through the sewage treatment process as determined by IFA. We developed a nested PCR to detect Cryptosporidium oocysts and used a double PCR to detect Giardia cysts. A 100% correlation was noted between IFA and PCR detection of Giardia cysts while correlation for Cryptosporidium oocysts was slightly less. On the basis of these results, PCR may be a useful tool in the environmental analysis of water samples for Giardia and Cryptosporidium organisms.

Comparison of PCR-generated fragments of the mce gene from Mycobacterium tuberculosis, M. avium, M. intracellulare, and M. scrofulaceum

Nineteen strains representing 13 species of mycobacteria were tested for the ability to serve as PCR templates for the production of a 293-bp fragment of the mycobacterial mce gene. The mce gene is a virulence factor recently sequenced from Mycobacterium tuberculosis. PCR products were obtained for only the species of the Mycobacterium tuberculosis complex (MTC) and the Mycobacterium avium-M. intracellulare-M. scrofulaceum complex. The fragment was sequenced from M. tuberculosis (one strain), M. avium (three strains), M. intracellulare (two strains), and M. scrofulaceum (two strains). Sequence comparisons suggest that the fragments from each of the species are regions that code for a similar product. One of the M. scrofulaceum strains yielded a sequence whose most probable reading frame was truncated by an amber stop codon caused by a single nuclei acid difference from the other sequences. The amino acid sequences from the non-MTC sequences cluster together, displaying fewer differences from each other than from the M. tuberculosis sequence and the truncated M. scrofulaceum sequence. Principal component analysis of the distance matrix displays the clustering of the M. avium and M. intracellulare sequences into single-species clusters. It is concluded that at least one open reading frame of the mce gene is found, although it is discernibly different, in pathogenic mycobacteria other than the MTC.

Analysis of sewage effluent for human immunodeficiency virus (HIV) using infectivity assay and reverse transcriptase polymerase chain reaction

Environmental survival of human immunodeficiency virus type 1 (HIV-1) is an important public health concern. Survival of HIV in waste water is of particular interest to those who work at treatment facilities and to the general public who have contact with rivers or ocean water receiving treated sewage effluent. Other researchers have reported that HIV can be detected in waste water. Their studies, however, detected homologous nucleic acid sequences but did not attempt to determine infectivity. The current study tested primary and secondary effluent from a major metropolitan sewage agency for the presence of HIV-1 using reverse transcriptase polymerase chain reaction (RT-PCR), HIV-1 p24 antigen enzyme-linked immunosorbent assay, and infectivity testing. For RT-PCR, primers SK38/SK39 and M667/AA55 were used to identify HIV-1 RNA sequences from concentrated and extracted sewage samples. Infectivity assays employed donor peripheral blood mononuclear cells (PBMCs) stimulated with phytohemagglutinin. Coxsackievirus B4, echovirus 7, and poliovirus 1, enteroviruses normally present in sewage, were tested for replication in PBMCs. Poliovirus 1 was found to infect the PBMCs. To eliminate other enteroviruses that may also infect the PBMCs and interfere with HIV-1 testing, concentrated sewage was treated with human immunoglobulin (free of HIV antibodies) and poliovirus antisera before infectivity assays were performed. All treated sewage samples tested negative for HIV-1 by all methods used. HIV-1 seeded into sewage, however, remained infectious in the assay, indicating that the sewage water sample did not interfere with HIV infectivity nor was it toxic to the PBMCs.

Detection of Legionella species in reclaimed water and air with the EnviroAmp Legionella PCR kit and direct fluorescent antibody staining

Reclaimed water is an important resource for areas with inadequate water supplies. However, there have been few studies on the variety of microorganisms found in this type of water, since typically reclaimed water is examined only for the presence of coliform bacteria. Many microorganisms, including the legionellae, are known to be more resistant to chlorine than are coliform bacteria. Previously, we detected > 10(3) Legionella cells per ml in primary and secondary sewage effluents and observed no significant reduction in population numbers throughout the treatment process. In this study, we detected Legionella spp. in chlorinated effluent by using an EnviroAmp Legionella PCR kit and direct fluorescent antibody (DFA) staining. However, we were not able to isolate Legionella spp. from either natural or seeded reclaimed water samples. This suggests that the Legionella spp. detected by the PCR and DFA methods may be injured or viable but nonculturable after exposure to the high residual chlorine levels typically found in this type of water source. The numbers of coliform bacteria were low (< 2 cells per 100 ml) in most reclaimed water samples and were not correlated with the presence or absence of Legionella spp. We also collected air samples from above a secondary aeration basin and analyzed them by using the PCR, DFA, and plate culture methods. Legionella spp. were detected in the air obtained from above the secondary basin with all three methods. We concluded that the PCR was superior to the culture and DFA methods for detecting Legionella spp. in environmental water samples.

Analysis of viral RNA persistence in seawater by reverse transcriptase-PCR

It is important to determine the stability of naked viral RNA in seawater, since false-positive results can occur when reverse transcriptase-PCR (RT-PCR) is used to detect viruses if the RT-PCR amplifies free RNA instead of RNA from intact viruses. An acid guanidinium thiocyanate-phenol-chloroform method was used to extract total RNA from a filtered poliovirus cell culture suspension. The sensitivity of detection in this viral RNA study was 600 fg when RT-PCR was used. The extracted total RNA was seeded into filtered and unfiltered seawater, and the resulting preparations were incubated at 4 degrees C and at room temperature (23 +/- 1 degrees C). Our results showed that the seeded RNA was more stable in filtered seawater than in unfiltered seawater at both temperatures. The viral RNA could not be detected by the RT-PCR after 2 days of incubation in unfiltered seawater and after 28 days of incubation in filter-sterilized seawater. Therefore, because of the relatively short life of viral RNA in natural water, the detection of virus in environmental samples by the RT-PCR was mainly due to the presence of well-protected viral particles and not due to the presence of naked viral RNA.

Multiplex PCR for detection of the heat-labile toxin gene and shiga-like toxin I and II genes in Escherichia coli isolated from natural waters

A triplex PCR method was developed to simultaneously amplify a heat-labile toxin sequence (LT) of 258 bp, a shiga-like toxin I sequence (SLT I) of 130 bp, and a shiga-like toxin II sequence (SLT II) of 346 bp from toxigenic strains of Escherichia coli. This method was used to screen 377 environmental E. coli isolates from marine waters or estuaries located in Southern California and North Carolina for enterotoxigenic or enterohemorrhagic E. coli strains. Of the 377 E. coli screened, one isolate was found to belong to the enterotoxigenic group, since it contained a LT homologous sequence, and one isolate was found to belong to the enterohemorrhagic group, since it contained a SLT I homologous sequence. None was found to contain SLT II homologous sequences. The pathogenicity of the positive environmental E. coli isolates was confirmed by standard bioassays with Y-1 adrenal cells and Vero cells to confirm toxin production. Our results suggest that toxigenic E. coli occurs infrequently in environmental waters and that there is a low public health risk from toxigenic E. coli in coastal waters.

Detection of poliovirus, hepatitis A virus, and rotavirus from sewage and ocean water by triplex reverse transcriptase PCR

A triplex reverse transcriptase PCR (RT-PCR) was developed to simultaneously detect poliovirus, hepatitis A virus (HAV), and rotavirus in sewage and ocean water. Sewage and ocean water samples seeded with the three different viruses were concentrated by ultrafiltration. The unseeded ocean water and sewage samples were concentrated by vortex flow filtration and/or ultrafiltration. Random hexamers and a rotavirus downstream primer were used to initiate reverse transcription. Three different sets of primers specific for poliovirus, HAV, and rotavirus cDNAs were mixed in the PCR mixture to amplify the target DNA. Three distinct amplified DNA products representing poliovirus, HAV, and rotavirus were identified by gel electrophoresis as 394-, 192-, and 278-bp sequences, respectively. Dot blot and Southern analyses were used to confirm the amplified products for each virus present in the environmental samples. Except for poliovirus, the sensitivity of triplex RT-PCR for the detection of rotavirus and HAV was found to be similar to that of monoplex RT-PCR, which uses only one set of primers to amplify a single type of virus. The triplex RT-PCR has greater advantages over monoplex RT-PCR for virus detection, namely, the rapid turnaround time and cost effectiveness.

Detection of Legionella species in sewage and ocean water by polymerase chain reaction, direct fluorescent-antibody, and plate culture methods

Legionella spp. are ubiquitous in most environmental water sources; however, sewage treatment plants have not been examined as potential environmental reservoirs for these bacteria. This study used polymerase chain reaction, direct fluorescent-antibody staining, and culture methods to examine raw and treated sewage, ocean-receiving waters, and nearshore coastal environments for the presence of Legionella pneumophila and other Legionella spp. The study concluded that Legionella spp. are present in all phases of sewage treatment and that population numbers do not significantly decline through the treatment process. Ocean-receiving waters located 5 miles offshore, where the treated sewage is discharged, were found to contain Legionella spp., but ocean water between the discharge site and coastal bathing beaches was negative. This suggests that the Legionella spp. from the ocean discharge site were not reaching the nearshore beach waters. A flood control channel and river that entered the ocean were found to contain Legionella spp., and a nearby beach swimming area was also found to be positive, suggesting that land runoff from the flood control channel and river were the source of the Legionella spp. in the beach water samples that tested positive.

Simple method of concentrating enteroviruses and hepatitis A virus from sewage and ocean water for rapid detection by reverse transcriptase-polymerase chain reaction

A rapid and simple method was developed to detect enteroviruses and hepatitis A virus (HAV) in sewage and ocean water. Sewage samples were concentrated by Centriprep-100 and Centricon-100 at 1,000 x g. Samples collected from estuary and near-shore surf zone ocean water in Southern California were concentrated by vortex flow filtration and microconcentration. Reverse transcriptase-polymerase chain reaction (RT-PCR), with enterovirus primers or HAV capsid-specific primers, was used to detect enteroviruses or HAV in all concentrated samples. A nonradioactive internal probe was used to confirm the amplified products. Results of seeding experiments indicated that at 4 degrees C, HAV was more persistent than poliovirus in seawater and both HAV and poliovirus persisted longer at 4 degrees C than at 25 degrees C. RT-PCR was at least 500-fold more sensitive than cell culture. Results were obtained within 5 h by RT-PCR, in contrast with the 5 days to 3 weeks required for cell culture.

Evaluation of colilert-marine water for detection of total coliforms and Escherichia coli in the marine environment

A test that allows for early detection of fecally contaminated coastal water would enhance public health protection. Colilert-Marine Water (Colilert-MW; Environetics, Branford, Conn.) is a rapid 24-h test that has recently been developed to detect total coliforms and Escherichia coli in coastal water. We performed a premarketing evaluation of the Colilert-MW product, testing it in parallel with the multiple tube fermentation (MTF) method for 86 coastal water samples in southern California. Statistical analysis was performed by using paired t tests and linear regression. Bacterial isolates were evaluated by biochemical and genetic analysis. The results of this study showed a strong correlation between the traditional MTF and the Colilert-MW method for detection of total coliforms (r = 0.95) and E. coli (r = 0.89) in ocean water samples. Paired t-test results indicated that the Colilert-MW and MTF were equivalent in detecting E. coli and that the Colilert-MW may be more sensitive in the detection of total coliforms. We conclude that Colilert-MW would be a useful tool with which to monitor coastal beach water.

Detection of Escherichia coli in sewage and sludge by polymerase chain reaction

A method in which the polymerase chain reaction (PCR) was used was developed to amplify either a uidA gene fragment or a 16S rRNA gene fragment from Escherichia coli in sewage and sludge. Because of interference caused by humic acidlike substances, crude DNA extracts were purified with a Sephadex G-200 spun column before the PCR was begun. A Southern analysis in which a nonradioactive chemiluminescent method was used was performed to confirm the presence of PCR products. The sensitivity of detection for PCR products when the chemiluminescent method was used was determined to be 30 ag of E. coli genomic DNA template. In seeded sludge, the PCR amplified the target DNA from 80 E. coli cells per g of sludge and 50 Shigella dysenteriae cells per g of sludge. Because only 0.05 aliquot of a sludge extract was used for the PCR, we deduced that the PCR detected target DNA equivalent to the DNA of 2.5 to 4 cells in the extract. The PCR amplified the uidA fragment from diluted sewage influents and effluents containing E. coli cells. Therefore, the PCR performed with a chemiluminescent gene probe can be used to detect the presence of potentially pathogenic microorganisms in sewage and sludge. This technique can be expanded to permit direct detection of pathogenic microorganisms in water samples, thus leading to enhanced public health protection.

Phospholemman expression induces a hyperpolarization-activated chloride current in Xenopus oocytes

A new type of chloride channel has been identified by functional expression of phospholemman, a 72-amino acid cardiac sarcolemmal protein with a single transmembrane domain. Xenopus oocytes injected with phospholemman RNA developed a chloride-selective current, which was activated by hyperpolarizing pulses. The current activated very slowly with a pronounced sigmoidal delay, did not inactivate, and increased in amplitude with trains of pulses, depolarized holding potentials, and low extracellular pH. Point mutations within the single transmembrane region abolished the sigmoidal delay of expressed currents. Phospholemman appears to be the smallest plasma membrane channel protein yet known. The structure is dissimilar to any chloride channel described thus far.

A selection of forest condition indicators for monitoring

Regional monitoring and assessments of the health of forested ecosystems require indicators of forest conditions and environmental stresses. Indicator selections depend on objectives and the strategy for data collection and analysis. This paper recommends a set of indicators to signal changes in forest ecosystem distribution, productivity, and disturbance. Additional measurements are recommended to help ascribe those changes to climate variation, atmospheric deposition, and land use patterns. The rationale for these indicators is discussed in the context of a sequential monitoring and assessment strategy.

Purification and complete sequence determination of the major plasma membrane substrate for cAMP-dependent protein kinase and protein kinase C in myocardium

A protein of apparent Mr = 15,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis is the major plasma membrane substrate for cAMP-dependent protein kinase (PK-A) and protein kinase C (PK-C) in several different tissues. In the work described here, we purified, cloned, and sequenced the canine cardiac sarcolemmal "15-kDa protein." The amino terminus of the purified protein was not blocked, allowing determination of 50 consecutive residues by standard Edman degradation. Overlapping proteolytic phosphopeptides yielded 22 additional residues at the carboxyl terminus. Dideoxy sequencing of the full-length cDNA confirmed that the 15-kDa protein contains 72 amino acids, plus a 20-residue signal sequence. The mature protein has a calculated Mr = 8409. There is one hydrophobic membrane-spanning segment composed of residues 18-37. The acidic amino-terminal end (residues 1-17) of the protein is oriented extracellularly, whereas the basic carboxyl-terminal end (residues 38-72) projects into the cytoplasm. The positively charged carboxyl terminus contains the phosphorylation sites for PK-A and PK-C. In the transmembrane region, the 15-kDa protein exhibits 52% amino acid identity with the "gamma" subunit of Na,K-ATPase. High stringency Northern blot analysis revealed that 15-kDa mRNA is present in heart, skeletal muscle, smooth muscle, and liver but absent from brain and kidney. We propose the name "phospholemman" for the 15-kDa protein, which denotes the protein's location within the plasma membrane and its characteristic multisite phosphorylation.

Photoaffinity ligands for the [3H]TBOB binding site of the GABAA receptor

Two types of 1-substituted-4-t-butyl-2,6,7-trioxabicyclo[2.2.2]octanes are examined as candidate photoaffinity ligands to irreversibly inhibit the [3H]TBOB binding site of the GABAA receptor complex present in bovine brain membranes. The 1-substituted-(4-bromo-6-diazocyclohexa -1,4-dien-3-onyl) derivative (IC50 1.1 microM) dissociates completely in the dark, but on irradiation produces over 40% photoirreversible inhibition of [3H]TBOB binding. This photoinactivation can be partially (64%) protected using a potent and completely dissociating TBOB analog. The 1-substituted-(4-azidophenyl) derivative (IC50 149 nM) also dissociates completely in the dark and at 2.2 microM gives 20% photoirreversible inhibition which is completely protectable. The corresponding 1-(4-azido-3,5-dichlorophenyl) analog and its 4-(1-methylpropyl) isomer are 16- and 8-fold more potent inhibitors, respectively, than the azidophenyl derivative but these dichloro probes are not examined further because they do not dissociate in the dark by an apparently non-covalent mechanism. Thus, the bromodiazocyclohexadienonyl and azidophenyl compounds photoirreversibly and therefore covalently modify the [3H]TBOB binding site of the GABAA receptor complex.

Inhibition of offspring response to HEL-CFA by administration of anti-HEL MAB to the mother is not related to the predominant idiotype, IdXE, or specificity of the MAB

In the neonatal suckling mouse, the antibody response to HEL-CFA can be inhibited by administration of certain anti-HEL monoclonal antibodies to the mother. The murine primary response to hen egg-white lysozyme (HEL), which can be elicited in A/J mice as early as 7 days of age, is characterized by a predominant specificity that includes the 3 N-terminal amino acids of HEL (TIP-dependence) and by a predominant idiotype, IdXE. A panel of murine IgG1 anti-HEL mAbs was administered to the suckling offspring via the mother. These mAbs were not equivalent in their effects on the offspring. Only two of six IgG1 mAbs, 2F4/2E5 (IdXE-positive, TIP-dependent) and 2D1 (IdXE-negative, TIP-independent), consistently induced suppression of the response of A/J offspring when immunized at 16-20 days of age with HEL-CFA. Suppression averaged 71% for 2F4/2E5 and 74% for 2D1 and was always statistically significant (P less than .05) when 275 micrograms mAb was administered IP to the mother within 24 hr postpartum. Since 2D1 is IdXE-negative and TIP-independent, neither of these properties appears to be crucial for suppression. Differences in transfer of the mAbs from the mother to the offspring or differences in catabolism of the mAbs in the offspring were not detected. When various characteristics of the mAbs such as affinity, idiotypy, and fine specificity were considered, there was no single factor which determined suppression. One of the two mAbs that suppressed the offspring response, 2D1, is idiotypically highly connected in the anti-HEL mAb panel. This observation suggests that idiotypic interactions in the developing neonatal repertoire with subsequent perturbation of T and B cell repertoire development may be an area for future investigation.

Two types of cage convulsant action at the GABA-gated chloride channel

Cage convulsants appear to fall into two groups based on correlations between their potency for inhibiting [35S]t-butylbicyclophosphorothionate binding or gamma-aminobutyric acid-stimulated 36chloride uptake in brain membrane preparations and their toxicity to mice. Polychlorocycloalkanes, picrotoxinin and 2,6,7-trioxabicyclo[2.2.2]octanes with large 1-substituents exhibit high potency in these in vitro brain membrane systems relative to their toxicity (type A action). In contrast, trioxabicyclooctanes with small 1-substituents and tetramethylenedisulfotetramine show much lower in vitro potency relative to their toxicity (type B action). Compounds with type A action are generally more potent insecticides than those with type b action.

Modulation of gamma-aminobutyric acid-stimulated chloride influx by bicycloorthocarboxylates, bicyclophosphorus esters, polychlorocycloalkanes and other cage convulsants

gamma-Aminobutyric acid (GABA) stimulated 36Cl- influx into membrane vesicles from rat cerebral cortex at 3 to 300 microM in a concentration-dependent manner with near maximum response at 100 microM. Inhibitory potencies for this GABA (100 microM)-dependent 36Cl- uptake were determined for 16 cage convulsants including 10 bicycloorthocarboxylates and 3 bicyclophosphorus esters and for 8 polychlorocycloalkane insecticides. Inhibition by derivatives of t-butylbicycloorthobenzoate (TBOB) and t-butylbicyclophosphorothionate (TBPS) depended on the substituents at both positions 1 and positions 4. Among them, the 4-cyano-phenyl analog of TBOB was the most potent inhibitor with an IC50 value of 40 nM. Other cage convulsants such as picrotoxinin, tetramethylenedisulfotetramine and p-chlorophenylsilatrane were less potent than TBOB and TBPS. The potencies of bicycloorthocarboxylates, bicyclophosphorus esters and other cage convulsants in inhibiting GABA-stimulated 36Cl- uptake by rat cerebral cortex were significantly correlated with those in inhibiting [35S]TBPS binding to the human and mouse brain receptors (r = 0.96, P less than .01). There also was a significant correlation between the potencies of the polychlorocycloalkanes examined in inhibiting GABA-stimulated 36Cl- uptake and [35S]TBPS binding to the mouse brain receptor (r = 0.94, P less than .01). In these correlations, the polychlorocycloalkanes appear to fall on a different line than that for the bicycloorthocarboxylates, bicyclophosphorus esters and other cage convulsants. Both the cage convulsants and the polychlorocycloalkanes are considered to act at convulsant sites coupled functionally to the GABA receptor chloride ionophore complex and thereby to modulate allosterically or directly the GABA-gated chloride channel leading to their toxic action.

Oxidative metabolism of the GABAA receptor antagonist t-butylbicycloortho[3H]benzoate

1. The trioxabicyclooctane ring of t-butylbicycloortho[3H]benzoate (TBOB), (CH3)3CC(CH2O)3CC6H5, is cleaved to yield the 3-oxo-benzoate, (CH3)3CC(CHO)(CH2OH)CH2OC(O)C6H5, on O-methylene hydroxylation by microsomes from mouse liver or houseflies in the presence of NADPH. 2. The methyl and phenyl substituents are tentatively identified as additional sites of oxidative metabolism. 3. The 3-oxo-benzoate from oxidative cage opening and the bis-(hydroxymethyl)-benzoate, (CH3)3CC(CH2OH)2CH2OC(O)C6H5, from enzymic reduction of the 3-oxo-benzoate undergo esteratic hydrolysis to benzoic acid. 4. Metabolites of TBOB excreted by rats and houseflies include the bis-(hydroxymethyl)-benzoate and benzoic and hippuric acids. 5. Metabolic hydroxylation of TBOB at O-methylene, alkyl and aryl substituents may serve as a model for detoxication reactions of related potent GABAA receptor antagonists and insecticides.

Bicycloorthocarboxylate convulsants. Potent GABAA receptor antagonists

4-t-Butyl-1-(4-bromophenyl)-bicycloorthocarboxylate antagonizes gamma-aminobutyric acid (GABA)-mediated relaxation at a functional insect nerve-muscle synapse, mimicking the action of picrotoxinin, suggesting that it causes GABA antagonism through blockade of the chloride ionophore. It is also a potent GABAA receptor antagonist, inhibiting the binding of [35S]t-butyl-bicyclophosphorothionate ([35S]TBPS) to EDTA/water-dialyzed human brain P2 membranes. Structure-activity relationships of 74 1,4-bis-substituted bicycloorthocarboxylates, mostly new compounds, reveal that for high potency as a GABAA receptor antagonist the optimal 4-substituent is a C4 to C6 branched chain alkyl or cycloalkyl group (e.g., t-butyl, s-butyl, or cyclohexyl) and the optimal 1-substituent is a phenyl moiety with one or more electron-withdrawing groups (e.g., 4-cyano, 4-bromo, 4-chloro, 3,4-dichloro, or pentafluoro). Bicycloorthocarboxylate inhibitors of [35S]TBPS binding with IC50 values of 5-10 nM exceed by several-fold the potency of any GABAA receptor antagonist previously reported. The 4-t-butyl-1-(4-azidophenyl) analog, synthesized as a candidate photoaffinity label, gives an IC50 of 315 nM. The potency of bicycloorthocarboxylates for decreasing [35S]TBPS binding generally correlates with their toxicity, i.e., compounds without inhibitory activity in this brain receptor assay are of low toxicity on intraperitoneal administration to mice, and the analogs most potent as inhibitors are generally those most toxic to mice (e.g., IC50 of 5 nM and LD50 of 0.06 mg/kg for 4-t-butyl-1-(4-cyanophenyl)-bicycloorthocarboxylate). The effects of phenyl substituents on the potency of the orthobenzoates as GABAA receptor antagonists are similar to those on toxicity. In contrast to the 1-substituted phenyl compounds, 4-t-butyl-1-ethynyl-bicycloorthocarboxylate and its 4-i-propyl analog are very toxic (LD50 0.4-2 mg/kg) but have only moderate inhibitory potency (IC50 480-2900 nM), a pattern noted for many 1-alkyl-bicycloorthocarboxylates, suggesting that even within this series there may be different types of receptor-inhibitor interactions. 1-(4-Chlorophenyl)-4-cyclohexyl-bicycloorthocarboxylate is particularly sensitive to oxidative detoxification based on its 10-fold synergism of toxicity by piperonyl butoxide and marked potency loss in a coupled [35S]TBPS receptor/microsomal oxidase assay. Some benzodiazepines and phenobarbital protect against poisoning by 1-(4-bromophenyl)- and 1-ethynyl-4-t-butyl-bicycloorthocarboxylates and their 1-(4-bromophenyl)-4-cyclohexyl analog.(ABSTRACT TRUNCATED AT 400 WORDS)

t-[3H]butylbicycloorthobenzoate: new radioligand probe for the gamma-aminobutyric acid-regulated chloride ionophore

t-[3H]Butylbicycloorthobenzoate [( 3H]TBOB; 22 Ci/mmol) was prepared by reductive dechlorination of its 4-chlorophenyl analog with tritium gas. This new radioligand binds reversibly to fresh washed rat brain P2 membranes in 500 mM NaCl plus 50 mM sodium-potassium phosphate buffer (pH 7.4) at 25 degrees C, with 80-90% specific relative to total binding, a KD of 61 +/- 15 nM, and a Bmax of 1.6 +/- 0.5 pmol/mg of protein. [3H]TBOB association with its binding site(s) is monophasic, but its dissociation is biphasic. The binding characteristics of [3H]TBOB are essentially identical to those of t-[35S]butylbicyclophosphorothionate [( 35S]TBPS) with respect to pH dependence, stimulation by anions, regional distribution in the brain, and pharmacological profile. Saturation analyses and dissociation studies further indicate that TBOB and TBPS have a common binding site. However, binding of the two radioligands differs in respect to temperature effects. In contrast to [35S]TBPS, which exhibits negligible binding at 0 degrees C, [3H]TBOB binds to rat brain membranes at 0, 25, and 37 degrees C with similar KD values. [3H]TBOB with its long radioactive half-life and temperature-independent KD is a valuable supplement to [35S]TBPS in further biochemical and pharmacological characterization of the gamma-aminobutyric acid receptor-ionophore complex.

The diabetic Zucker fatty rat

A noninsulin-dependent diabetes appeared in fatty rats in our Zucker rat colony. A breeding program yielded a genetic pattern of diabetes consistent with a dominant gene not closely linked to the fatty gene. Fatty males were more frequently affected than fatty females. Since no markers could be identified for heterozygous carriers and since affected fatty rats were 6 months old when diabetes appeared, the diabetic trait could not be sustained in our small colony. Glucose tolerance tests showed that the diabetic fatty rats had little increase in plasma insulin concentration after a glucose load was administered. Plasma insulin concentrations were unchanged relative to control fatty rats. Percentage body fat and plasma triglyceride values were decreased in fatty diabetic rats relative to control fatty rats, however, consistent with insulin resistance in fat and liver. The content of pancreatic insulin was markedly decreased in the diabetic fatty rat relative to either the ad libitum or diet-restricted fatty rats. The occurrence of a genetically based diabetes in a normally outbred colony underscores the importance of genetic traits that interact with obesity in determining diabetes in rodent models.