Prevention of thermal and condensation errors in pneumotachographic recordings of the maximal forced expiratory manoeuvre

When recording respiratory manoeuvres using a pneumotachograph (PT), it is customary to heat the pneumotachograph head to avoid condensation errors. It is technically demanding to heat the PT correctly, and this increases the complexity of the equipment. We have studied whether a simpler method can eradicate condensation errors and preserve thermal stability of the PT. We tested the accuracy of a PT by recording the discharge of 1,000 ml of air through the PT before and after a subject had blown through it, thus causing both condensation within the PT and a rise in its temperature. We then determined whether the thermal and condensation errors could be avoided by placing the PT, between blows, on a fan that was blowing air at a constant 1.65 l.s-1. With ambient temperature at 20 degrees C, a single blow through the PT was found to cause a subsequent 4% over-reading in volume, due to condensation and temperature changes in the PT. After five consecutive blows the error was 7%. Placing the PT on the fan for 15 s after a single blow abolished these errors, whereas a wait of 15 s did not. At an ambient temperature of 14 degrees C there was a 5% over-reading of volume after a single blow, and an over-reading of 9% after five blows. At an ambient temperature of 26 degrees C these errors were 3 and 5%, respectively. All of these errors were abolished by placing the PT on the fan for 15 s and 30 s, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of association of human immunodeficiency virus seroconversion with visits to foreign ports in US Navy personnel

BACKGROUND

The US Navy visits ports on all continents and many islands of the world, many of which are reported to have a high endemicity of human immunodeficiency virus (HIV) infection. The objective of this study was to determine whether visits to foreign ports by active-duty navy personnel were associated with increased risk of HIV infection.

METHODS

The Naval Health Research Center in San Diego, Calif, maintains records of all HIV enzyme-linked immunosorbent assay and Western blot tests given in the navy. This information, along with career histories and ship movement data, was used in a nested case-control design to examine the relationship between visits to the 100 foreign ports most frequently visited by the navy and risk of HIV seroconversion. All visits to a port and total time in each port during the study period were examined. A total of 813 seroconverters were matched to 6993 seronegative active-duty controls by age, race, sex, occupational group, home port, and year of test.

RESULTS

Estimated relative risks of seroconversion associated with visits to foreign ports showed no statistically significant excess risk of HIV infection for navy personnel after visits to any foreign port.

CONCLUSIONS

These results do not imply that an individual's risk of acquisition of HIV would be less in a foreign port if the individual engaged in high-risk activity there. Rather, they imply that despite the mobility of the US Navy and the large variation in HIV seroprevalence rates throughout the world, navy personnel generally do not appear to be acquiring HIV infections abroad.

Expired air temperature at the mouth during a maximal forced expiratory manoeuvre

We have studied the temperature of expired air during a maximal forced expiratory manoeuvre, because this has not previously been fully investigated and it will influence how flow and volume recording devices should be calibrated and used. Temperature was recorded with a fine thermocouple, the response time of which was determined at various gas velocities and for which a correction was made. Recordings during maximal forced expiratory manoeuvres were made on 12 normal subjects and 12 subjects with chronic airflow limitation. The thermocouple was placed in the mouthpiece, so that it was at the level of the lips during a blow. In the normal subjects, the effect of differing inhalation protocols was also determined. In the normal subjects, the mean temperature was 33.6 degrees C at peak expiratory flow (PEF), and 34.4 degrees C at 75% forced vital capacity (FVC), but fell to 33.4 degrees C at FVC. In the subjects with chronic airflow limitation, the temperature was constant at 35.0 degrees C from PEF up to 50% FVC, being significantly higher than in the normals, and fell to 33.5 degrees C at FVC. Expired air temperature up to 50% FVC was significantly negatively correlated with absolute PEF, forced expiratory volume in one second (FEV1) and FVC. In the normals, a slow inhalation through the nose raised the expired temperature by almost 1 degree C throughout the blow, whereas inhaling air at 6 degrees C did not affect expired air temperature. The expired air temperature can vary by up to 3 degrees C between individual subjects, and it is influenced by the route of inhalation and the inspired volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Geographic variation in human immunodeficiency virus seroconversion rates in the U.S. Navy

The Navy population is centered around 19 U.S. home ports and several inland duty stations. This is a study of variation in human immunodeficiency virus (HIV) seroconversions in Navy enlisted men by location in the United States, based on 949,570 enzyme-linked immunosorbent assays and 812 seroconversions during 1987-90. Seroconversion rates were higher in personnel in San Francisco (p = 0.0004), Washington, D.C. (p = 0.001), and Orlando, FL (p = 0.04) than in other areas. They were lower in Charleston, SC, New London, CT, Seattle; and Brunswick, ME (p < 0.05). Black men had triple the seroconversion rate of all other men (p < 0.0001). After adjustment for race, age, marital status, and occupation, risk of seroconversion remained high in San Francisco (p = 0.02) and Orlando (p = 0.03). The risk of seroconversion in San Francisco was twice that of other areas in a cohort that did not change location (p = 0.01). In contrast to declining trends overall in the Navy, rates did not decrease in Washington, D.C., a result consistent with previous calculations indicating a delayed second wave of HIV infection in the region.

Expired air temperature at the mouth during a maximal forced expiratory manoeuvre

We have studied the temperature of expired air during a maximal forced expiratory manoeuvre, because this has not previously been fully investigated and it will influence how flow and volume recording devices should be calibrated and used. Temperature was recorded with a fine thermocouple, the response time of which was determined at various gas velocities and for which a correction was made. Recordings during maximal forced expiratory manoeuvres were made on 12 normal subjects and 12 subjects with chronic airflow limitation. The thermocouple was placed in the mouthpiece, so that it was at the level of the lips during a blow. In the normal subjects, the effect of differing inhalation protocols was also determined. In the normal subjects, the mean temperature was 33.6 degrees C at peak expiratory flow (PEF), and 34.4 degrees C at 75% forced vital capacity (FVC), but fell to 33.4 degrees C at FVC. In the subjects with chronic airflow limitation, the temperature was constant at 35.0 degrees C from PEF up to 50% FVC, being significantly higher than in the normals, and fell to 33.5 degrees C at FVC. Expired air temperature up to 50% FVC was significantly negatively correlated with absolute PEF, forced expiratory volume in one second (FEV1) and FVC. In the normals, a slow inhalation through the nose raised the expired temperature by almost 1 degree C throughout the blow, whereas inhaling air at 6 degrees C did not affect expired air temperature. The expired air temperature can vary by up to 3 degrees C between individual subjects, and it is influenced by the route of inhalation and the inspired volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic cellular distribution of cytochrome P-450 IA1 in rainbow trout (Oncorhynchus mykiss): an immunohisto- and cytochemical study

Monoclonal antibody 1-12-3 reactive against scup (Stenotomus chrysops) cytochrome P450 E (a teleost CYP IA1) has been used to immunohistochemically localize CYP IA1 within hepatocytes and presumably sinusoidal endothelial and biliary epithelial cells of scup and trout. The goal of the present study was to extend immunohistochemical studies to the ultrastructural level determining intracellular locations of CYP IA1 in fish liver. Juvenile trout (5-10 g) were given i.p. injections once (50 micrograms/g b beta-naphthoflavone in cod liver oil; 0.5-ml injectate volume). After 5 days, livers were fixed (0.25% glutaraldehyde) via vascular in situ perfusion, removed, cut in 100-microns slices, infiltrated, and embedded in LR White monomer. Ultrathin sections of exposed livers were incubated in monoclonal antibody 1-12-3, rabbit anti-mouse IgG, and protein G colloidal gold. Membranes of granular endoplasmic reticulum in perinuclear regions of hepatocytes were consistently labeled. In addition, hepatocyte plasma membrane, particularly microvilli at bile canaliculi, was labeled. Biliary epithelial cells were labeled on luminal plasma membrane surrounding biliary passageway. Plasma membrane facing sinusoid and immediately subjacent cytoplasm was labeled in endothelial cells. Presence of CYP IA1 in sinusoidal endothelium could contribute to detoxication and/or bioactivation of blood borne chemicals. Granular endoplasmic reticulum was not uniformly labeled in hepatocytes. Rather, distribution seemed sequestered within highly specific regions and not dispersed along all membrane surfaces. Localization within biliary epithelial cells could signify potential of this cell type to bioactivate polycyclic aromatic hydrocarbons and may explain the common finding of biliary as well as hepatocytic tumors of trout liver.

Alterations in the pulmonary microsomal cytochrome P-450 system after exposure of rats to silica

Because some evidence indicates that there is an increased incidence of lung cancer in silicosis, we studied the effects of exposing rats to silica on the pulmonary microsomal cytochrome P-450 system. Rats were exposed to silica by intratracheal administration, lung microsomes were obtained from untreated and silica-treated animals, and the amount of microsomal tissue, the level of total cytochromes P-450 (all isozymes), the activity of NADPH cytochrome P-450 reductase, the metabolism of two xenobiotics, and the relative amounts of cytochrome P-4502B1 and P-4501A1 were measured. Lungs from silica-treated rats were almost 2-fold heavier and contained more than 10 times more alveolar phospholipids than lungs from untreated animals, indicating that acute silicosis had been produced. In lungs from silica-treated animals, the concentration of microsomal tissue, expressed as milligrams of microsomal protein per gram of lung, was increased by more than 2-fold, and total microsomal protein content was increased by almost 5-fold relative to untreated animals. When expressed as activity or amount per milligram of protein, the microsomal concentrations of NADPH cytochrome P-450 reductase, total cytochromes P-450, 7-ethoxycoumarin (EC)-0-deethylase, and cytochrome P-4502B1 are reduced by approximately 50% in silica-treated rats. However, when expressed as total activity or amount in the lungs, all are increased by approximately 1.5- to 2.5-fold in silica-treated lungs. On the other hand, total lung 7-ethoxyresorufin (ER)-0-deethylase activity and cytochrome P-4501A1 are increased by 4- to 5-fold in silica-treated lungs.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of an accurate portable recording peak-flow meter for the diagnosis of asthma

This article describes the systematic design of an electronic recording peak expiratory flow (PEF) meter to provide accurate data for the diagnosis of occupational asthma. Traditional diagnosis of asthma relies on accurate data of PEF tests performed by the patients in their own homes and places of work. Unfortunately there are high error rates in data produced and recorded by the patient, most of these are transcription errors and some patients falsify their records. The PEF measurement itself is not effort independent, the data produced depending on the way in which the patient performs the test. Patients are taught how to perform the test giving maximal effort to the expiration being measured. If the measurement is performed incorrectly then errors will occur. Accurate data can be produced if an electronically recording PEF instrument is developed, thus freeing the patient from the task of recording the test data. It should also be capable of determining whether the PEF measurement has been correctly performed. A requirement specification for a recording PEF meter was produced. A commercially available electronic PEF meter was modified to provide the functions required for accurate serial recording of the measurements produced by the patients. This is now being used in three hospitals in the West Midlands for investigations into the diagnosis of occupational asthma. In investigating current methods of measuring PEF and other pulmonary quantities a greater understanding was obtained of the limitations of current methods of measurement, and quantities being measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaminophen toxicity in cultured trout liver cells. I. Morphological alterations and effects on cytochrome P450 1A1

To better characterize the hepatotoxicity of acetaminophen, the effects of this drug were investigated on isolated liver cells from a species relatively resistant to acetaminophen toxicity, rainbow trout. At high concentrations of acetaminophen (2-10 mM), pathologic effects were detected, including loss of lactate dehydrogenase from cells, disruption of cell-cell aggregation, cell death, and distinctive alterations in cell morphology, as demonstrated by light and electron microscopic examination. Most striking was the acetaminophen-induced rearrangement of mitochondria, which were clustered adjacent to the nucleus and rarely seen at cell periphery. The endoplasmic reticulum was also altered by acetaminophen treatment. In the middle portion of the cytoplasm, parallel arrays of endoplasmic reticulum cisternae were abundant; however, the peripheral cytoplasm was restricted to vesicular profiles of endoplasmic reticulum. Although nuclei in acetaminophen-treated cells displayed peripheral heterochromatin aggregation, acetaminophen did not produce detectable DNA fragmentation, in contrast to effects reported for mouse liver cells. Thus DNA fragmentation does not appear to be required for acetaminophen to manifest cytotoxic effects. In addition, immunohistochemical studies indicated that toxic concentrations of acetaminophen which altered the endoplasmic reticulum helped maintain cytochrome P450 1A1 in liver cells from beta-naphthoflavone-induced trout.

Acetaminophen toxicity in cultured trout liver cells. II. Maintenance of cytochrome P450 1A1

Acetaminophen was demonstrated to maintain cytochrome P450 1A1 (P450 1A1) in isolated rainbow trout liver cells cultured in serum-free medium. This novel finding was characterized in detail. Cultured trout liver cells retained their ability to respond to typical 1A1 inducers in vitro; induction of ethoxyresorufin O-deethylase (EROD) activity was readily demonstrated by exposing liver cells from control trout to beta-naphthoflavone (BNF), Aroclor 1254, or 7,12-dimethylbenz[a]anthracene. BNF was the most potent inducer studied and was used in further experiments. High levels of EROD activity, immunoreactive 1A1, and 1A1 mRNA were expressed in liver cells prepared from trout pretreated with BNF. However, all of these 1A1-specific indicators rapidly declined when cells from BNF-treated trout were placed in culture, and BNF in culture medium was not effective in maintaining EROD activity. Immunohistochemical studies suggested that addition of acetaminophen to liver cells prepared from BNF-induced trout helped maintain elevated levels of P450 1A1. Total cytochrome P450, EROD activity and immunoreactive P450 1A1 were retained in liver cells from BNF-induced trout by the addition of acetaminophen, in a dose-dependent manner. The concentrations of acetaminophen most effective in maintaining P450 1A1 produced cytotoxic effects, including vesiculation of endoplasmic reticulum. Furthermore, the acetaminophen maintenance of P450 1A1 was primarily attributed to elevated levels of P450 1A1 mRNA. In contrast to BNF, acetaminophen was not capable of inducing 1A1 in liver cells prepared from control trout. This is the first report to demonstrate that acetaminophen can help maintain P450 1A1 and that this effect is exerted at the level of P450 1A1 mRNA.

A multistate outbreak of Salmonella javiana and Salmonella oranienburg infections due to consumption of contaminated cheese

OBJECTIVE

To determine the source of an outbreak of Salmonella javiana and Salmonella oranienburg infections.

DESIGN

Laboratory-based statewide surveillance for Salmonella infections and two separate case-control studies.

SETTING

Community- and industry-based studies conducted from May through October 1989.

PARTICIPANTS

Thirty-one culture-confirmed outbreak-associated cases of S javiana infection and 60 community controls matched for telephone prefix, gender, and age in case-control study I; 50 cases, 100 community controls, and 64 family member controls in case-control study II.

RESULTS

One hundred thirty-six culture-confirmed cases of S javiana infection and 11 cases of S oranienburg infection were associated with the outbreak in Minnesota. Outbreak-associated cases were also identified in Wisconsin (15 cases), and in Michigan and New York (one case each). Cases were more likely than controls to have consumed mozzarella cheese manufactured at a single cheese plant (plant X) or cheese that had been shredded at processing plants that also shredded cheese manufactured at plant X (odds ratio [OR], 7.2; 95% confidence interval [CI], 1.7 to 23.2; P < .01). The outbreak-associated strains of both serovars were isolated from two unopened 16-oz (0.45-kg) blocks of mozzarella cheese produced at plant X. The most probable numbers of Salmonella organisms in these samples were 0.36/100 g and 4.3/100 g.

CONCLUSIONS

The potential for bacterial pathogen contamination of cheese during manufacture and processing has important epidemiologic implications, particularly because cheese consumption has recently increased in the United States. Low-level contamination of a nationally distributed food product can cause geographically dispersed foodborne outbreaks that may be difficult to detect.

The accuracy of portable peak flow meters

BACKGROUND

The variability of peak expiratory flow (PEF) is now commonly used in the diagnosis and management of asthma. It is essential for PEF meters to have a linear response in order to obtain an unbiased measurement of PEF variability. As the accuracy and linearity of portable PEF meters have not been rigorously tested in recent years this aspect of their performance has been investigated.

METHODS

The response of several portable PEF meters was tested with absolute standards of flow generated by a computer driven, servo controlled pump and their response was compared with that of a pneumotachograph.

RESULTS

For each device tested the readings were highly repeatable to within the limits of accuracy with which the pointer position can be assessed by eye. The between instrument variation in reading for six identical devices expressed as a 95% confidence limit was, on average across the range of flows, +/- 8.5 l/min for the Mini-Wright, +/- 7.9 l/min for the Vitalograph, and +/- 6.4 l/min for the Ferraris. PEF meters based on the Wright meter all had similar error profiles with overreading of up to 80 l/min in the mid flow range from 300 to 500 l/min. This overreading was greatest for the Mini-Wright and Ferraris devices, and less so for the original Wright and Vitalograph meters. A Micro-Medical Turbine meter was accurate up to 400 l/min and then began to underread by up to 60 l/min at 720 l/min. For the low range devices the Vitalograph device was accurate to within 10 l/min up to 200 l/min, with the Mini-Wright overreading by up to 30 l/min above 150 l/min.

CONCLUSION

Although the Mini-Wright, Ferraris, and Vitalograph meters gave remarkably repeatable results their error profiles for the full range meters will lead to important errors in recording PEF variability. This may lead to incorrect diagnosis and bias in implementing strategies of asthma treatment based on PEF measurement.

Decline in human immunodeficiency virus seropositivity and seroconversion in US Navy enlisted personnel: 1986 to 1989. Navy HIV Working Group

The US Navy administered 1,795,578 enzyme-linked immunosorbent assay (ELISA) tests to 848,632 active-duty Navy enlisted personnel during 1986 to 1989. This study identified 2438 human immunodeficiency virus (HIV)-seropositive active-duty enlisted Navy personnel, including 778 seroconverters. Three types of quarterly rates of HIV seropositivity and seroconversion were determined. All three rates declined. This decline could not be explained by changes in the population tested according to age, race, sex, occupation, or geographic location of home port.

Nutrition education in supermarkets: the Lifestyle 2000 experience

A 15-week supermarket-based nutrition education program was conducted as part of a larger multiple-strategy community-wide health promotion project. The program consisted of point-of-purchase materials displayed in the supermarkets and was supported by a mass media campaign and promotional activities such as competitions, taste testing and cooking demonstrations. The objective of the program was to promote the selection and purchase of low-fat foods, specifically low-fat dairy products, fresh fruit and vegetables, bread and cereal products. Awareness of the promotion was high, with some self-reported behaviour change. Supermarkets are potential sites for public health nutrition education and recommendations are made for improving the effectiveness of point-of-purchase promotions.

Valproate use in the older manic patient

The authors present a case series of seven older (mean age = 66 years) state hospital patients treated with valproate as an adjunct to conventional medications. The patients had had affective disorder (chiefly bipolar disorder) for an average of 31 years. Most had been hospitalized at the state hospital for several years. Previous unsuccessful treatments had included lithium, carbamazepine, antipsychotics, benzodiazepines, and antidepressants and electroconvulsive therapy in one patient. After 1 month of adjunctive treatment, valproate led to marked improvement in three patients, moderate improvement in two, minimal improvement in one, and no change in one patient with delusional depression. Global Assessment Scale scores increased over baseline an average of 29 points (p = .01). Valproate proved to be safe in these older individuals, many of whom had several medical conditions.

Further serial transmission electron microscopy studies of auditory hair cell innervation in lizards and in a snake

Auditory hair cells of three lizard and one snake species were studied by serial transmission electron microscopy (TEM) sections of two unidirectional hair cells (UHC) and two bidirectional hair cells (BHC) and by nonserial section montages of each entire papilla cut at 2-microns intervals across the papillar width. The unidirectional hair cell region of the agamid lizard, Acanthosaura crucigera, lacked efferent innervation. Another agamid lizard, Agama agama, studied by nonserial section only, also lacked efferent innervation to the UHC. Afferent innervation to both the UHC and BHC of Acanthosaura was primarily exclusive (each nerve fiber innervates only one hair cell), although an occasional nerve fiber innervated two hair cells. Both the UHC and the BHC of the anguid, Celestus costatus, were exclusively innervated. Both hair cell types of the varanid, Varanus exanthematicus, were nonexclusively innervated (all afferent nerve fibers innervate two or more hair cells). The auditory papilla of the colubrid snake, Elaphe obsoleta, has only one type of hair cell and each is nonexclusively innervated. The numbers of afferent and efferent nerve fibers and of afferent synapses are presented in tabular form.

Isolated trout liver cells: establishing short-term primary cultures exhibiting cell-to-cell interactions

Composition and interactions of cell types in rainbow trout (Oncorhynchus mykiss) liver digested with collagenase and cultured in serum-free media were investigated. Suspensions obtained after digesting trout liver with collagenase contained all the cell types present in the liver, including liver parenchymal cells (hepatocytes), biliary epithelial cells, sinusoidal endothelium, fat-storing cells of Ito, and macrophages. A major cell pellet, mainly hepatocytes but containing significant numbers of biliary epithelial cells, was obtained by centrifuging the cell suspension at 120 X g for 1 min. Cells present in this pellet quantitatively attached to culture plates coated with a trout skin extract and remain attached for 4 to 6 d with good retention of intracellular enzymes and DNA. When in culture, significant changes in and among the cells were observed. Initial preparations were rounded, single cells. Within several hours, however, cellular interactions leading to aggregation became evident and aggregates increased in size for 2 to 3 d. Scanning electron microscopy (EM) showed frequent shaftlike projections from margins of the aggregates. Transmission EM indicated that these projections represent biliary ductules forming in vitro. Adjacent hepatocytes also showed plasma membrane specializations forming junctional complexes and canaliculi characteristics of normal trout liver. After 5 to 6 d in culture, significant numbers of the cell aggregates dislodged from the plate. Analysis showed the dislodged cells were viable but vacuolated. The reestablishment in vitro of morphologic relationships resembling in situ tissue components suggest these culture preparations may have significant utility in cooperative metabolic studies of cell interactions in trout liver.

Upper airway obstruction due to goitre: detection, prevalence and results of surgical management

A group of 132 women and 12 men with goitre were studied to determine the prevalence of upper airway obstruction caused by the goitre. Inspection of flow-volume loops was used to detect upper airway obstruction and this suggested that 44 subjects (31 per cent) had the condition. Of these 44 subjects 19 per cent were men, which was a greater proportion than could be accounted for by chance. Flow-volume loops after surgery were recorded on 43 patients of whom 29 were from the group thought to have had upper airway obstruction. Comparison of measurements before and after surgery showed no important change in the 14 without, and improvement in 27 of those with, upper airway obstruction. Analysis indicated two failures of treatment and four probable false-positives among the group with upper airway obstruction. Inspection of the flow-volume loop had a 78 per cent specificity and 100 per cent sensitivity in detecting upper airway obstruction whereas an FEV:PEF ratio above 8 had a specificity of 94 per cent and a sensitivity of 64 per cent in this respect. Ultrasonography and plain radiography of the upper airway accurately predicted retrosternal extension of the goitre but did not predict upper airway obstruction. It is recommended that all patients with symptomatic goitre should have a flow volume loop recorded.

Effect of DNA polymerase inhibitors on DNA repair in intact and permeable human fibroblasts: evidence that DNA polymerases delta and beta are involved in DNA repair synthesis induced by N-methyl-N'-nitro-N-nitrosoguanidine

The involvement of DNA polymerases alpha, beta, and delta in DNA repair synthesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was investigated in human fibroblasts (HF). The effects of anti-(DNA polymerase alpha) monoclonal antibody, (p-n-butylphenyl)deoxyguanosine triphosphate (BuPdGTP), dideoxythymidine triphosphate (ddTTP), and aphidicolin on MNNG-induced DNA repair synthesis were investigated to dissect the roles of the different DNA polymerases. A subcellular system (permeable cells), in which DNA repair synthesis and DNA replication were differentiated by CsCl gradient centrifugation of BrdUMP density-labeled DNA, was used to examine the effects of the polymerase inhibitors. Another approach investigated the effects of several of these inhibitors on MNNG-induced DNA repair synthesis in intact cells by measuring the amount of [3H]thymidine incorporated into repaired DNA as determined by autoradiography and quantitation with an automated video image analysis system. In permeable cells, MNNG-induced DNA repair synthesis was inhibited 56% by 50 micrograms of aphidicolin/mL, 6% by 10 microM BuPdGTP, 13% by anti-(DNA polymerase alpha) monoclonal antibodies, and 29% by ddTTP. In intact cells, MNNG-induced DNA repair synthesis was inhibited 57% by 50 micrograms of aphidicolin/mL and was not significantly inhibited by microinjecting anti-(DNA polymerase alpha) antibodies into HF nuclei. These results indicate that both DNA polymerases delta and beta are involved in repairing DNA damage caused by MNNG.

Incidence of human immunodeficiency virus seroconversion in US Navy and Marine Corps personnel, 1986 through 1988

From 1986 through 1988, the US Navy and US Marine Corps administered 1,956,631 enzyme-linked immunosorbent assay screening tests for antibodies to the human immunodeficiency virus to 1,070,511 active-duty enlisted and officer personnel. This study identified all persons who had an initial test with negative results. This population was then followed up and those who later tested positive for human immunodeficiency virus were identified as seroconverters. There were 582 seroconversions identified from a total of 987,479 person-years at risk. The age adjusted seroconversion rate and 95% Poisson confidence intervals for navy personnel was 0.69 per 1000 person-years (95% confidence interval, 0.63 to 0.76). Age-adjusted rates in men were 5.0 times those of women. Age-adjusted rates in blacks were 3.7 times those of whites. The age-adjusted seroconversion rate in Marine Corps personnel was 0.28 per 1000 person-years (95% confidence interval, 0.22 to 0.36). Similar demographic patterns were present in the Marine Corps and the US Navy. This study is one of the first reports of incidence of human immunodeficiency virus seroconversion by demographic characteristics in a large, young, and apparently healthy population.

Cytochrome P450IA1 induction and localization in endothelium of vertebrate (teleost) heart

Previous studies have shown that high levels of cytochrome P450 can occur in cardiac microsomes of vertebrates [Mol. Pharmacol. 21:517-526, (1982)]. Here we identify the dominant cardiac P450 in the marine fish scup as P450E, a teleost representative of P450IA1, and we describe its restricted cellular localization in the heart. Treatment of scup with beta-naphthoflavone produced an unusually strong (10-fold) induction of spectrally measured P450 in cardiac microsomes, with specific content reaching levels (0.5 nmol/mg) similar to those induced in scup liver. Microsomal ethoxyresorufin O-deethylase and aryl hydrocarbon hydroxylase activities, catalytic functions of scup P450E, were induced in parallel with P450 content. Similar induction was seen in both atrium and ventricle. Immunoblot analysis with monoclonal antibody 1-12-3, specific to scup P450E and other vertebrate P450IA1 proteins, showed that this hydrocarbon-inducible P450 is the dominant and possibly sole P450 form in heart microsomes of experimentally induced animals. Immunohistochemical analysis of scup heart sections (2-4-microns) with monoclonal antibody 1-12-3 revealed that P450E was detectable only in endothelial cells of the endocardium and of the coronary vasculature. A similar endothelial cell localization of the monoclonal antibody 1-12-3 epitope was observed in heart of rainbow trout, induced with beta-naphthoflavone, indicating a general nature for the endothelial localization of induced cardiac P450. Morphometric analysis showed that endothelium could constitute 8-9% of the volume of teleost heart, from which we calculate that P450IA1 could account for as much as 25% of the endothelial cell microsomal protein. Heart microsomes of untreated animals from contaminated environments also contained high levels of P450E, indicating that induction like that caused by beta-naphthoflavone could occur with chemicals in the environment. Strongly induced P450E (P450IA1) in endothelium could play a critical role in chemical-biological interactions involving xenobiotics affecting the vasculature of the heart or other organs.

Association of 3'----5' exodeoxyribonuclease activity with DNA replitase complex from S-phase Chinese hamster embryo fibroblast cells

DNA replitase has been described as a complex of enzymes/proteins that are associated with both DNA precursor biosynthesis and DNA replication in mammalian cells [Reddy, G. P. V., and Pardee, A. B. (1980) Proc. Natl. Acad. Sci. USA 77, 3312-3316]. We demonstrate for the first time a 3'----5' exodeoxyribonuclease activity is associated with the replitase complex. As much as 60% of this exonuclease activity was similar to that associated with DNA polymerase delta based upon its sensitivity to inhibition by GMP and by butyl-phenyl-deoxyguanosine triphosphate (BuPdGTP). Association of 3'----5' exonuclease activity with the DNA polymerase in the replitase complex was also demonstrated by analyzing dTTP turnover to dTMP in an in vitro DNA polymerase assay system. The DNA polymerase activity in replitase complex exhibited a sensitivity to BuPdGTP which both was similar to that of DNA replication in permeable cells and was intermediate between the BuPdGTP inhibition of purified DNA polymerases alpha and delta. These studies suggest that the replitase complex contains 3'----5' exonuclease activity associated with the DNA polymerase activity responsible for nuclear DNA replication in mammalian cells. Further studies are required to determine if these activities are at least partially attributed to DNA polymerase delta.

DNA repair synthesis in isolated rainbow trout liver cells

Isolated trout liver cells were treated with lysolecithin to produce an in situ system for characterizing DNA repair in teleosts. In this preparation, the integrity of the plasma membrane is altered, nuclei remain intact, and the concentrations of dNTPs and nucleotide analogs, which normally do not penetrate intact plasma membranes, can be controlled. Following lysolecithin treatment, 50% of the total cellular protein and nearly 75% of total lactate dehydrogenase activity was released from the liver cells. Microscopic examination indicated that the integrity of the plasma membrane of trout hepatocytes was disrupted by lysolecithin; however, smaller nonhepatocytic liver cells were resistant to the disrupting effects of this detergent. Bleomycin induced DNA repair synthesis in lysolecithin-treated cells, as demonstrated by CsCl gradient analysis of 5-bromo, 2'-deoxyuridine, 5'-triphosphate-labeled DNA. Optimal conditions for bleomycin-induced DNA repair synthesis in lysolecithin-treated trout liver cells were considerably different from that in lysolecithin-treated mammalian cells. Bleomycin-induced DNA repair synthesis was lower in lysolecithin-treated trout liver cells than in lysolecithin-treated mammalian cells at identical concentrations of 2'-deoxyribonucleoside, 5'-triphosphates (dNTPs), suggesting the decreased sensitivity of trout cells in unscheduled DNA synthesis assays can be attributed to factors other than differences in dNTP pools. Bleomycin-induced DNA repair synthesis in trout hepatocytes was shown to be very sensitive to inhibition by 2', 3'-dideoxythymidine, 5'-triphosphate and was resistant to inhibition by cytosine arabinoside, 5'-triphosphate, butylphenyldeoxyguanosine, 5'-triphosphate and aphidicolin. These observations indicate repair of bleomycin-induced DNA damage in trout cells occurs through a mechanism similar to that in mammalian cells, utilizing DNA polymerase beta.