Genome annotation of five Mycoplasma canis strains.

To understand its potential to cause invasive disease, the genome of Mycoplasma canis strain PG14(T) from a dog's throat was compared to those of isolates from the genital tract or brain of dogs. The average nucleotide identity between strain pairs is 98%, and their genome annotations are similar.

Circulatory heat sources for canine respiratory heat exchange.

We assessed the roles of the pulmonary and bronchial circulations as potential heat sources to the pulmonary airways during respiratory heat loss, by observing the changes in airstream temperature that accompanied temporary occlusion of the pulmonary or bronchial circulations. Baseline end-expiratory and end-inspiratory airstream temperatures were 35.4 +/- 0.2 degrees C (SEM) and 30.9 +/- 0.3 degrees C, respectively, among all trials. With occlusion of the lower lobe pulmonary arteries for 3 min ipsilateral end-expiratory and end-inspiratory airstream temperatures fell by 2.8 +/- 0.2 and 1.1 +/- 0.2 degrees C, respectively, during hyperpnea with room temperature air, and by 3.5 +/- 0.5 and 1.8 +/- 0.2 degrees C, respectively, during hyperpnea with frigid air. In marked contrast, interruption of the bronchial circulation for 3 min had no effect on airstream temperatures. These data indicate that under these conditions, the pulmonary circulation, but not the bronchial circulation, serves as an important local heat source for respiratory heat exchange within the pulmonary airways.

Patterns of mortality among commercial pressmen.

A proportionate analysis of cause of death in 1,401 commercial pressmen was initiated following a report of a cancer cluster in this group. The study found a significant elevated risk of all cancers [proportionate mortality ratio (PMR) = 127] and cancers of the lymphatic and hematopoietic system (PMR = 122), with non-Hodgkin's lymphomas responsible for much of the excess. Three deaths in the cohort were attributed to myelofibrosis, a rare disease associated with benzene exposure. A significantly elevated PMR was also detected for colorectal cancer (PMR = 171) and, among those employed 20 years or more, for cancers of the liver (PMR = 216) and pancreas (PMR = 162). No excess risk of bladder or lung cancer or leukemia was seen. Proportionate mortality analyses rarely show excess risk of both cancer and heart disease in a working population. Surprisingly, a significantly elevated risk of arteriosclerotic heart disease (PMR = 113) was found in this group. These findings indicate that solvent exposure may be associated with excess mortality risk in commercial pressmen.

Membrane damage by a toxin from the sea anemone Stoichactis helianthus. I. Formation of transmembrane channels in lipid bilayers.

The addition of nanomolar amounts of a toxin preparation derived from the sea anemone Stoichactis helianthus to black lipid membranes increases their electrical conductance by one million-fold. In addition, the membranes become permeable predominantly to monovalent cations. The elevated bilayer conductance is voltage-dependent, and the current-voltage curves of these bilayers display rectification as well as a region of negative resistance. The membrane activity of the toxin is proportional to the third power of its concentration, and at very low concentrations the membrane conductance increases in discrete uniform steps. These observations indicate that the mechanism of toxin action involves the formation of transmembrane channels constructed by the aggregation of protein molecules which are inserted in the bilayer. The voltage-dependent membrane conductance arises from two distinct channel characteristics: (1) the unit conductance of individual channels is dependent on the polarity of applied voltage; (2) the number of ion-conducting channels is influenced by the polarity as well as the magnitude of applied potential. It is believed that these effects are due to the influence of an electric field on the insertion of toxin molecules into the bilayer or on their subsequent association with each other to produce channels. Partial chemical characterization of the toxin material has shown that the membrane active factor is a basic protein with a molecular weight of 17,500.

Membrane damage by a toxin from the sea anemone Stoichactis helianthus. II. Effect of membrane lipid composition in a liposome system.

In the first paper of this series, it was shown that a toxin from the sea anemone Stoichactis helianthus increased the permeability of black lipid membranes due to transmembrane channel formation. In the present study, we have used liposomes to examine the reactivity of the toxin with different phospholipids. Membrane damage was assessed by measuring the release of 86Rb+ and 14C-labeled membrane lipid. For the different lipids, the rank order of marker release was: sphingomyelin greater than C18 : 2 phosphatidylcholine greater than C18 : 1 phosphatidylcholine greater than C18 : 0 phosphatidylcholine greater than C16 : 0 phosphatidylcholine = C14 : 0 phosphatidylcholine. In C14 : 0 and C16 : 0 phosphatidylcholine liposomes there was no 14C-labeled lipid release and only 13 to 16% 86 Rb+ release which corresponds to the 86Rb+ content in the outermost aqueous shell of multilamellar liposomes. This indicates that membrane damage was limited to the outermost bilayer. In liposomes prepared with the other lipids, the extent of release of both markers increased proportionately with the length and the degree of unsaturation of the lipids' acyl side chains. Spingomyelin liposomes were the most susceptible with 47% of the 14C-labeled lipid marker and 90% of the 86Rb+ marker being released. The large extent of 14C-labeled lipid release is attributed to a detergent-like activity of the toxin which presumably is due to the amphipathic nature of the protein. Thus, the toxin can inflict membranrtance of one mechanism or the other apparently varies depending on membrane structure and lipid composition.

Mortality among urban bus drivers.

Driving a bus in urban areas is considered to be a highly stressful occupation, one which also involves exposure to air pollutants generated by motor vehicles. In order to investigate the potential health hazards associated with this occupation, the causes of death of 376 New York City bus drivers were studied. Analyses of proportionate mortality found a significant excess due to ischaemic heart disease in drivers in both races combined (proportionate mortality ratio PMR = 1.23), and among the 58 non-white drivers (PMR = 1.72). A significantly elevated risk of death from mental, psychoneurotic and personality disorders (ICDA Ninth Revision 290-319, which includes alcoholism and narcotics abuse) was also found in the combined group (PMR = 2.66), and among the white drivers (PMR = 3.05). For all drivers, PMRs for all malignant neoplasms (PMR = 1.26) and for cancer of the oesophagus (PMR = 2.54) were significantly elevated. No cancer sites were found to be significantly elevated in the proportionate mortality analyses by race. These findings are consistent with the growing body of literature linking job strain with cardiovascular disease among bus drivers.

Does low-level lead exposure increase risk of death? A mortality study of newspaper printers.

This exploratory study examined the mortality experience of a cohort of newspaper printers in order to investigate the effects of low-level exposure to lead. In this industry, historic lead exposure levels have been below the current US permissible exposure level (PEL) of 50 micrograms/m3. The study population was 1261 typesetters, employed in 1961 and followed until the end of 1984; this was a cohort of convenience, assembled as a comparison for a different study. Standardized mortality ratios (SMRs) were calculated using New York City comparison rates. The all-cause SMR was 0.74, and was significantly different from 1.00. Other statistically significant deficits were deaths from arteriosclerotic heart disease (SMR = 0.63) and non-malignant diseases of the respiratory system (SMR = 0.57) and digestive system (SMR = 0.65). These can be attributed to the comparison bias known as the healthy worker effect. The SMR for cerebrovascular disease (CVD) was 1.35, on the edge of statistical significance (95% confidence interval (CI): 0.98-1.82). When the cohort was stratified by years of union membership, a surrogate for length of exposure, only one cause of death was significantly elevated. For those printers employed for 30 years or more, the CVD SMR was 1.68 (95% CI: 1.18-2.31; p = 0.002). No significant excesses were seen for any other cause of death in any exposure stratum. Several studies of workers with much higher levels of lead exposure have reported elevated CVD risk. These findings suggest the possibility that lead exposure at levels below the current US PEL may also be associated with CVD mortality.

Exposure of sheet-metal workers to asbestos during the construction and renovation of commercial buildings in New York City. A case study in social medicine.

New York City sheet-metal workers have a history of significant exposure to asbestos. Prior to 1972 when the use of sprayed asbestos insulation was banned in New York City, sheet-metal workers involved in building construction were exposed as they worked adjacent to spraying operations. Subsequent to that date, exposure continued as they renovated these same buildings. In 1982 the Occupational Health Program of Montefiore Medical Center and the Albert Einstein College of Medicine initiated a multidimensional asbestos evaluation and intervention program for the sheet-metal industry and union in New York. The long-term goal of the program was to eliminate asbestos exposure through the safe, systematic removal of asbestos in New York City buildings, most likely a legislated solution. In the short term, we attempted to assess and reduce asbestos exposure in the sheet-metal trade by a series of steps consisting of: mortality and morbidity studies; a medical audit of clinical screening services provided to sheet-metal workers; a comprehensive health education program; development of safe work practices; evaluation of personal protective equipment; and investigation into and support of legislative and regulatory solutions to the problem of asbestos contamination of commercial buildings. This intervention can be seen as a case study in the practice of social medicine.

Vertical prisms. How to avoid them.

Prescribing vertical prisms not infrequently leads to unsightly spectacles at best, and computing them may lead to errors at worst. Prismatic compensation for a particular reading point is of little value when the patient uses other eccentric portions of the lens, and it is not necessary if the patient learns to use (or continues to use) the optical centers. Clinical evaluation of eye-head posture and vertical phorias may reveal tell-tale clues in managing vertical imbalances in general and the anisometropic presbyope in particular.

Indications for prescribing spectacles.

Indications for spectacle correction are reviewed in the context of symptoms, pathophysiology, and prognostic efficacy. Criteria include improving acuity, restoring comfortable vision, enhancing visual efficiency, preventing progression, and assorted miscellaneous goals. Alternatives to spectacles and side effects are analyzed. Specific guidelines for individualized management are evaluated in terms of current research.

Indirect assessment of mucosal surface temperatures in the airways: theory and tests.

We developed and tested a method, based on conduction heat transfer analysis, to infer airway mucosal temperatures from airstream temperature-time profiles during breath-hold maneuvers. The method assumes that radial conduction of heat from the mucosal wall to inspired air dominates heat exchange during a breath-hold maneuver and uses a simplified conservation of energy analysis to extrapolate wall temperatures from air temperature vs. time profiles. Validation studies were performed by simultaneously measuring air and wall temperatures by use of a retractable basket probe in the upper airways of human volunteers and intrathoracic airways of paralyzed intubated dogs during breath holding. In both protocols, a good correlation was demonstrated between directly measured wall temperatures and those calculated from adjacent airstream temperature vs. time profiles during a breath hold. We then calculated intrathoracic bronchial wall temperatures from breath-hold airstream temperature-time profiles recorded in normal human subjects after cold air hyperpnea at 30 and 80 l/min. The calculations show airway wall temperatures in the upper intrathoracic airways that are below core body temperature during hyperpnea of frigid air and upper thoracic airways that are cooler than more peripheral airways. The data suggest that the magnitude of local intrathoracic heat/water flux is not represented by heat/water loss measurements at the airway opening. Both the magnitude and locus of heat transport during cold gas hyperventilation vary with changes in inspired gas temperature and minute ventilation; both may be important determinants of airway responses.

Computerized assessment of self-monitored blood glucose results using a Glucometer reflectance photometer with memory and microcomputer.

A microcomputer software package to receive, analyse, and present blood glucose/time information has been developed. Data input is accomplished automatically via interface to Glucometer reflectance photometer instruments which have been specially modified to retain glucose/time results by addition of a clock and electronic memory. This new development in self-monitoring of blood glucose (SMBG) has a number of advantages. It allows the rapid and meaningful analysis of large quantities of patient generated data to assess short- and long-term trends in BG patterns, and eliminates the tedium and possible errors of manual graphing. Patients were most interested in the positive feedback provided. The system has considerable potential in patient diabetes education and management.

Occupational cancer in the black population: the health effects of job discrimination.

Cancer mortality rates among black workers employed in several United States industries are higher than those of their white co-workers and of the national black population. As a result of discriminatory employment patterns, blacks are disproportionately employed in "high-hazard" jobs, where they are exposed to carcinogens and other disease-producing substances. The elevated cancer mortality rates in black workers in these industries are a direct consequence of discriminatory employment patterns. The implications of these findings for physician practice, research, and national regulatory policy are discussed.

A real-time system for the spectral analysis of the EEG.

We have developed an inexpensive and portable system for processing multiple channels of electroencephalograms (EEG) in real-time to assist the electroencephalographer in identifying subtle changes in these data, particularly in the interpretation of long records. Up to 16 channels of data are spectrally decomposed with a selection of bandwidth, windows, scaling methods, epoch averaging, and smoothing options available. The resulting power spectral estimate may be displayed or printed in a variety of formats, including color encoding of selectable spectral bands. Both the sampled EEG and its spectra may be stored for off-line reprocessing, for archiving, or for statistical analysis in the time or frequency domains.

Mercury poisoning in Nicaragua: a case study of the export of environmental and occupational health hazards by a multinational corporation.

Pennwalt Inc., a multinational chemical and pharmaceutical firm based in the United States, operates a chloralkali plant in Managua, Nicaragua. This plant utilizes elemental mercury in the production of chlorine and caustic soda for markets throughout Central America. The plant was recently found to be contaminating the waters of Lake Managua (on which the plant is located) with 2 to 4 tons of inorganic mercury effluent per year-over 40 tons in the 13-year history of the plant. Examination of the 152 workers employed in the plant showed that 56(37 percent) were suffering symptoms and signs of mercury poisoning, including tremors (in 45), memory and attention deficits (in 45) and paresthesias (in 52). Levels of airborne mercury vapor in the plant were found to range as high as 600 microgram/m3. (The airborne standard set by the U.S. Occupational Safety and Health Administration is 100 microgram/m3.) Workers in the plant had never been alerted to the hazards of mercury. The plant was found to be in deteriorated condition, with no recent investments in maintenance or modern safety equipment. It is reported that the parent corporation, Pennwalt, has been withdrawing capital from the operation (and from Nicaragua) since the fall of the Somoza regime.

Home health nursing: towards a professional practice model.

A rapidly growing caseload led this home healthcare agency in New England to develop and implement a new management structure built around the belief that 1) Professionals can manage their own practice and function as part of a self-directed work team; 2) Management's role is to foster an organizational culture which facilitates this; and 3) Total quality management is based on people-oriented service. A "flex-time" system, competitive compensation and empowerment stemming from responsible autonomy have begun to reduce turnover and enhance "word of mouth" advertising.