Chemical dynamics in proteins: the photoisomerization of retinal in bacteriorhodopsin.

Chemical dynamics in proteins are discussed, with bacteriorhodopsin serving as a model system. Ultrafast time-resolved methods used to probe the chemical dynamics of retinal photoisomerization in bacteriorhodopsin are discussed, along with future prospects for ultrafast time-resolved crystallography. The photoisomerization of retinal in bacteriorhodopsin is far more selective and efficient than in solution, the origins of which are discussed in the context of a three-state model for the photoisomerization reaction coordinate. The chemical dynamics are complex, with the excited-state relaxation exhibiting a multiexponential decay with well-defined rate constants. Possible origins for the two major components are also discussed.

Lung fiber burden in the Nottingham gas mask cohort.

A cohort of 1,154 employees, mainly women, who had worked 1940-1945 on the manufacture of military gas masks using filter pads containing 20% crocidolite, was traced through 2003, by which time 65 were known to have died from mesothelioma. The last known death with mesothelioma was in 1994, whereas a further 5 cases would have been expected in those with known duration of exposure. Lung tissue samples, from 50 deaths from mesothelioma and 20 other causes, had been analyzed for mineral fiber content. For ten of the mesothelioma cases data on fiber size were collected. Crocidolite fiber concentrations were analyzed in relation to exposure by time and duration. Fiber concentrations overall fell fairly steadily by decade of death, and increased with length of exposure up to 36 months and then fell sharply. The annual rate of elimination estimated by regression was 7.5% corresponding to a half life of 9.2 years. The proportion of fibers longer than 6 mum increased over time implying that the shorter fibers were eliminated more rapidly than the longer ones. The decline in concentrations with time confirms the hypothesis that crocidolite and, by inference, other amphibole fibers are slowly removed from the lung, but since the longer more carcinogenic fibers were cleared more slowly it is unclear to what extent this clearance explains the slowing down of the increase in mesothelioma mortality from about 40 years from the most recent exposure. The exact biostatistical models which most closely conform with the data remain open to question.

Lung cancer and exposure to arsenic in rural Bangladesh.

BACKGROUND: Arsenic is a known carcinogen but the risk of lung cancer from the widespread contamination of drinking water in rural Bangladesh has not been estimated. OBJECTIVES: To determine whether estimated exposure of villagers in Bangladesh to arsenic in drinking water differed between those with lung cancer and those with non-malignant lesions. METHODS: Data were obtained from 7286 subjects who underwent lung biopsy in 2003-2006 at a diagnostic centre taking referrals from throughout Bangladesh. Analysis was limited to 5372 people living in villages for the last 10 years who reported using tube well water. Of these, 3223 with a primary lung tumour were enrolled as cases and 1588 with non-malignant lesions as referents in an unmatched analysis. Arsenic exposure was estimated by average concentrations for each of 64 districts. Logistic regression was used to test the effects of age, arsenic and smoking on risk and to investigate relationship to cell type. RESULTS: Male cases were older than referents and more likely to smoke, to smoke >20 units/day and to smoke bidi-small, hand-rolled cigarettes. Odds ratios for lung cancer increased steadily with mean arsenic concentration, but the confidence interval excluded 1.0 only at concentrations >100 mug/l (OR 1.45, 95% CI 1.16 to 1.80). This trend was seen only in smokers where the increased risk at >100 mug/l was 1.65 (95% CI 1.25 to 2.18). A similar trend was seen in women smokers. Squamous cell lung cancer was more frequent in smokers and, having adjusted for smoking, in districts with arsenic concentrations >100 mug/l. CONCLUSIONS: Among Bangladeshis who smoke, those whose drinking water is contaminated with arsenic at concentrations >100 mug/l are at increased risk of lung cancer. With high levels of exposure misclassification and short latency of exposure, the study cannot estimate or exclude the likely long term risk in non-smokers and at lower arsenic concentrations.

Sixty years on: the price of assembling military gas masks in 1940.

BACKGROUND: Between 1940 and 1944 military gas masks with filter pads containing 20% crocidolite were assembled in a Nottingham factory. METHODS: Records supplied by the late Professor Stephen Jones were of 1154 persons, mainly women, who had worked in the factory during this period; they included many deaths from mesothelioma. A systematic effort was therefore made to establish causes of death for the whole cohort. RESULTS: Of 640 employees with full name and sex recorded, 567 (89%) were traced. Of these, 491 had died, including 65 from mesothelioma, though only 54 were certified as such. After exclusion of these 54, standardised mortality ratios were significantly raised for respiratory cancer (SMR 2.5) and carcinomatosis (SMR 3.2). The pattern of mortality in the remaining 514 employees without full identification was similar, but a low tracing rate (40%) did not justify their further analysis. The first death from mesothelioma was in 1963 (22 years after first exposure) and the last in 1994, whereas a further 5.0 cases would have been expected between 1996 and 2003 (p = 0.0065). CONCLUSION: These findings in a cohort followed over 60 years after brief exposure to crocidolite confirm a high and specific risk of mesothelioma (28% peritoneal) and perhaps of lung cancer some 20-50 years later. The statistically significant absence of further mesothelioma cases during the past eight years suggests that crocidolite, though durable, is slowly removed.

The radiological properties of a novel lung tissue substitute.

Lung phantoms have been manufactured using commercially available, polyurethane foam products. Some of these materials are no longer available; therefore, a new lung tissue substitute was developed. The elemental composition and radiological properties of the new lung tissue substitute are described in this paper. Because the lung tissue substitute will be used to manufacture phantom lungs that will be used to evaluate chest counting systems, it is necessary to know the radiological properties of the material. These properties must be compared with reference materials and materials that have been used for lung phantoms in the past. The radiological properties of interest include the electron density, mean excitation energy, electron stopping power and photon mass attenuation coefficients. In all these properties, the calculated values for the new lung tissue substitute closely matched the calculated values of ICRU Publication 44 lung tissue. Good agreement was also found when the new lung tissue substitute was compared with the Griffith lung tissue substitute described by the ICRU. The new material was determined to be an excellent lung tissue substitute.

Incidence by occupation and industry of acute work related respiratory diseases in the UK, 1992-2001.

AIMS: To summarise incidence rates and epidemiological characteristics of new cases of work related respiratory disease reported by specialist physicians in thoracic and occupational medicine, with particular reference to occupation, industry, and causal agents for asthma, inhalation accidents, and allergic alveolitis. METHODS: Cases reported 1992-2001 to the SWORD and OPRA national surveillance schemes, in which almost all UK chest and occupational physicians participate, were analysed by age, sex, cause, occupation, and industry, with incidence rates calculated against appropriate denominators. RESULTS: Excluding diseases of long latency, infrequently seen by occupational physicians, the distribution of diagnoses in the two specialties was similar, but with rates generally much higher in occupational than chest physicians. Occupational asthma was responsible for about 25% of cases overall, affecting mainly craft related occupations and machinists, and most often attributed to isocyanates, metals, grains, wood dusts, solders, and welding fume. These same occupations were those at highest risk from inhalation injuries, most frequently caused by irritant gases, vapours, and fume. Among medical technicians and nurses, however, glutaraldehyde and latex were the main causes of occupational asthma. Allergic alveolitis was seldom reported, with almost all cases in agriculture, forestry, and fishing. CONCLUSION: During the 10 year period studied, there were few changes in level of reported incidence, apart from some decline in occupational asthma and inhalation injuries. These results and their implications should be distinguished from much higher estimates of asthma made worse by work derived from population surveys, based on prevalence rather than incidence, and self-reported symptoms rather than diagnoses made by specialist physicians. Even so, the reported incidence of new cases of acute respiratory illness caused by work remains substantial.

The biologic implications of HLA.

The state of the study of the HLA locus is described in brief, and several areas of human biology that may be affected by a fuller understanding of this complex genetic system are pointed out.

Cocaine-induced erythrocytosis and increase in von Willebrand factor: evidence for drug-related blood doping and prothrombotic effects.

BACKGROUND: Mechanisms that mediate cocaine-induced cardiovascular events following vasoconstriction are incompletely understood. OBJECTIVE: To examine the effects of cocaine in moderate doses on hematologic and hemostatic parameters that influence blood viscosity and thrombotic potential. METHODS: Changes in hemoglobin concentration, hematocrit, and red blood cell counts were measured in human subjects who met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for long-term cocaine abuse, before and sequentially after moderate intranasal and intravenous doses of cocaine. Hemostatic parameters, including von Willebrand factor, fibrinolytic activity, fibrinogen, plasminogen activator inhibitor antigen, and tissue-type plasminogen activator antigen, were sequentially measured after intravenous cocaine or saline placebo with cardiac troponin subunits T and I. RESULTS: Hemoglobin level (P= .002), hematocrit (P =.01), and red blood cell counts (P = .04) significantly increased from 4% to 6% over baseline from 10 to 30 minutes after intranasal (n = 14) and intravenous (n = 7) cocaine administration in doses of 0.9 mg/kg and 0.4 mg/kg, respectively, with no change in white blood cell or platelet counts. There was a significant increase (P =.03) in von Willebrand factor from 30 to 240 minutes, peaking at 40% over baseline following intravenous cocaine administration in a dose of 0.4 mg/kg (n = 12), with no change after 0.2 mg/kg (n = 3) or placebo (n = 6). Other hemostatic factors, creatinine, blood urea nitrogen, and cardiac troponin subunits T and I showed no changes. CONCLUSIONS: Cocaine induced a transient erythrocytosis that may increase blood viscosity while maintaining tissue oxygenation during vasoconstriction. An increase in von Willebrand factor without a compensatory change in endogenous fibrinolysis may trigger platelet adhesion, aggregation, and intravascular thrombosis.

Imported rickettsial disease: clinical and epidemiologic features.

PURPOSE AND METHODS: The rickettsioses continue to constitute major health problems in many parts of the world. With increasing international travel, recognition of rickettsial diseases by physicians is becoming more important. The clinical features of four cases of rickettsial disease imported into Canada over a five-year period are presented; two patients with tick typhus (Rickettsia conorii), one patient with scrub typhus (R. tsutsugamushi), and one patient with murine typhus (R. typhi). We also present the North American data over the past 10 years from the Centers for Disease Control (CDC) (Atlanta). RESULTS: Since 1983 in the United States, three cases of imported scrub typhus, all after travel to India, were confirmed, as well as six cases of murine typhus after travel to southeast Asia. At the CDC, 67 imported cases of tick typhus have been confirmed by indirect fluorescent antibody test since 1976; most illnesses occurred after travel to Africa. CONCLUSION: Rickettsial diseases are underrecognized by physicians, who should consider these diagnoses in travelers returning from endemic areas. Since effective treatment is available, prompt diagnosis and treatment are important. In all cases, specific serologic confirmation should be obtained.

Association of serum concentration of soluble class I HLA with HLA allotypes.

We correlated serum concentrations of soluble class I HLA antigens (S-HLA-I) with HLA allotypes in 82 unrelated Caucasian and 58 unrelated African-American putatively normal subjects, as well as in 31 individuals with stable, normally functioning liver transplants. Caucasian and African-American subjects with HLA-A23 or HLA-A24 were high secretors of S-HLA-I. We also observed that some HLA-A allotypes associated with high serum concentrations of S-HLA-I were ethnicity specific. HLA-A33 was associated with high S-HLA-I secretion in African-Americans but not in Caucasians. HLA-A29 was associated with high S-HLA-I secretion in Caucasians but not in African-Americans. All liver transplant recipients studied who were high secretors of S-HLA-I postoperatively carried HLA-A24 or HLA-A29. (There were no HLA-A33 or HLA-A23 allotypes in this group.) The "secretor genes," however, may be autogenous or allogenic (i.e., either donor or recipient HLA-A24 or HLA-A29 resulted in the observed high secretor status in liver transplant recipients after transplantation). It is noteworthy that serum S-HLA-I concentrations were low in all subjects with HLA-A2 regardless of whether the HLA-A2 was of recipient or donor origin. This finding suggests that HLA-A2 could have a suppressive effect on S-HLA-I secretion.

A heterophile system in human renal transplantation. IV. Natural immunity and its genetic implications.

Natural heterophile immunity was studied in 949 individuals including 41 recipients and donors of renal transplants and 141 families. The prevalence and strength of the natural immunity was at its maximum during the first two decades of life and declined thereafter. The population could be divided into three groups: one with natural immunity to heterophile transplantation antigens (HT-A), one with a heterophile immunity which was not (anti-HT-A) (i.e., anti-HX-A), and one group which had no heterophile immunity. Transplantation among these groups yielded results which along with family studies and mathematical considerations suggest that the HT-A system is controlled by a single genetic locus comprised of one dominant and one recessive allele.

A heterophile system in human renal transplantation. VII. The antigen is an intrinsic component of several human tissues.

The presence or absence of the heterophile transplantation antigen was sought in renal tissue from stillborn infants, primary cell cultures, and several organs from adult human cadavers. The heterophile transplantation antigen was found in renal tissue at birth, was retained in human renal cell culture, and was present in human organs other than kidney. The most likely explanation for these results is that the heterophile transplantation antigen is an intrinsic component of many human tissues.

A heterophile system in human renal transplantation. X. HTA sensitivity includes sensitivity to human B lymphocytes.

Antibodies that react with heterophile transplantation antigen (HTA) have been shown previously not to react with HLA-A, B, or C antigens. This paper presents evidence that anti-HTA does react with a subpopulation of human lymphocytes which is comprised primarily of B cells. Anti-HTA reactivity was removed from sera by absorption with each of three different human B lymphocyte cell lines, but it was unaffected by absorption with platelets or thymocytes. Selected high titer anti-HTA sera absorbed with human platelets, human blood group type AB erythrocytes, and sheep erythrocytes caused lysis of a lymphocyte subpopulation principally composed of B lymphocytes. Absorption of these sera with rat erythrocytes removed both lymphocytic activity and anti-HTA activity. Antibody recovered by affinity purification with rat erythrocyte membrane preparations contained both lymphocytic and anti-HTA reactivity. These data, considered with previous studies, seem to establish that B cell sensitization may be acquired by a substantial segment of the population by natural immunization from enteric flora and/or by infections with enteric bacteria.

A heterophile system in human renal transplantation. V. Relationship of heterophile transplantation antigen and common antigen of Enterobacteriaceae.

Heterophile transplantation antigen and common antigen of Enterobacteriaceae appear serologically to be separate specificities. However, both antigens are common to Enterobacteriaceae, rat erythrocytes, and some human kidneys. Both antigens are obtained from various tissues by the same chemical procedure. Immunity to each antigen is frequently produced by renal transplantation. We suggest that the antigens are either separate molecules which are similar in chemical structure in the region of the antigenic determinant as well as in tissue distribution or separate reactive sites located on the same molecule. The possibility that common antigen may be a human alloantigen raises theoretical possibilities relative to susceptibility to infection and pyelonephritis, as well as to its relationship to histocompatibility.

A heterophile system in human renal transplantation. IX. Comparison of heterophile transplantation antibodies to antivascular endothelial cell antibodies.

Antibodies to heterophile transplant antigen (HTA) were tested for reactivity with antigens on human umbilical cord antigenic specificities on isolated endothelial cells. Furthermore, there are antigens on endothelial cells that are distinct from HLA-A,B, C, and from HTA. It is concluded that the HTA and the VEC antigens are different.

A heterophile system in human renal transplantation. VIII. The morphological distribution of the antigen in rat tissues.

The morphological distribution of heterophile transplant antigen (HTA) was determined in rat tissues using an indirect immunofluorescence technique. Human anti-HTA sera were used to localize HTA in rat kidney, liver, heart, skeletal muscle, spleen, and stomach. HTA was found in basement membrane and supporting stromal elements of all tissues studied. In the kidney, HTA was demonstrated in tubular basement membrane but not glomerular basement membrane. No evidence for cell surface antigen distribution could be ascertained except for erythrocyte membranes. HTA was not found on endothelium of rat blood vessels. We know of no antigens previously implicated in histocompatibility that are stromal in location.

Soluble HLA class II concentrations in normal individuals and transplant recipients. Comparison with soluble HLA class I concentrations.

We developed an ELISA to quantify soluble HLA class II (S-HLA-II) in 702 sera obtained from normal subjects, patients with end-stage renal disease, and recipients of renal, hepatic, and cardiac transplants. Concentrations of S-HLA-II were detectable in 124 of 126 normal individuals. The distribution of normal values described a monophasic curve with a skewed distribution. In transplant recipients, there were no differences between preoperative and posttransplant values, but values in liver patients were significantly higher than in kidney patients, and values for heart patients were lowest of all groups. There were periodic variations in concentrations in individual patients, but these were unrelated to rejection, infection, or any other apparent clinical event. S-HLA-II was consistently present in the urine. All of these observations contrast with previous observations concerning soluble HLA class I (S-HLA-I) molecules, which were almost the precise reverse. It seems likely that these clear differences in S-HLA-II and S-HLA-I concentrations relate to different physiologic processes in either production, function, or elimination.

Both ischemic and pharmacological preconditioning decrease hepatic leukocyte/endothelial cell interactions.

BACKGROUND: Ischemic preconditioning has been shown to protect some tissues from ischemia/reperfusion (I/R) injury. Adenosine is believed to play an important role by attenuating leukocyte-endothelial cell adhesive interactions. Dipyridamole increases adenosine bioavailability. The purpose of this study was to evaluate the effects of mechanical (MPC) and pharmacological preconditioning (PPC) on leukocyte endothelial cell interaction in hepatic I/R injury. METHODS: C57BL6 mice were subjected to 30 min of ischemia to the left lobe of the liver. Groups tested at 30 min, 2, 5, 12, and 24 hr of reperfusion had 1) sham laparotomy (n = 10, 2) I/R (n = 25), 3) ischemic preconditioning with 5 min of ischemia and 10 min reperfusion before I/R (n = 25), and 4) (PPC) with dipyridamole (n = 25). Intravital microscopic examination was used to assess leukocyte/endothelial cell adhesion. Blood was drawn for leukocyte counts and liver function tests. RESULTS: A significant decrease in leukocyte rolling was observed at 30-min and 5-hr reperfusion intervals in the PPC and ischemic preconditioning groups compared with the I/R group. A significant decrease in leukocyte saltation was also observed in the PPC and MPC groups at 2, 5, and 12 hr of reperfusion when compared with the I/R group. aspartate aminotransferase was significantly decreased in the 5-hr preconditioning groups. There was not a significant decrease in the white blood cell count because of PPC or MPC vs. I/R CONCLUSIONS: Preconditioning decreases endothelial/ leukocyte interaction and reduces liver damage as measured by aspartate aminotransferase. These data prove that IPC and PPC provide some degree of hepatic protection in I/R injury.

Serologic allogeneic chimerism.

BACKGROUND: At least some transplanted livers secrete soluble human leukocyte antigens (sHLA) of donor phenotype into the body fluids of recipients. The individuals in whom this phenomenon occurs are by definition serologic allogeneic chimeras. Because an allogeneic transplanted liver may induce tolerance to itself and other organs in animals of the donor strain, and because maintenance of a soluble antigen in the circulation of any animal in sufficient quantity for a sufficient period generally leads to tolerance, this phenomenon may be biologically important. This study was performed to determine how common this phenomenon is and whether it occurs after transplantation of organs other than the liver. METHODS: We studied 445 serum samples obtained from transplant recipients (liver, n=12; kidney, n=18; and heart, n=8) before and at various intervals after transplantation. All patients studied had allografts that had functioned for more than 1 year. We used an enzyme-linked immunosorbent assay to quantitate sHLA-A2 and sHLA-A1/A3/A11 (as a cross-reacting group). Donor and recipient combinations were selected in which measurable allotypes in donors were not present in recipients. In some instances, an additional allotype was present in a recipient but not in a donor. RESULTS: All liver transplant recipients had detectable donor sHLA in their serum samples after transplantation. In 72% of kidney and 50% of heart transplant recipients, donor sHLA was found persistently in serum samples obtained after transplantation. Interestingly, all heart transplant recipients of HLA-A3, but none of HLA-A2, had detectable donor sHLA in their serum samples, a finding that may be due to technical reasons. High and stable serum concentrations of donor sHLA characterize long-term stable allograft function. CONCLUSIONS: Donor sHLA is produced by all transplanted livers, most transplanted kidneys, and at least half of (but probably more) transplanted hearts. The hypothesis that donor sHLA may be tolerogenic to liver transplants can be expanded to include kidney and heart transplants.

HLA in human serum--quantitation of class I by enzyme immunoassay.

A solid-phase, enzyme-linked immunoassay was used to quantitate the soluble fraction of HLA-class I. The sera of 318 individuals were studied, as well as the urine of six individuals with normal renal function. The stability of blood concentrations of the soluble HLA was also evaluated. The data justify the following six conclusions. (1) All normal people have circulating HLA (mean = 357 ng/ml). (2) The population can be divided into one group of low secretors (mean = 162.4 +/- 65.2 ng/ml) and another group of high secretors (mean = 540.7 +/- 185.9 ng/ml) (P less than 0.01). (3) Blood levels in each individual are reasonably consistent over short (days) and long (years) periods of time. (4) The mean concentration of soluble HLA-class I in all renal failure patients was 590 ng/ml, significantly higher than normal (P = less than 0.05); it was highest in patients on peritoneal dialysis (mean = 683 ng/ml) in spite of substantial chronic loss in peritoneal dialysate. (5) Renal allograft recipients with stable allograft function also had mean values greater than normal at 554 ng/ml (P less than 0.05). (6) Soluble HLA-class I was not detected in the urine of individuals with normal renal function.