Protoperithecia in Neurospora crassa: technique for studying their development.

A technique is described which facilitates analysis of the development of individual protoperithecia in Neurospora crassa. The formation of this organelle proceeds in several clearly discernible steps beginning with the looping of a single hyphal filament and ending with a heavily pigmented, densely packed structure that is the mature protoperithecial structure. The effects of a number of environmental conditions on the development of protoperithecia in two wild types and in a female-sterile mutant strain, ty-1. are presented.

An increased risk for lung cancer mortality associated with sugarcane farming.

In a study to determine putative occupation-related factors responsible for the excessive mortality due to lung cancer in southern Louisiana, the next-of-kin were interviewed of 284 of 400 persons (71%) randomly sampled from a total of 815 persons who died of lung cancer during 1971 through 1977 and had lived in any of 10 parishes (counties) of southern Louisiana. Of the decedents, 108 (38%) had been employed for at least 6 months as sugarcane farm workers at some time during their lives. Logistic regression analysis indicated this industrial involvement differed significantly (P less than 0.0001) from that of a control group, consisting of persons who had died of any cause other than lung cancer and who were matched for year of death, age, sex race, and parish of residence; only 58 (20%) matched controls had had sugarcane farm employment (odds ratio = 2.4; 95% confidence interval, 2.0-2.9). Employment in other industries or tobacco consumption could not account for the elevated risk of lung cancer mortality associated with sugarcane farming. After adjustment for smoking, the relative risk estimate of lung cancer mortality for sugarcane farm workers was 2.4 (95% confidence limits, 1.7-3.6). The sugarcane farmers who died with lung cancer had worked for longer periods in the sugarcane farm industry than did those sugarcane farmers in whom lung cancer did not develop (P = 0.006). No specific histopathologic cell type was noted to be increased in persons who had been employed in sugarcane farming; however, 2 sugarcane farmers had had mesotheliomas.

Increased familial risk for lung cancer.

For the determination of whether lung cancer clusters in families, an analysis was conducted on demographic and morbidity-mortality data, occupational and industrial experiences, and tobacco use practices for family members of 336 deceased lung cancer probands and 307 controls (probands' spouses). First-degree relatives of probands, compared with first-degree relatives of controls, showed a strong excess risk for lung cancer. Overall, male relatives of probands had a greater risk for lung cancer than did their female counterparts, and the risk was fourfold for parents of probands as compared with parents of spouses. Female relatives of probands over 40 years old were at nine times higher risk than similarly aged female controls, even among those who were non-smokers and who had not reported excessive exposure to hazardous occupations; the risk was fourfold to sixfold for heavy smokers. After control for the confounding effects of age, sex, cigarette smoking, and occupational and industrial exposures, relationship to proband remained a significant determinant of lung cancer, with a 2.4-fold greater risk among relatives of probands.

Evidence for mendelian inheritance in the pathogenesis of lung cancer.

Segregation analyses that allowed for variable age of onset of lung cancer and smoking history were performed on 337 families, each ascertained through a lung cancer proband. Results indicated compatibility of the data with mendelian codominant inheritance of a rare major autosomal gene that produces earlier age of onset of the cancer. Segregation at this putative locus could account for 69% and 47% of the cumulative incidence of lung cancer in individuals up to ages 50 and 60, respectively. The gene was involved in only 22% of all lung cancers in persons up to age 70, a reflection of an increasing proportion of noncarriers succumbing to the effects of long-term exposure to tobacco.

Lung cancer detection and prevention: evidence for an interaction between smoking and genetic predisposition.

The initiation and promotion of cancer is thought to result from a series of genetic mutations, some of which may be inherited. Our analysis of 337 lung cancer families suggested that, after allowing for an individual's pack-years of tobacco use, the pattern of disease was best explained by Mendelian codominant inheritance of an allele that produced earlier age of onset. Since lung cancer rarely occurs in the absence of exposure to tobacco, differences in the prevalence of smoking across generations could have a profound influence on the fit of genetic models. In the present study, families were partitioned into two groups, based on the birth cohort of the proband, i.e., born before World War I (age at death, greater than or equal to 60 years) or born after World War I (age at death, less than 60 years). This partition was chosen because the year 1915 signaled the start of the dramatic rise in tobacco use in the United States. In younger proband families, in which parents were more likely to smoke, Mendelian codominant inheritance provided the best fit to the data. In older proband families, for whom smoking among parents was less prevalent, the "no major gene" and "environmental" hypotheses were rejected; however, no Mendelian models could be distinguished. If the results on the families with the most homogeneous exposure to tobacco across generations (born after World War I) reflect the true underlying biology, then the influence of genetic factors in the pathogenesis of lung has been underestimated; the cumulative probability of lung cancer at age 80 for a noncarrier of the gene, at the average level of tobacco consumption, is close to zero, implying that virtually all lung cancer occurs among gene carriers. Identification of this putative genetic factor has profound implications for the detection and prevention of lung cancer.

Segregation analysis of smoking-associated malignancies: evidence for Mendelian inheritance.

Tobacco consumption is an established risk factor for cancer at a number of sites: oral cavity, esophagus, nasopharynx, lung, larynx, pancreas, bladder, kidney, and uterine cervix. These sites also demonstrate familial aggregation. To determine if evidence exists for a major gene controlling susceptibility to smoking-associated cancers, maximum likelihood segregation analyses were performed on 337 families (3,276 individuals) ascertained through a deceased lung cancer proband. Models were fitted that allowed for personal tobacco use and variable age of onset. The hypotheses of environmental transmission and no major gene were rejected (P < 0.005), but none of the Mendelian models could be distinguished. According to Akaike's Information Criterion, Mendelian dominant inheritance of an allele that produces cancer at an earlier age of onset provided the best fit to the data. The model suggests that 62% of the population are susceptible, and that the mean age-of-onset differs for men and women: at the mean level of tobacco exposure, female gene carriers are affected, on average, 24 years earlier than non-carriers (77 vs. 101), while in males the difference was 20 years (71 vs. 91). These findings extend our earlier observations on the genetic epidemiology of lung cancer and suggest that Mendelian factors may influence the risk of cancers that are known to be smoking associated.

Histopathology of corneal leukoma and fibroma in the ACL syndrome.

Corneal tissues of four persons and a buccal fibroma from one of these persons with ACL syndrome, an autosomal dominant disorder, were evaluated clinically and microscopically. The corneal lesions appeared as a gray epithelial infiltrate over the cornea, destroying Bowman's membrane. Light and electron microscopic images of both types of lesions showed abnormal accumulation of granular mucopolysaccharide material and extensive aberrant orientation of collagen fibers. The authors postulate that the mucopolysaccharide accumulation is involved in the pathogenesis of the syndrome.

Maintenance of superior mesenteric arterial perfusion prevents increased intestinal mucosal permeability in endotoxic pigs.

Lipopolysaccharide increases intestinal mucosal permeability to hydrophilic compounds such as chromium 51-labeled edetate (51Cr-EDTA). We sought to determine whether this phenomenon is partly mediated by lipopolysaccharide-induced mesenteric hypoperfusion. We assessed permeability in an isolated segment of ileum by measuring plasma-to-lumen clearances (C) for two probes, 51Cr-EDTA and urea, and expressing the results as a ratio (CEDTA/CUREA). In control pigs (n = 6) resuscitated with Ringer's lactate (RL), mucosal permeability was unchanged during the 210-minute period of observation. In pigs (n = 7) infused with lipopolysaccharide (50 micrograms/kg) and similarly resuscitated with RL, mesenteric perfusion (Qsma) decreased significantly and permeability increased progressively and significantly. When endotoxic pigs (n = 6) were resuscitated with a regimen (RL plus hetastarch plus dobutamine) that preserved normal Qsma, lipopolysaccharide-induced mucosal hyperpermeability was prevented. Resuscitation of endotoxic pigs (n = 6) with RL plus hetastarch provided intermediate protection against both mesenteric hypoperfusion and increased permeability. These data suggest that diminished Qsma contributes to impaired ileal mucosal barrier function in experimental endotoxicosis.

Systemic and mesenteric O2 metabolism in endotoxic pigs: effect of ibuprofen and meclofenamate.

The effect of two chemically dissimilar cyclooxygenase inhibitors was studied in pentobarbital-anesthetized endotoxic pigs. Animals in groups II-IV were infused with Escherichia coli lipopolysaccharide (LPS, 150 micrograms/kg) and resuscitated with normal saline (1.2 ml.kg-1.min-1). Animals in group I (n = 4) were resuscitated as above but were not infused with LPS. Animals in group II (n = 7) served as endotoxic controls. Pigs in groups III (n = 6) and IV (n = 5) were pre- and posttreated with ibuprofen (10 mg/kg bolus then 10 mg.kg-1.h-1 and meclofenamate (5 mg/kg then 5 mg.kg-1.h-1, respectively. Ileal intramucosal hydrogen ion concentration [( H+]) was estimated tonometrically. In group I, cardiac index (CI), mean arterial pressure (MAP), superior mesenteric arterial perfusion (QSMA), and mesenteric O2 delivery (DO2) increased significantly, but other variables were unchanged. After infusion of LPS in group II, MAP and systemic vascular resistance index were markedly diminished but CI was well preserved. In this group, QSMA, systemic DO2, and mesenteric DO2 decreased, whereas systemic O2 uptake (VO2) and gut [H+] increased; mesenteric VO2 was unchanged. Compared with pigs in group II, pigs treated with ibuprofen or meclofenamate manifested improved systemic and mesenteric DO2. In groups III and IV, QSMA remained normal, increased systemic VO2 was not observed, and gut intramucosal acidosis was ameliorated. Increased intramucosal [H+] in group II suggests that QSMA was inadequate. The salutary effects of ibuprofen and meclofenamate suggest that inadequate mesenteric perfusion was mediated, at least in part, by cyclooxygenase-derived metabolites or arachidonic acid.

Ibuprofen improves survival but does not ameliorate increased gut mucosal permeability in endotoxic pigs.

Intravenous lipopolysaccharide (LPS) decreases superior mesenteric arterial blood flow and increases ileal mucosal permeability in pigs. We tested the hypothesis that these phenomena can be ameliorated by pretreatment and posttreatment with ibuprofen. Pentobarbital-anesthetized immature swine were mechanically ventilated (fraction of inspired oxygen, 0.5) and infused with Ringer's lactate (RL) solution (0.8 mL/kg per minute). Animals in group RL (n = 10) received no other interventions. Animals in group RL + LPS (n = 15) were infused with LPS (50 micrograms/kg) from a time range equal to 0 through 60 minutes. Animals in group RL + LPS + ibuprofen (n = 10) were similarly infused with LPS, but in addition, they received ibuprofen (10 mg/kg at -30 minutes and 10 mg/kg per hour from -30 through 210 minutes). Intestinal permeability was assessed by measuring plasma-to-lumen clearances of two hydrophilic probes (chromium 51-labeled edetic acid monohydrate [EDTA] and urea) and by expressing the results as a clearance ratio (CEDTA/CUREA). Survival was 100%, 67%, and 100% in groups RL, RL + LPS, and RL + LPS + ibuprofen, respectively. Among survivors only, CEDTA/CUREA increased significantly over time in both endotoxic groups, but not in nonendotoxic controls. Treatment with ibuprofen transiently blocked LPS-induced mesenteric hypoperfusion. These data indicate that mediators other than cyclooxygenase-derived metabolites of arachidonic acid are responsible for the adverse effect of LPS on mesenteric permeability to hydrophilic solutes in this porcine model.

Increased intestinal permeability in endotoxic pigs. Mesenteric hypoperfusion as an etiologic factor.

Infusing pigs with lipopolysaccharide (LPS) decreases superior mesenteric artery blood flow (Qsma), suggesting that mesenteric hypoperfusion may be responsible for LPS-induced alterations in gut mucosal permeability. To test this hypothesis, we studied four groups of anesthetized swine. Group 1 animals (N = 6) were infused with LPS (250 micrograms/kg over 1 hour beginning at 60 minutes) and continuously resuscitated with Ringer's lactate (48 mL/kg per hour). In group 2 (N = 5), Qsma was decreased by 50% by means of a mechanical occluder to mimic the LPS-induced alterations in Qsma observed in group I. Group 3 (N = 5) was included to document our ability to detect ischemia/reperfusion-induced alterations in mucosal permeability; in these pigs, Qsma was decreased in steps to zero flow (at 150 to 210 minutes) and then perfusion was restored (at 210 to 270 minutes). Pigs in group 4 (N = 6) served as normal controls; these animals were resuscitated with Ringer's lactate at the same rate as in group 1 but were not infused with LPS. To assess mucosal permeability, we measured plasma-to-lumen clearances for two markers, chromium 51-labeled edetic acid monohydrate (EDTA) and urea. Loading and maintenance infusions of the markers were given intravenously, and a 20-cm isolated segment of small intestine was continuously perfused at 2 mL/min with Ringer's lactate at 37 degrees C. Results were expressed as the ratio of the clearances for the two probes (CEDTA/CUREA). In group 3, CEDTA/CUREA was 999% +/- 355% of baseline at 270 minutes. In group 1, CEDTA/CUREA was 572% +/- 235% of baseline at 270 minutes. In groups 2 and 4, however, CEDTA/CUREA did not change significantly from the baseline value over the duration of the study. These data suggest that increased mucosal permeability after LPS is due to factors other than (or in addition to) mesenteric hypoperfusion.

Tropical splenomegaly syndrome in a nontropical setting.

Tropical splenomegaly syndrome, a rare complication of recurrent malarial infection thought to occur only in endemic areas, was diagnosed in a 9-year resident of the United States. The patient had splenomegaly, anemia, a history of recurrent fever since childhood, cryoglobulinemia, increased serum IgM, and elevated specific immunofluorescent antibody titers to Plasmodium falciparum. After antimalarial treatment and splenectomy, she became asymptomatic and the IgM levels and specific antibody titers returned to normal. Because of increased travel to and from endemic malarial areas, this syndrome should be considered in the differential diagnosis of chronic splenomegaly.

Familial clustering of mesothelioma: a report on three affected persons in one family.

Pleural mesothelioma developed in at least three members of a family of first-degree relatives. Only one member had probable direct asbestos exposure. An analysis of these cases and their circumstances leads us to suspect that a latent genetic susceptibility may be present in this cancer-prone family.

Acral keratoderma.

Three siblings displayed an unusual form of keratoderma characterized by diffuse and striate hyperkeratosis of the palms and soles, hyperkeratotic plaques over the dorsum of the hands and toes, and linear hyperkeratotic lesions over the Achilles tendon area, ankles, elbows, and knees. The predominant location of these lesions led to the term acral keratoderma for this disorder. Histologically, besides thickening of all epidermal layers with that of the stratum corneum being most notable, various dyskeratotic changes were evident in the epidermis. Pedigree analysis of the family suggested an autosomal recessive inheritance pattern. There were similarities and differences between the type of keratoderma displayed by these three patients and that of patients described previously with the disorder known as keratoma hereditarium mutilans.

Relationship between respiratory cancer and wetlands residency in Louisiana.

Cancer mortality is high among white men residing in southern Louisiana parishes (counties). In an effort to elucidate this phenomenon, we studied three environmental correlates of cancer-namely, smoking, residence in urban communities, and residence in the wetlands. Multiple regression analysis was applied to cancer mortalities adjusted for age and urban residency, and specific for race, sex, amount of standing water area in the parish, and cancer site. Cancer sites were grouped according to their correlation with smoking: strong, moderate, and no correlation. For men, the smoking-related cancer mortality not only showed an association with residence in wetlands but also was higher in the Louisiana wetlands than in the remainder of the United States.

Human longevity determinant genes.

Two recent major developments in the molecular biology of lower organisms point to genes as determinants of longevity. The first line of evidence is a selection system that established the participation of genes in aging and subsequently showed longevity to be a polygenic characteristic in Drosophila. The second validation of a genetic role in aging came from studies in which a mutation in an individual gene was found to modulate life span in nematodes. The achievements of genetics in the analysis of aging in mammals are less impressive than they have been for lower organisms, but this situation is changing. Although no genes have yet been directly implicated in prolonging life span in mammals, studies with mice have related immune function to longevity.

Evidence for a major gene effect in early-onset lung cancer.

Genetic segregation analyses that allowed for variable age of onset of lung cancer and smoking history were performed on 337 families, each ascertained through a lung cancer patient. Results indicated compatibility of the data with Mendelian codominant inheritance of a rare major autosomal gene that acts in concert with smoking to predispose carriers to lung cancer, by producing earlier onset of the cancer when controlling for equivalent smoking levels. Segregation at this locus could account for 69% and 47% of the cumulative incidence of lung cancer in individuals up to ages 50 and 60 respectively, but only 22% of all lung cancers in persons up to age 70. This decrease in the importance of the gene's contribution to overall lung cancer rates at later ages is most likely a reflection of an increasing proportion of noncarriers succumbing to the effects of long-term exposure to tobacco. A significant cohort effect was found, most likely due to differing smoking patterns before and after World War I, but in both cohorts the effect of a major locus could not be rejected.