Does aspartic acid racemization constrain the depth limit of the subsurface biosphere?

Previous studies of the subsurface biosphere have deduced average cellular doubling times of hundreds to thousands of years based upon geochemical models. We have directly constrained the in situ average cellular protein turnover or doubling times for metabolically active micro-organisms based on cellular amino acid abundances, D/L values of cellular aspartic acid, and the in vivo aspartic acid racemization rate. Application of this method to planktonic microbial communities collected from deep fractures in South Africa yielded maximum cellular amino acid turnover times of ~89 years for 1 km depth and 27 °C and 1-2 years for 3 km depth and 54 °C. The latter turnover times are much shorter than previously estimated cellular turnover times based upon geochemical arguments. The aspartic acid racemization rate at higher temperatures yields cellular protein doubling times that are consistent with the survival times of hyperthermophilic strains and predicts that at temperatures of 85 °C, cells must replace proteins every couple of days to maintain enzymatic activity. Such a high maintenance requirement may be the principal limit on the abundance of living micro-organisms in the deep, hot subsurface biosphere, as well as a potential limit on their activity. The measurement of the D/L of aspartic acid in biological samples is a potentially powerful tool for deep, fractured continental and oceanic crustal settings where geochemical models of carbon turnover times are poorly constrained. Experimental observations on the racemization rates of aspartic acid in living thermophiles and hyperthermophiles could test this hypothesis. The development of corrections for cell wall peptides and spores will be required, however, to improve the accuracy of these estimates for environmental samples.

Coupling hydrocarbon degradation to anaerobic respiration and mineral diagenesis: theoretical constraints.

The diagenetic mineral assemblages in petroleum reservoirs control the formation fluid pH and pCO(2). Anaerobic biodegradation of petroleum is controlled by the transfer of electrons from reduced organic species to inorganic, redox sensitive, aqueous and mineral species in many cases through intermediates such as H(2) and CH(3)COO(-). The terminal electron accepting reactions induce the dissolution or precipitation of the same minerals that control the ambient pH and pCO(2) in petroleum reservoirs. In this study, we develop a model for anaerobic biodegradation of petroleum that couples the production of acetate and H(2) to 'late stage' diagenetic reactions. The model reveals that the principal terminal electron accepting process and electron donor control the type of diagenetic reaction, and that the petroleum biodegradation rate is controlled through thermodynamic restriction by the minimum DeltaG required to support a specific microbial metabolism, the fluid flux and the mineral assemblage. These relationships are illustrated by modeling coupled microbial diagenesis and biodegradation of the Gullfaks oil reservoir. The results indicate that the complete dissolution of albite by acids generated during oil biodegradation and the corresponding elevated pCO(2) seen in the Gullfaks field are best explained by methanogenic respiration coupled to hydrocarbon degradation and that the biodegradation rate is likely controlled by the pCH(4). Biodegradation of Gullfaks oil by a consortium that includes either Fe(3+)-reducing or -reducing bacteria cannot explain the observed diagenetic mineral assemblage or pCO(2). For octane, biodegradation, not water washing, was the principal agent for removal at fluid velocities <20 m Myr(-1).

AIDS-related services and training in outpatient mental health care agencies in New York.

Directors of 471 outpatient mental health settings in New York State (82.1 percent of 574 settings located in counties with intermediate to high AIDS case rates) completed a survey about HIV and AIDS services, training needs, and barriers to care. Most of the sites served one to ten persons with HIV infection annually and had staff members who were trained in providing at least one HIV-related service. Nonetheless, 84 percent of the respondents reported unmet needs for training. The likelihood of providing certain services was significantly increased in sites that were in urban locations, primarily served clients with comorbid alcohol or other drug use disorders, lacked funds for providing condoms, had staff members who were trained in HIV and AIDS services, identified particular HIV training needs, believed clients needed condoms, and viewed HIV-related services as very important.

Resolution of spur cell anemia with liver transplantation: a case report and review of the literature.

Spur cell anemia is an acquired hemolytic anemia, characterized by an increased percentage of abnormally shaped erythrocytes that are known as acanthocytes. The erythrocytes have numerous spicules irregularly distributed over the cell surface. Spur cell anemia has been described to occur in several conditions, including cirrhosis. We present an unusual case of a young patient with hemochromatosis, alcohol abuse, decompensated cirrhosis, and spur cell anemia who had a spontaneous resolution of the spur cell anemia after orthotopic liver transplantation. This finding suggests that the diseased liver may contribute to transformation of the erythrocyte to the spur cell.

Suppression of TNF-alpha gene expression by hemin: implications for the role of iron homeostasis in host inflammatory responses.

Tumor necrosis factor alpha (TNF-alpha) has multiple effects on iron homeostasis and erythropoiesis and has been implicated in the pathogenesis of the anemia of inflammation. We postulated that intracellular iron in turn may regulate the expression of TNF-alpha. In the human monocytic leukemia cell line, THP-1, low basal TNF-alpha message levels were stimulated (sevenfold) when serum was excluded from the culture medium. Addition of hemin completely suppressed TNF-alpha expression. Similarly, hemin suppressed lipopolysaccharide-induced expression of TNF-alpha. Sn-protoporphyrin, an inhibitor of heme oxygenase (which releases iron from hemin), prevented hemin-induced suppression of TNF-alpha expression. Conversely, the intracellular iron chelator, desferrioxamine, stimulated TNF-alpha expression. Thus, the expression of TNF-alpha, itself a physiological regulator of iron homeostasis, appears to be controlled by intracellular levels of iron.

Breast-conserving therapy for stage I-II synchronous bilateral breast carcinoma.

BACKGROUND: Synchronous bilateral breast carcinoma (SBBC) is an uncommon presentation, and the management of patients with this disease is not well established. METHODS: In order to evaluate whether patients with early-stage SBBC could be safely and effectively treated with bilateral breast-conserving therapy (BCT), the authors retrospectively reviewed the records of 24 patients with clinical Stage I-II SBBC treated during the period 1977-1989 with bilateral BCT. SBBC was defined as bilateral invasive carcinomas diagnosed no more than 1 month apart. The median age at diagnosis was 56 years (range, 32-85 years), and the median follow-up for surviving patients was 95 months (range, 68-157 months). Pathology slides were available for review in 19 cases. Cosmetic results and complications after BCT were scored. Outcome was compared with that of 1314 patients with unilateral Stage I or II breast carcinoma, within the same age range, treated during the same time period. RESULTS: There were no significant differences between the SBBC and unilateral groups in actuarial disease free survival (70% and 74%, respectively, at 5 years), overall survival (88% and 87%, respectively, at 5 years), or crude distribution of sites of first failure. Multivariate analysis of overall survival and disease free survival also did not show bilaterality to be a significant factor. The cosmetic results for the SBBC group were not significantly different from those for the unilateral group. Physician assessment of cosmetic outcome was excellent in 57% and good in 43% of SBBC patients evaluated 25-48 months after BCT. Long term complications were rare in both groups. CONCLUSIONS: Patients with early-stage SBBC can be safely treated with carefully planned, bilateral BCT, with outcome that appears to be comparable to that of patients with early-stage unilateral breast carcinoma.

Platelet-derived growth factor in human malignancy.

Platelet-derived growth factor (PDGF) was first implicated in the process of transformation when one of its peptide chains was found to be homologous to the viral sis oncogene (v-sis). Since that time, there have been multiple demonstrations of the transforming activity of v-sis in fibroblasts. Because of the near identity of the v-sis protein with the PDGF B chain, v-sis is thought to transform through an autocrine stimulatory mechanism of cell growth. Consistent with this view are studies which demonstrate inhibition of v-sis-mediated transformation by anti-PDGF antibodies. Expression of the cellular sis gene (c-sis) and its receptors, and secretion of PDGF-like factors have been demonstrated in many types of human malignant cells. Nevertheless, a causative role for c-sis in inducing or maintaining the transformed phenotype in human malignancies remains to be established. There are significant differences in structure between v-sis and c-sis. Studies of transforming ability have yielded conflicting results in transfection models, depending on the transfected vector and target cell type utilized. While there is compelling evidence for the involvement of PDGF in an autocrine growth mechanism in transformed fibroblasts, the evidence in human epithelial tumor types is less convincing because PDGF receptors are usually not detectable on the cell surface. The recent demonstration of intracellular co-localization of active PDGF precursors and PDGF receptors, however, supports the existence of an internal autocrine pathway independent of PDGF secretion. Further investigation of such a mechanism in de novo human malignancies is warranted to establish the role of PDGF in the development of these neoplasms.

Radiation therapy of seminoma: 17-year experience at the Joint Center for Radiation Therapy.

One hundred and sixteen patients with stage I and II primary testicular seminoma were treated at the Joint Center for Radiation Therapy (JCRT) between 1968 and 1984. Complete follow-up is available for 114 patients (98%) with a median follow-up time of 6 years. Actuarial relapse-free survival (RFS) and survival for the entire group at 10 years were 94 and 86%, respectively, with 27 patients still at risk beyond 10 years. Actuarial RFS and survival at 10 years by stage were 97 and 92% for stage I, 93 and 81% for stage IIa, 100 and 100% for stage IIb, but only 75 and 51% for stage IIc. The difference in actuarial survival between stage IIc patients and stage I, IIa and IIb patients was significant (p less than 0.01). These results indicate that radiation therapy is excellent treatment for stage I and II seminomas as long as the largest mass of disease is not greater than 5 cm (stage IIc). Patients with stage IIc seminoma are now treated with cisplatin-containing combination chemotherapy followed by radiation therapy to areas of bulk disease. Although the majority of patients with stage II disease in this series received mediastinal irradiation, this is no longer recommended at the JCRT.

Platelet-derived growth factor synthesis in mesangial cells: induction by multiple peptide mitogens.

Platelet-derived growth factor (PDGF) has been implicated in several nonmalignant pathophysiological processes, including proliferative diseases of the kidney. Glomerular mesangial cells secrete a PDGF-like factor and express the PDGF A-chain and c-sis (or B-chain) mRNAs. We report here that both mRNAs are induced by serum and this effect can be mimicked by recombinant PDGF, which also markedly stimulates DNA synthesis. Other growth factors, such as epidermal growth factor (EGF), transforming growth factor type alpha, basic fibroblast growth factor (bFGF), and tumor necrosis factor type alpha (TNF-alpha) also are mitogenic for human mesangial cells and induce expression of the PDGF mRNAs. EGF, TNF-alpha, and bFGF also stimulate these cells to secrete a PDGF-like factor. Furthermore, anti-PDGF antibody partially abrogates the mitogenic effect of EGF, suggesting that mitogen-stimulated PDGF synthesis in mesangial cells is at least partly responsible for cell growth induced by other growth factors. In contrast to these results, transforming growth factor type beta (TGF-beta), while inducing both mRNAs, is not mitogenic, indicating that its effect on message levels can be dissociated from DNA synthesis. These data suggest that several peptide growth factors regulate the growth of mesangial cells and that PDGF may be an effector molecule that plays a role in the mitogenic response to many of these growth stimuli.

Mesangial cells express PDGF mRNAs and proliferate in response to PDGF.

Platelet-derived growth factor (PDGF) is a potent mitogen for cells of mesenchymal origin and is released and/or synthesized by platelets, macrophages, endothelial cells, and rat mesangial cells. In the present investigation, we found that human glomerular mesangial cells in culture release a PDGF-like protein which competes for 125I-PDGF binding to human foreskin fibroblasts and is mitogenic for these fibroblasts. The competing and to a lesser extent the mitogenic activities present in the conditioned medium are partially recognized by an anti-PDGF antibody. Northern blot analysis of poly(A)+ RNA from human mesangial cells demonstrates the expression of both PDGF A- and B-chain mRNAs. PDGF also binds to mesangial cells in a specific manner and stimulates DNA synthesis and cell proliferation. These data suggest that a PDGF-like protein secreted by mesangial cells or released from platelets, monocytes, or endothelial cells during glomerular inflammation may function as an autocrine or a paracrine growth factor for these cells. The biological role of PDGF in mediating proliferative and other inflammatory events in the glomerulus remains to be identified.

Cyclic AMP regulation of the human glycoprotein hormone alpha-subunit gene is mediated by an 18-base-pair element.

cAMP regulates transcription of the gene encoding the alpha-subunit of human chorionic gonadotropin (hCG) in choriocarcinoma cells (BeWo). To define the sequences required for regulation by cAMP, we inserted fragments from the 5' flanking region of the alpha-subunit gene into a test vector containing the simian virus 40 early promoter (devoid of its enhancer) linked to the bacterial chloramphenicol acetyltransferase (CAT) gene. Results from transient expression assays in BeWo cells indicated that a 1500-base-pair (bp) fragment conferred cAMP responsiveness on the CAT gene regardless of position or orientation of the insert relative to the viral promoter. A subfragment extending from position -169 to position -100 had the same effect on cAMP-induced expression. Furthermore, the entire stimulatory effect could be achieved with an 18-bp synthetic oligodeoxynucleotide corresponding to a direct repeat between positions -146 and -111. In the absence of cAMP, the alpha-subunit 5' flanking sequence also enhanced transcription from the simian virus 40 early promoter. We localized this enhancer activity to the same -169/-100 fragment containing the cAMP response element. The 18-bp element alone, however, had no effect on basal expression. Thus, this short DNA sequence serves as a cAMP response element and also functions independently of other promoter-regulatory elements located in the 5' flanking sequence of the alpha-subunit gene.

Coordinate regulation of the messenger ribonucleic acids encoding the alpha- and beta-subunits of human chorionic gonadotropin in HeLa cells and butyrate-resistant variants.

Short term exposure of HeLa S3 cells to sodium butyrate induces accumulation of the mRNAs encoding both the alpha- and beta-subunits of hCG. Both mRNAs accumulate with the same kinetics and reach maximal levels with the same concentration of butyrate, suggesting that the levels of alpha and hCG beta mRNAs are coordinately regulated. In addition, induction of both mRNAs is tightly coupled with a similar increase in secreted levels of hCG subunit protein, further suggesting that regulation of CG biosynthesis in HeLa cells occurs before translation. To determine whether HeLa cells which have overcome the growth inhibitory properties of butyrate show uniformly high levels of alpha and hCG beta mRNAs, we isolated clonal variants by stepwise selection with increasing concentrations of butyrate. Of 69 isolated variants, at least 2 (AO and B2) display different patterns of CG gene expression. In AO cells, alpha-subunit mRNA was not detectable, while in B2 cells, the level of alpha-subunit mRNA was similar to that of wild-type HeLa S3 cells. Conversely, hCG beta mRNA levels in both variant cell lines approximated levels found in butyrate-treated HeLa S3 cultures, suggesting that the mRNAs for alpha and hCG beta are regulated independently. Analysis of genomic DNA by blot hybridization indicated that the alpha-subunit gene was present as a single unrearranged copy in HeLa S3 cells and in both variants, indicating that differences in alpha-subunit gene expression are not associated with major genomic alterations, but probably reflect more subtle changes.

The gene for the beta subunit of bovine luteinizing hormone encodes a gonadotropin mRNA with an unusually short 5'-untranslated region.

Both cDNA and genomic clones encoding the beta subunit of bovine luteinizing hormone (LH) have been isolated and characterized. The nucleotide sequence was determined for the entire gene and 776 base pairs of 5'-flanking sequence. The mRNA cap site and polyadenylation site were mapped by primer extension and S1 nuclease protection, respectively. The bovine LH beta spans less than 1.1 kilobase pairs and has three exons encoding a 550 nucleotide mRNA (excluding the poly(A) tail). Bovine LH beta is a single-copy gene, in contrast to human LH beta, which is a member of the LH/chorionic gonadotropin beta subunit multigene family. Comparison of the bovine LH beta gene with the human LH beta/chorionic gonadotropin gene family reveals a high degree of nucleotide sequence homology, both within the genes and in the 5'-flanking sequences. Despite this extensive sequence conservation, there is a major difference between the two species in the selection of a promoter site. As a result, the bovine LH beta gene produces an mRNA with an usually short 5'-untranslated region of only 6-11 nucleotides.

The Cuban immigration of 1980: a special mental health challenge.

The 124,769 Cubans who entered the United States from Cuba in a boatlift in 1980 included a small minority of people who needed mental health care. Some had been taken involuntarily from psychiatric hospitals, mental retardation facilities, jails, and prisons. The National Institute of Mental Health, Public Health Service (PHS), was responsible for mental health screening, evaluation, and treatment of the Cuban Entrants. Bilingual psychiatrists and psychologists found that many Entrants given preliminary evaluations showed evidence of transient situational stress reactions, not psychiatric illnesses. Entrants who had not yet been sponsored were consolidated into one facility in October 1980, and about 100 of those with severe problems were transferred to an Immigration and Naturalization Service-PHS evaluation facility in Washington, DC. Between March 1, 1981, and March 1, 1982, a total of 3,035 Entrants were evaluated at both facilities. Among the 1,307 persons who presented symptoms, there was a primary diagnosis of personality disorders for 26 percent, schizophrenic disorders for 15 percent, adjustment disorders for 14.5 percent, mental retardation for 8.6 percent, chronic alcohol abuse for 8.6 percent, and major depression for 7.2 percent. Only 459 Cubans with symptoms were found to be in need of further psychiatric care. As of October 1984, many Entrants with psychiatric illnesses remained under inpatient or community-based halfway house psychiatric care as a direct Federal responsibility. A PHS program for further placement in community-based facilities is underway.

The 1990 objectives for the nation for control of stress and violent behavior: progress report.

The control of stress and violent behavior is 1 of the 15 priority areas addressed in the Public Health Service's Objectives for the Nation. The National Institute of Mental Health, which provides a national focus for the Federal effort to increase knowledge of, and promote effective strategies dealing with, issues associated with mental illness and mental health, has been designated the lead Federal agency in this priority area. The authors summarize progress achieved and further activities planned with respect to 10 objectives for control of stress and violent behavior that have been selected for Federal implementation. The objectives for control of stress include improved public and professional awareness of community agencies that can provide professional services, hotlines, and mutual support groups. The objectives for control of violent behavior address three major problems: deaths from homicide among young black males, suicide among the young, and child abuse. Achievement of several of the objectives is currently impeded by lack of a valid data base. Efforts have been initiated, both by individual agencies and through collaboration among the various participating Public Health Service components, to develop valid and reliable baseline data and surveillance procedures.

Choriocarcinoma, thyrotoxicosis, and the Klinefelter syndrome.

A patient with the combined features of Klinefelter syndrome, thyrotoxicosis and a primary mediastinal choriocarcinoma is reported. Review of the literature reveals that extragonadal germ cell tumors appear to be significantly associated with the Klinefelter syndrome. The reason for this is presently unclear but may involve an unusual propensity of the extragonadal aneuploid germ cell to undergo malignant degeneration.