Strongly baryon-dominated disk galaxies at the peak of galaxy formation ten billion years ago.

In the cold dark matter cosmology, the baryonic components of galaxies-stars and gas-are thought to be mixed with and embedded in non-baryonic and non-relativistic dark matter, which dominates the total mass of the galaxy and its dark-matter halo. In the local (low-redshift) Universe, the mass of dark matter within a galactic disk increases with disk radius, becoming appreciable and then dominant in the outer, baryonic regions of the disks of star-forming galaxies. This results in rotation velocities of the visible matter within the disk that are constant or increasing with disk radius-a hallmark of the dark-matter model. Comparisons between the dynamical mass, inferred from these velocities in rotational equilibrium, and the sum of the stellar and cold-gas mass at the peak epoch of galaxy formation ten billion years ago, inferred from ancillary data, suggest high baryon fractions in the inner, star-forming regions of the disks. Although this implied baryon fraction may be larger than in the local Universe, the systematic uncertainties (owing to the chosen stellar initial-mass function and the calibration of gas masses) render such comparisons inconclusive in terms of the mass of dark matter. Here we report rotation curves (showing rotation velocity as a function of disk radius) for the outer disks of six massive star-forming galaxies, and find that the rotation velocities are not constant, but decrease with radius. We propose that this trend arises because of a combination of two main factors: first, a large fraction of the massive high-redshift galaxy population was strongly baryon-dominated, with dark matter playing a smaller part than in the local Universe; and second, the large velocity dispersion in high-redshift disks introduces a substantial pressure term that leads to a decrease in rotation velocity with increasing radius. The effect of both factors appears to increase with redshift. Qualitatively, the observations suggest that baryons in the early (high-redshift) Universe efficiently condensed at the centres of dark-matter haloes when gas fractions were high and dark matter was less concentrated.

Risk of prostate cancer in African-American men: Evidence of mixed effects of dietary quercetin by serum vitamin D status.

BACKGROUND: African-American (AA) men experience higher rates of prostate cancer (PCa) and vitamin D (vitD) deficiency than white men. VitD is promoted for PCa prevention, but there is conflicting data on the association between vitD and PCa. We examined the association between serum vitD and dietary quercetin and their interaction with PCa risk in AA men. METHODS: Participants included 90 AA men with PCa undergoing treatment at Howard University Hospital (HUH) and 62 controls participating in HUH's free PCa screening program. We measured serum 25-hydroxy vitD [25(OH)D] and used the 98.2 item Block Brief 2000 Food Frequency Questionnaires to measure dietary intake of quercetin and other nutrients. Case and control groups were compared using a two-sample t-test for continuous risk factors and a Fisher exact test for categorical factors. Associations between risk factors and PCa risk were examined via age-adjusted logistic regression models. RESULTS: Interaction effects of dietary quercetin and serum vitD on PCa status were observed. AA men (age 40-70) with normal levels of serum vitD (>30 ng/ml) had a 71% lower risk of PCa compared to AA men with vitD deficiency (OR = 0.29, 95%CI: 0.08-1.03; P = 0.055). In individuals with vitD deficiency, increased dietary quercetin showed a tendency toward lower risk of PCa (OR = 0.91, 95%CI: 0.82-1.00; P = 0.054, age-adjusted) while men with normal vitD were at elevated risk (OR = 1.23, 95%CI: 1.04-1.45). CONCLUSION: These findings suggest that AA men who are at a higher risk of PCa may benefit more from vitD intake, and supplementation with dietary quercetin may increase the risk of PCa in AA men with normal vitD levels. Further studies with larger populations are needed to better understand the impact of the interaction between sera vitD levels and supplementation with quercetin on PCa in AA men.

High molecular gas fractions in normal massive star-forming galaxies in the young Universe.

Stars form from cold molecular interstellar gas. As this is relatively rare in the local Universe, galaxies like the Milky Way form only a few new stars per year. Typical massive galaxies in the distant Universe formed stars an order of magnitude more rapidly. Unless star formation was significantly more efficient, this difference suggests that young galaxies were much more molecular-gas rich. Molecular gas observations in the distant Universe have so far largely been restricted to very luminous, rare objects, including mergers and quasars, and accordingly we do not yet have a clear idea about the gas content of more normal (albeit massive) galaxies. Here we report the results of a survey of molecular gas in samples of typical massive-star-forming galaxies at mean redshifts of about 1.2 and 2.3, when the Universe was respectively 40% and 24% of its current age. Our measurements reveal that distant star forming galaxies were indeed gas rich, and that the star formation efficiency is not strongly dependent on cosmic epoch. The average fraction of cold gas relative to total galaxy baryonic mass at z = 2.3 and z = 1.2 is respectively about 44% and 34%, three to ten times higher than in today's massive spiral galaxies. The slow decrease between z approximately 2 and z approximately 1 probably requires a mechanism of semi-continuous replenishment of fresh gas to the young galaxies.

Metastatic choriocarcinoma presenting as a bleeding duodenal ulcer.

We report a case of a young man with a rare disease, a choriocarcinoma of the gastrointestinal tract presenting as a common entity, a bleeding duodenal ulcer. Pathological findings and strongly positive immunostains of tissue specimens for beta human chorionic gonadotrophin confirmed the entire tumor to be a choriocarcinoma ruling out the possibility of an adenocarcinoma with focal components of choriocarcinoma or a beta human chorionic gonadotrophin producing adenocarcinoma. The pattern of tumor invasion in this case is more suggestive of metastatic than primary involvement of the gastrointestinal tract. The diagnosis of primary gastrointestinal choriocarcinoma is difficult because of the need to meticulously rule out the occurrence of a primary in other organs, which at times regresses spontaneously, a diagnosis made more difficult in this case in which no autopsy was performed.

A method for establishing primary cultures of human gastric epithelial cells.

Long-term culture of human gastric epithelial cells has been difficult, and at present no normal human gastric epithelial cell lines are readily available. As part of our experiments to study pathogenesis of H. pylori, a bacterium that infects the stomach, we developed methods to culture normal human gastric epithelial cells. Primary cultures of human gastric epithelial cells can be established from gastric biopsies taken at upper G.I. endoscopy. Enzymatically isolated gastric epithelial-like cells are present in tight colonies on culture dishes within 24 hours of placing the cells in culture. Cells isolated stain positively for cytokeratin and produce neutral mucins, indicating that they are mucin secreting epithelial cells, consistent with gastric epithelial cells. Epithelial cells can be maintained up to 4 weeks in culture with evidence of DNA synthesis up through the first week of culture.

Testicular plasmacytoma in a patient with the acquired immunodeficiency syndrome.

Clinical, laboratory, and pathologic findings from a case of primary extramedullary plasmacytoma of the testis and sinuses in a patient with acquired immunodeficiency syndrome (AIDS) are presented. To our knowledge this is the first case in the English literature of a primary testicular plasmacytoma in an HIV-infected patient. The findings in this report and those of others confirm the difference in the pattern of plasma cell tumor (PCT) presentation in patients infected with AIDS from those in non-infected individuals, suggesting that these tumors should be considered in the differential diagnosis of AIDS-associated malignancies.

Effects of Helicobacter pylori on proliferation of gastric epithelial cells in vitro.

OBJECTIVE: H. pylori infection of the gastric mucosa has been associated with an increase in gastric epithelial cell proliferation. However, in vitro adherence of H. pylori to gastric epithelial cells is associated with reduced cell proliferation. Reduction of epithelial cell proliferation may contribute to ulcer formation and delay ulcer healing. The following study was undertaken to elucidate the ability of cagA-positive and -negative strains to impede gastric epithelial cell proliferation. METHODS: A human gastric adenocarcinoma cell line (AGS) was overlaid with either cagA-positive or cagA-negative H. pylori strains suspended in cell culture medium. Proliferation of AGS cells was analyzed by performing direct cell counts and by measuring metabolism of a soluble tetrazolium compound (MTS), after exposure to H. pylori for 24 h. RESULTS: When compared with control cells cultured in medium alone, AGS cell proliferation was reduced by 45.6% and 28.5% due to exposure to cagA-negative and cagA-positive strains, respectively. When bacterial-induced cytotoxicity was assessed by measuring release of lactose dehydrogenase (LDH) into the culture medium, cagA-positive strains were shown to induce significantly more cytotoxicity than cagA-negative strains. CONCLUSIONS: These experiments demonstrate that H. pylori exposure to AGS cells significantly reduces cell proliferation. However, cagA-positive strains that induce more cell injury reduce cell proliferation to a lesser extent than cagA-negative strains. Persistent replication of gastric epithelial cells injured by exposure to cagA-positive strains may be partially responsible for the stronger association with gastric cancer in persons infected with cagA-positive H. pylori strains.

Increased incidence of second primary malignancy in patients with carcinoid tumors: case report and literature review.

There is an increased incidence of second noncarcinoid neoplasms in patients with carcinoid tumors. This article reports a case of a synchronous malignant ileal carcinoid tumor in a patient with an adenocarcinoma of the sigmoid colon. This report illustrates the increased association of carcinoid tumors with other gastrointestinal malignancies.

Effects of sucralfate on vacuolating cytotoxin activity and adherence of Helicobacter pylori to human gastric epithelial cells.

Sucralfate inhibits activity of certain Helicobacter pylori enzymes, implying that this medication may limit gastric cell injury associated with H pylori infection. This study evaluates the ability of sucralfate and its two major structural components, sucrose octasulfate and aluminum hydroxide, to reduce the cytotoxic effects of H pylori and to inhibit binding of H pylori to human gastric epithelial cells. Experiments were performed using human gastric epithelial cells isolated from gastric biopsy tissue taken at upper gastrointestinal endoscopy. Primary cultures of human gastric epithelial cells, when exposed to broth-culture supernatant from a vacuolating cytotoxin-positive H pylori strain, were shown to form cytoplasmic vacuoles. Preexposing H pylori brothculture supernatant to sucralfate reduced vacuole formation in human gastric epithelial cells; however, preexposure of H pylori broth-culture supernatant to aluminum hydroxide or sucrose octasulfate did not reduce vacuolation in human gastric epithelial cells. H pylori binding to human gastric epithelial cells was significantly reduced when H pylori was exposed to sucralfate prior to incubating the bacterium with human gastric epithelial cells. These data show that sucralfate, but not its two major components, reduces the toxicity of an H pylori-produced cytotoxin (VacA) and decreases H pylori adherence to human gastric epithelial cells. This reduction in H pylori cytotoxicity may contribute to sucralfate's ulcerhealing properties and to the lower ulcer recurrence rates seen in patients treated with this medication.

Adherence of Helicobacter pylori to cultured human gastric epithelial cells.

Experiments were performed to demonstrate that adherence of Helicobacter pylori to gastric epithelial cells causes alterations in the cell cytoskeleton. H. pylori intimately attached to cultured human gastric epithelial cells on small cellular projections, while there was no intimate association of H. pylori with cultured human esophageal epithelial cells. Fluorescein-conjugated phalloidin staining of gastric epithelial cells showed that H. pylori adherence stimulated actin polymerization; this stimulation was not observed with esophageal cells. Also, this organism's selectivity for gastric mucosa was supported by rare binding of bacteria to esophageal epithelial cells and gastric fibroblasts.

Intrapulmonary thymoma.

A 50-year-old man presented with a lung mass in the left upper lobe, which was shown by electron microscopy to be a thymoma. There was no evidence of a mediastinal mass. The lymphocytes of the tumor reacted with monoclonal antibody T101, a pan T-cell marker, and with OKT8. B1 and B2 surface antigens characteristic of B lymphocytes were not detected. Tumors of thymic epithelial cells completely covered by pleura without mediastinal involvement are rare.

Infectious crystalline keratopathy.

In three patients (three men, 44, 67, and 83 years old) an unusual keratopathy characterized by white, branching, crystalline stromal opacities produced lesions that were insidious, that increased in size slowly, and that were clinically and histopathologically associated with little corneal inflammation. Intraocular inflammation eventually became evident in two of the patients. The keratopathy developed while the patients were using topical corticosteroids. In two cases, histopathologic studies disclosed accumulations of gram-positive cocci in the corneal stroma; a viridans streptococcus agent was isolated on culture. In one case, the viridans streptococcus was determined to be a dextran producer, which may have contributed to the pathogenesis of the keratopathy. Despite aggressive treatment with a variety of drugs, epithelial healing, and resolution of the corneal infiltrate, residual scarring persisted in two cases and neovascularization and graft edema in one case each.