Mutations in SOX2 cause anophthalmia-esophageal-genital (AEG) syndrome

Table 1     

Physiological factors influencing radioantibody uptake: a study of four human colonic carcinomas.

We evaluated the accretion of 131I-labeled NP-4 anticarcinoembryonic antigen (CEA) into 4 size-matched human colonic carcinomas grown s.c. in nude mice. Antibody uptake for LS174T and GW-39 tumors was relatively high (19 to 23% ID/g on day 3), whereas moderate uptake was seen in the Moser tumor (7.5% on day 3) and low uptake was detected in the GS-2 tumor (1.8% on day 3). Blood clearance of radioantibody was twice as fast in mice with GS-2 tumors than in mice with GW-39, LS174T or Moser tumors. Seven physiological parameters that might influence radioantibody accretion were evaluated in order to better understand the differences in observed tumor targeting: vascular volume, blood flow rate, vascular permeability, tumor antigen content, serum antigen content and complexation of radioantibody, intratumoral antigen distribution, and intracellular antigen distribution. Although marked variability in vascular physiology, antigen content and antibody complexation of the 4 tumors grown in the same host and site existed, it was insufficient to explain the differences in antibody uptake. However, intra-tumoral distribution of antigen, and sub-cellular accessibility of antigen for radioantibody were important considerations. GS-2 tumors are well differentiated and have polarized cells. CEA in GS-2 is largely inaccessible to radioantibody; most of the antigen is located in the lumen of the glands or on the apical surface of gland cells and most of the antibody distributes to the stromal region on the basolateral surface. The low antibody targeting in GS-2 could therefore be explained by restricted intra-tumor accessibility of antibody. Scatchard analysis of NP-4 binding to Moser cells under non-internalizing and internalizing conditions revealed that 90% of the antigen is found within the cell, unavailable to bind with the NP-4 antibody, which is slow to internalize. In contrast, CEA in LS174T cells was almost entirely accessible. The reduced antibody targeting to Moser xenografts might therefore, be explained by restricted antibody accessibility at the cellular level.     

Comparison of amphotericin B with fluconazole in the treatment of acute AIDS-associated cryptococcal meningitis. The NIAID Mycoses Study Group and the AIDS Clinical Trials Group.

BACKGROUND. Intravenous amphotericin B, with or without flucytosine, is usually standard therapy for cryptococcal meningitis in patients with the acquired immunodeficiency syndrome (AIDS). Fluconazole, an oral triazole agent, represents a promising new approach to the treatment of cryptococcal disease. METHODS. In a randomized multicenter trial, we compared intravenous amphotericin B with oral fluconazole as primary therapy for AIDS-associated acute cryptococcal meningitis. Eligible patients, in all of whom the diagnosis had been confirmed by culture, were randomly assigned in a 2:1 ratio to receive either fluconazole (200 mg per day) or amphotericin B. Treatment was considered successful if the patient had had two consecutive negative cerebrospinal fluid cultures by the end of the 10-week treatment period. RESULTS. Of the 194 eligible patients, 131 received fluconazole and 63 received amphotericin B (mean daily dose, 0.4 mg per kilogram of body weight in patients with successful treatment and 0.5 mg per kilogram in patients with treatment failure; P = 0.34). Treatment was successful in 25 of the 63 amphotericin B recipients (40 percent; 95 percent confidence interval, 26 percent to 53 percent) and in 44 of the 131 fluconazole recipients (34 percent; 95 percent confidence interval, 25 percent to 42 percent) (P = 0.40). There was no significant difference between the groups in overall mortality due to cryptococcosis (amphotericin vs. fluconazole, 9 of 63 [14 percent] vs. 24 of 131 [18 percent]; P = 0.48); however, mortality during the first two weeks of therapy was higher in the fluconazole group (15 percent vs. 8 percent; P = 0.25). The median length of time to the first negative cerebrospinal fluid culture was 42 days (95 percent confidence interval, 28 to 71) in the amphotericin B group and 64 days (95 percent confidence interval, 53 to 67) in the fluconazole group (P = 0.25). Multivariate analyses identified abnormal mental status (lethargy, somnolence, or obtundation) as the most important predictive factor of a high risk of death during therapy (P less than 0.0001). CONCLUSIONS. Fluconazole is an effective alternative to amphotericin B as primary treatment of cryptococcal meningitis in patients with AIDS. Single-drug therapy with either drug is most effective in patients who are at low risk for treatment failure. The optimal therapy for patients at high risk remains to be determined.     

The source and action of histamine in the isolated guinea-pig gallbladder

We have investigated the effects of histamine on motility of the gallbladder and characterized the receptor types involved. Histamine and the histamine H₁-receptor agonist, 2-thiazolylethylamine (2-TEA) contracted the isolated guinea-pig gallbladder strip in a dose dependent manner. The contractile response to histamine was shifted to the right by the H₁-receptor antagonist, mepyramine. In pre-contracted gallbladder strips, the H₂-receptor agonist dimaprit reduced the tension generated in a dose dependent fashion. The histamine H₂-receptor antagonist, ranitidine shifted the histamine concentration effect curve to the left and attenuated the dose dependent relaxations elicited at high concentrations. The histamine H₃-receptor agonist, (R)--methylhistamine (RMHA) elicited dose dependent contraction of the tissue which was significantly inhibited in the presence of mepyramine. The effects of electrical field stimulation (EFS) on the strips were not significantly altered by the presence of RMHA (10^–10–10^–7 M) indicating little pre-synaptic H₃ activity in this tissue. Histamine immunoreactivity (IR) was detected in gallbladder whole mount preparations of the mucosa and the muscularis/serosa. The histamine IR appeared cell bound in cells of varying morphological characteristics but no IR was detected in nerve fibres or cell bodies (ganglia). Alcian blue staining was consistent with the distribution of histamine IR cells as mast cells. The results indicate that histamine is distributed in the guinea-pig gallbladder and it can regulate contractile activity via activation of H₁ and H₂ but not H₃ receptors.     

Reduced virulence of HWP1-deficient mutants of Candida albicans and their interactions with host cells

The Candida albicans gene HWP1 encodes a surface protein that is required for normal hyphal development in vitro. We used mutants lacking one or both alleles of HWP1 to investigate the role of this gene in virulence. Mice infected intravenously with the homozygous hwp1 null mutant, CAL3, survived a median of >14 days, whereas mice infected with a control strain containing two functional alleles of HWP1 survived only 3.5 days. After 1 day of infection, all strains produced similar levels of infection in the kidneys, spleen, and blood. However, after 2 and 3 days, there was a significant decrease in the number of organisms in the kidneys of the mice infected with CAL3. This finding suggests that the hwp1 homozygous null mutant is normal in its ability to initiate infection but deficient in its capacity to maintain infection. CAL3 also germinated minimally in the kidneys. The ability of the heterozygous null mutant to germinate and cause mortality in mice was intermediate to CAL3, suggesting a gene dosage effect. To investigate potential mechanisms for the diminished virulence of CAL3, we examined its interactions with endothelial cells and neutrophils in vitro. CAL3 caused less endothelial cell injury than the heterozygous hwp1 mutant. We conclude that the HWP1 gene product is important for both in vivo hyphal development and pathogenicity of C. albicans. Also, the ability to form filaments may be critical for candidal virulence by enabling the fungus to induce cellular injury and maintain a deep-seated infection.     

Molecular studies of trophoblast HLA-G: polymorphism, isoforms, imprinting and expression in preimplantation embryo

There is considerable interest in human HLA-G arising from the observation that it is expressed selectively on the surface of extravillous trophoblast, the fetal cell population directly in contact with the mother. We investigated several aspects of the molecular biology of this unusual molecule. Limited polymorphism at the nucleotide level, and even more restricted variation at the amino acid level, was found in our Caucasian population. A further unusual aspect of HLA-G is the occurrence of alternatively spliced mRNAs. Spliced messages that could give rise to either membrane-bound or soluble proteins have been reported and six of these alternative forms were detected in all first trimester and term placentae, highly purified villous and extravillous trophoblast and the cell lines, JEG-3 and 221-G. An additional novel splice variant involving loss of part of the 3'-untranslated region was observed with two alleles. Using a sensitive RNase protection assay higher levels of the membrane-bound RNAs as compared to the soluble forms were detected in first trimester and term placentae as well as in JEG-3. Contrary to previous findings our term samples taken from the maternal aspect showed higher levels of both mRNA species when compared to first trimester placenta. The question of imprinting was addressed through the detection of heterozygotes both in placental tissue and, more tellingly, in the purified trophoblast cells. There was no evidence of imprinting. In addition we did not find mRNA for HLA-G in human two to eight-cell embryos or in blastocyst or in sperm samples.