Immunoglobulin- and hepatitis B surface antigen-specific circulating immune complexes in chronic hepatitis B virus infection

24 consecutive AIDS patients with wasting, and who had never received anabolic therapies, were evaluated to determine their profile of sex hormones and whether transformation of testosterone (T) to the nuclear androgen, dihydrotestosterone (DHT), was impaired. Eleven (46%) patients had normal testosterone and DHT (group I), 10 (42%) had normal testosterone but low DHT (group II), and 3 (12%) had low testosterone and low DHT (group III). Age, prior opportunistic complications, symptoms, serum albumin, hemoglobin levels, and CD4 lymphocyte counts were similar in the groups. DHT was significantly lower (22.2 +/- 6.8 microg/dl) in group II compared with group I (50.8 +/- 15.3 microg/dl). The ratio of T/DHT, a measure of the conversion of testosterone to DHT, in group I was 15.1 +/- 3.5, which was within the range for eugonadal young men. In group II, the ratio was 22.3 +/- 1.5, indicating a defect in generation of DHT. Patients in group II had lost 9.2 +/- 3.5 kg compared with 5.6 +/- 2.6 kg in group I (p = .015). Thus, a syndrome of low DHT with normal testosterone was associated with significantly greater weight loss than in patients with normal testosterone and DHT. Further studies are needed to clarify whether low DHT is a result of AIDS wasting or is causally related to weight loss and whether androgen therapy in the form of DHT could reverse some of the metabolic changes associated with AIDS wasting.     

Isolation and identification of the cDNA encoding the pheromone biosynthesis activating neuropeptide and additional neuropeptides in the oriental tobacco budworm, Helicoverpa assulta (Lepidoptera: Noctuidae)

The present study is concerned with cloning and characterizing Has-PBAN cDNA which is 756 nucleotides long, isolated from the brain and suboesophageal ganglion complex (Br-Sg) of Helicoverpa assulta adults. The 194-amino acid sequence deduced from this cDNA possessed the proteolytic endocleavage sites to generate multiple peptides. From the processing of the prepro-hormone, it can be predicted that the cDNA has a PBAN domain with 33 amino acids and four additional peptide domains: 24 amino acid-, 7 amino acid-, 18 amino acid- and 8 amino acid-long sequences, with FXPR (or K) L (X = G, T or S) amidated at their C-termini. The amino acid sequence of all five predicted peptides, including the PBAN, are identical to that of Helicoverpa zea (Raina, A.K., Jaffe, H., Kempe, T.G., Keim, P., Blacher, R.W., Fales, H.M., Riley, C.T., Klun, J.A., Ridgway, R.L., Hayes, D.K., 1989. Identification of a neuropeptide hormone that regulates sex pheromone production in female moths. Science 244, 796-798 and Ma, P.W.K., Knipple, D.C., Roelofs, W.L., 1994. Structural organization of the Helicoverpa zea gene encoding the precursor protein for pheromone biosynthesis-activating neuropeptide and other neuropeptides. Proc. Natl. Acad. Sci., U.S.A. 91, 506-510). A single mRNA species corresponding to the size of Has-PBAN cDNA was detected from the Br-Sg of 1-3-day old female and male adults, and their expression was also at a similar level. Pheromone production was induced upon injection of female or male Br-Sg extracts or synthetic PBAN into the haemocoel of decapitated 1-3-day old female adults during the photophase when they are not supposed to produce pheromone. From these results, H. assulta adult females seem to use their own PBAN for regulating sex pheromone biosynthesis. Functions of the four other peptides ending with FXPR (or K) L in the Has-PBAN cDNA and of the male PBAN remain to be elucidated.     

Genetic control of host resistance to flavivirus infection in animals

Flaviviruses are small, enveloped RNA viruses which are generally transmitted by arthropods to animals and man. Although flaviviruses cause important diseases in domestic animals and man, flaviviral infection of animals which constitute the normal vertebrate reservoir may be mild or sub-clinical, which suggests that some adaptation between virus and host may have occurred. While this possibility is difficult to study in wild animals, extensive studies using laboratory mice have demonstrated the existence of innate, flavivirus-specific resistance. Resistance is heritable and is attributable to the gene Flvr, which is located on chromosome 5 in this species. The mechanism of resistance is at present unknown, but acts early and limits the replication of flaviviruses in cells. While some evidence supports a role for Flvr in enhancing the production of defective interfering virus, thereby restricting the production of infectious virus, other reports suggest that Flvr interferes with either virus RNA replication or RNA packaging. Recent research suggests that cytoplasmic proteins bind to the viral replication complex and that allelic forms of these proteins in resistant mice may restrict the production of infectious progeny. Apparent resistance to flaviviruses has been described in other vertebrates, although it remains to be seen if this is attributable to a homologue of Flvr. Nonetheless, knowledge gained of the characteristics and function of Flvr in mice should be applicable to other host species, and improvement of resistance to flaviviral infection in domestic animals by selective breeding or gene technology may ultimately be possible.     

Induction of Bax-alpha precedes apoptosis in a human B lymphoma cell line: potential role of the bcl-2 gene family in surface IgM-mediated apoptosis

The members of the bcl-2 gene family are major regulators of programmed cell death, but their role in sIg-triggered apoptosis remains unclear. Using sensitive and resistant variants of the human B cell line BL-41, we studied the expression of the bcl-2 gene family during surface IgM-mediated apoptosis. We found constitutive Bcl-2 and Bcl-x expression, which remained unaltered after sIg cross-linking, in both resistant and sensitive cells. This and other experiments suggest that constitutive expression of Bcl-2 or Bcl-x alone is not sufficient to protect from activation-induced cell death in B cells. We therefore investigated Bax-alpha, the death-promoting splice variant of Bax, and found strong induction of both mRNA and protein upon sIg stimulation in sensitive cells. However, resistant subclones showed only weak expression, which was not inducible by sIg cross-linking. We provide evidence that up-regulation of Bax-alpha and the resulting imbalance of Bcl-2/Bax might be a major regulator of sIg-mediated apoptosis. Additionally, we found strong constitutive expression of Bcl-xs, the death promoting variant of Bcl-x, in sensitive cells, whereas resistant cells showed only weak Bcl-xs expression. Thus, we observed a much stronger expression of the death-promoting proteins Bax-alpha (inducible) and Bcl-xs (constitutive) in sensitive cells than in resistant cells. We therefore propose a potential role of the novel bcl-2 gene family members bcl-x and bax in surface IgM-triggered apoptosis.