Studies of the Sal I strain of Plasmodium vivax in the squirrel monkey (Saimiri sciureus)

The Sal I strain of Plasmodium vivax was successfully adapted to three phenotypes of the squirrel monkey, Saimiri sciureus. Through five linear blood passages, parasitemias in excess of 200,000/mm3 blood were attained; Bolivian phenotype Saimiri appear to develop higher peak parasitemias. Sporozoites of the Sal I strain inoculated intravenously produced patent parasitemias in all five squirrel monkeys challenged, with prepatent periods ranging from 21 to 38 days. Anopheles freeborni and An. gambiae were the most susceptible of eight anopheline species fed on infected squirrel monkeys. As a model for in vivo studies of P. vivax the Sal I strain in Saimiri has great potential.     

The proteolytic digestion of ox neurofilaments with trypsin and alpha-chymotrypsin.

Brief digestion of ox neurofilaments with trypsin liberates fragments that are soluble and have molecular weights ranging from 164 000 to 97 000. Peptide fingerprinting indicates that these regions, termed the tryptic head-regions, arise from the 205 000- and 158 000-mol.wt. components of the triplet. The remains of the parent polypeptides sediment with normal filaments and have been termed tail-regions. Digestion of neurofilaments with chymotrypsin also liberates soluble fragments (chymotryptic head-regions) but these have mol.wts. 171 000 and 119 000, though they too originate from the higher-molecular-weight triplet polypeptides. Tryptic and chymotryptic head-regions have extensive homology, and a low (less than or equal to 20%) helix content. Electron microscopy shows that chymotryptic digestion rapidly reduces the length of filaments, probably because this enzyme preferentially attacks the 72 000-mol.wt. polypeptide. In contrast, brief digestion with trypsin does not reduce filament length even though more than 90% of the two higher-molecular-weight components have been cleaved. These results indicate that the backbone of native filaments is formed from the 72 000-mol.wt. polypeptide together with the tail-regions from the 205 000- and 158 000-mol.wt. polypeptides. The corresponding head-regions of these components, which can represent nearly 75% of each molecule, are not necessary for preserving the backbone of native neurofilaments and are therefore good candidates for being the side arms that connect these filaments in nerve cells.     

The efficacy of biobehavioral and compliance interventions in the adjunctive treatment of mild pregnancy-induced hypertension

This investigation assessed the efficacy of a biobehavioral intervention in the adjunctive treatment of mild pregnancy-induced hypertension (PIH), a potentially serious complication of pregnancy in which normotensive women develop hypertension, proteinuria, and edema of unknown etiology late in gestation. Forty-five women with symptoms of PIH were randomly assigned to one of three treatment conditions: bed rest alone (the most common obstetrical treatment), bed rest with individualized compliance enhancement training, or a four-session biobehavioral treatment consisting of bed rest, compliance enhancement training, and individualized thermal biofeedback-assisted relaxation training. Results indicated that while blood pressure for the bed rest and compliance enhancement groups continued to rise and pose an increasing health risk to maternal and fetal well-being, subjects in the biobehavioral group maintained their blood pressure at a significantly lower, and presumably safer, level. The biobehavioral treatment is hypothesized to affect blood pressure levels in subjects with mild PIH through the mediation of the sympathetic nervous system, decreasing peripheral vascular resistance and cardiac output. The results of this investigation suggest that the biobehavioral intervention may be an effective adjunct to bed rest in the treatment of mild PIH remote from term.     

Breathing during sleep with mild hypoxia

To investigate ventilatory response to mild hypoxia during non-rapid-eye-movement sleep, we administered approximately 16% O2 (which corresponds to concentrations found in commercial high altitude air craft) to 12 normal subjects by using a Venturi mask, which did not alter the breathing pattern during this study. Under mild hypoxia, inspiratory minute ventilation during sleep showed an initial rapid increase (P less than 0.001) but then declined significantly (P less than 0.001) and stabilized. Stable levels differed among individuals and, compared with those measured before hypoxia, were significantly lower in some subjects, higher in one, and essentially unchanged in the others. The initial rapid increase in minute ventilation after mild hypoxia during sleep correlated with the respective values of hypoxic ventilatory response during the awake state (P less than 0.01), but the final lowered levels did not. We conclude that the ventilatory response after mild hypoxia during sleep is biphasic and hypoxic depression exerts considerable influence on ventilation under mild hypoxia during sleep. So we should take hypoxic depression into consideration to evaluate the response to hypoxia during sleep.     

Tissue-specific regulation of rat estrogen receptor mRNAs

The estrogen receptor (ER) is present in a wide variety of mammalian tissues and is required for physiological estrogen responses, including estrogen-induced tissue-specific changes in gene expression. We studied the estrogen regulation of the mRNAs encoding the ER in rat uterus, liver, and pituitary. Ovariectomized (21-28 day post surgery) female CD-1 rats were injected daily with 17 beta-estradiol (E2, 10 micrograms/100 g BW) for 0, 1, or 4 h, 1, 3, or 7 days and compared with intact controls. Steady-state levels of ER mRNA were quantified using a human ER cDNA probe. Only one hybridizing species of approximately 6.2 kilobase (kb) was detected in uterine and liver RNA, similar to that observed in MCF7 human breast cancer cells. However, the ER mRNA regulation by E2 differed in direction depending on the tissue examined. In uterus, ER mRNA increased 3- to 6-fold after ovariectomy, and returned to intact levels within 24 h of E2 replacement. In contrast, liver ER mRNA declined 1.5- to 3-fold after ovariectomy and returned to intact levels after 1-3 days of E2. In pituitary tissue two hybridizing forms of ER mRNA were observed, with one species migrating at 6.2 kb, equivalent to the form in other tissues, and a second smaller species at approximately 5.5 kb. The lower molecular weight species varied somewhat in abundance from animal to animal, averaging about 20% of the intensity of the 6.2 kb band. The ER mRNA forms were regulated positively with E2.(ABSTRACT TRUNCATED AT 250 WORDS)     

新疆温泉煤田早、中侏罗世孢粉组合及其地层意义*

新疆温泉煤田艾肯拜尔段和柯克它乌组的孢粉化石,计有42属59种.根据孢粉类型和含量变化等特征,建立2个孢粉组合(自下而上):1. Dictyophyllidites-Chordasporites-Jugasporites 组合;2. Cyathidites-Neoraistrickia-Pseudopicea 组合.第一组合产于艾肯拜尔段,时代可能为早侏罗世,第二组合产于柯克它乌组,时代暂定为早、中侏罗世.根据孢粉组合反映的植物群面貌是:裸子植物非常茂盛,其中以松柏纲为主,蕨类植物较少(包括真蕨纲植物);反映的古气候属于温暖湿润的亚热带型.     

Biological activity and metabolic clearance of recombinant human follicle stimulating hormone produced in Sp2/0 myeloma cells

Human follicle stimulating hormone is a pituitary glycoprotein that is essential for the maintenance of ovarian follicle development and testicular spermatogenesis. Like other members of the glycoprotein hormone family, it contains a common a subunit and a hormone specific subunit. Each subunit contains two glycosylation sites. The specific structures of the oligosaccharides of human follicle stimulating hormone have been shown to influence both thein vitro andin vivo bioactivity. Since the carbohydrate structure of a protein reflects the glycosylation apparatus of the host cells in which the protein is expressed, we examined the isoform profiles,in vitro bioactivity and metabolic clearance of a preparation of purified recombinant human follicle stimulating hormone derived from a stable, transfected Sp2/0 myeloma cell line, and pituitary human follicle stimulating hormone. Isoelectric focussing and chromatofocussing studies of human follicle stimulating hormone preparations both showed a more basic isoform profile for the recombinant human follicle stimulating hormone compared to that of pituitary human follicle stimulating hormone. The recombinant human follicle stimulating hormone had a significantly higher radioreceptor activity compared to that of pituitary human follicle stimulating hormone, consistent with a greaterin vitro potency. Pharmacokinetic studies in rats indicated a similar terminal half life (124 min) to that of the pituitary human follicle stimulating hormone (119 min). Preliminary carbohydrate analysis showed recombinant human follicle stimulating hormone to contain high mannose and/or hybrid type, in addition to complex type carbohydrate chains, terminating with both2,3 and2,6 linked sialic acids. These results demonstrate that recombinant human follicle stimulating hormone made in the Sp2/0 myeloma cells is sialylated, has a more basic isoform profile, and has a greaterin vitro biological potency compared to those of the pituitary human follicle stimulating hormone.     

Branch-point attack in group II introns is a highly reversible transesterification, providing a potential proofreading mechanism for 5'-splice site selection.

By examining the first step of group II intron splicing in the absence of the second step, we have found that there is an interplay of three distinct reactions at the 5'-splice site: branching, reverse branching, and hydrolytic cleavage. This approach has yielded the first kinetic parameters describing eukaryotic branching and establishes that group II intron catalysis can proceed on a rapid timescale. The efficient reversibility of the first step is due to increased conformational organization in the branched intermediate and it has several important mechanistic implications. Reversibility in the first step requires that the second step of splicing serve as a kinetic trap, thus driving splicing to completion and coordinating the first and second step of splicing. Facile reverse branching also provides the intron with a proofreading mechanism to control the fidelity of 5'-splice site selection and it provides a kinetic basis for the apparent mobility of group II introns.