Mutational uncoupling of the transcriptional activation function of the TyrR protein of Escherichia coli K-12 from the repression function

The tyrosine repressor (TyrR) protein of Escherichia coli can function either as a transcriptional enhancer or as a repressor. The structural basis for these opposite effects was analyzed in specific tyrR deletion mutants constructed in vitro. The functional behavior of the mutant TyrR proteins was evaluated in vivo by using single-copy lacZ reporter systems based on the mtr promoter (10-fold activation by wild-type TyrR protein, mediated by phenylalanine or tyrosine) or the aroF promoter (over 20-fold repression by wild-type TyrR protein, mediated by tyrosine). A mutant TyrR protein lacking amino acids 2 to 9 was completely devoid of transcriptional activation function. Five additional mutant TyrR proteins lacking progressively greater numbers of N-terminal amino acids were likewise activation defective. The mutant TyrR proteins lacking amino acid residues 2 to 9 or 2 to 19 were essentially identical to the wild-type TyrR protein in their ability to repress the aroF promoter. Three other TyrR mutant proteins, lacking up to 143 amino acid residues from the N-terminal end of the protein, retained the ability to repress the aroF promoter, to different extents, in a tyrosine-dependent manner.

Expression and characterization of a canine hippocampal inwardly rectifying K+ current in Xenopus oocytes

1. An inwardly rectifying potassium current expressed in Xenopus laevis oocytes injected with canine hippocampal poly(A)+ RNA was investigated with the two-microelectrode voltage clamp technique. 2. Xenopus oocytes injected with canine hippocampal poly(A)+ RNA expressed a current activated by hyperpolarization. This current contained an instantaneous and a time-dependent component. Both components were inwardly rectifying and could be blocked by extracellular Cs+ or Ba2+. 3. The expressed current was carried mainly by K+. Its reversal potential measured in different [K+]os could be fitted by the Nernst equation with a slope of -50.7 per tenfold change in [K+]o. Extracellular Cl- and Na+ made minimal contributions to the current. 4. The activation of the expressed current depended on both voltage and [K+]o. Activation started near EK and the activation curve shifted along the voltage axis in parallel with EK when [K+]o was altered. 5. The activation time constants of the expressed current also depended on both voltage and [K+]o. The voltage dependence of the time constants was bell-shaped and the peak value was at a potential 30-50 mV more negative than EK. The voltage dependence of the time constants shifted along the voltage axis when EK was changed. 6. The poly(A)+ RNA extracted from canine hippocampus was fractionated in a 10-31% linear sucrose gradient. The size of the mRNA required to express the inwardly rectifying current was estimated to be around 4 kb. 7. In conclusion, the expressed current is an inwardly rectifying potassium current. The canine hippocampal mRNA should be an excellent source for expression-cloning of the inward rectifier channel.

Physical map location and transcriptional orientation of the tyrR gene of Escherichia coli K-12

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Rapid but transient atrophy of brown adipose tissue in capsaicin-desensitized rats

Our previous studies showed atrophy of brown adipose tissue (BAT) in capsaicin-desensitized rats during the period 11-28 days after injections [Cui et al., Am. J. Physiol. 259 (Regulatory Integrative Comp. Physiol. 28): R324-R332, 1990]. The objective of the present studies was to assess the rapidity with which the atrophy occurred and the extent to which recovery had occurred by 8 wk. Rats, either vehicle-injected controls or capsaicin injected, were studied 1, 3, 14, 28, and 52 days after the last injection. BAT was markedly atrophied at 1 day, having less total protein, fewer mitochondria (less total cytochrome oxidase and total uncoupling protein), and fewer cells (less DNA). Atrophy persisted for up to 14 days but had largely disappeared by 28-52 days. A transient reduction in body weight gain and white epididymal adipose tissue weight had also reversed by 28-52 days. We suggest that the rapid atrophy of BAT after capsaicin desensitization is secondary to the loss of sensory neuropeptides in its sensory nerves, neuropeptides that either exert a trophic effect on synthesis of mitochondria or an inhibitory influence on processes that promote degradation of mitochondria. The retardation of the normal age-associated increase in DNA content of BAT in the capsaicin-desensitized rat suggests that sensory neuropeptides might also modulate cell proliferation.

Long-term decrease in body fat and in brown adipose tissue in capsaicin-desensitized rats

Previous studies showed that atrophy of brown adipose tissue (BAT) of capsaicin-desensitized rats occurs rapidly and persists for up to 28 days. The rats do not, however, become any more obese than control rats, despite the frequent association of atrophied BAT with obesity. The objective of the present study was to assess longer-term effects of capsaicin desensitization on BAT and on energy balance. Rats were studied at 2.5, 3.5, and 8 mo after treatment. Major effects at 8 mo, mostly seen to a lesser extent at 3.5 mo but not at 2.5 mo, were a marked reduction in body weight that was largely attributable to a reduction in body fat but also to some stunting of growth and an atrophy or lack of growth of BAT (reduced weight and content of protein, DNA, cytochrome oxidase, and uncoupling protein). Resting metabolic rates and food intake at 8 mo were reduced in proportion to the smaller body size. We suggest that the lack of trophic influence of sensory neuropeptides on BAT proposed previously may extend to other organs, including white adipose tissue, and contribute to the reduced adiposity and the smaller body size of capsaicin-desensitized rats.

An improved europium release assay for complement-mediated cytolysis

An improved assay for complement-mediated cytolysis is described. The target cells are labeled with europium complexed to diethylenetriaminopentaacetate (Eu-DTPA). Cytolysis caused by antibody plus complement leads to the release of the Eu-DTPA complex which is then formed into a highly fluorescent chelate by the addition of 2-naphthoyltrifluoroacetone (2-NTA). The amount of europium chelate formed--a measurement of cell death--is then quantified with a time-resolved fluorometer. The results of the assay are reproducible. Complement-mediated cytolysis when measured by europium release was five times more sensitive than when measured by conventional 51Cr release and three times than when measured by trypan blue exclusion. Because europium does not decay, target cells can be labelled in batches and stored frozen until use, which speeds and simplifies the assay. Thus, europium release assay is a simple and quantitative method to measure complement-mediated cytolysis which is sensitive and more rapid than conventional assays.

Identification of Pigment Cell Antigens Defined by Vitiligo Antibodies

Patients with vitiligo have circulating antibodies to pigment cells. To characterize this response further and to identify the antigens defined by vitiligo antibodies, sera of 23 patients with vitiligo and 22 patients with unrelated conditions were analyzed by immunoprecipitation and SDS-PAGE analysis of 125I-labeled cell antigens on pigment and control cells. Antibodies to pigment cell antigens were present in 18 (78%) of the patients with vitiligo but in only three (14%) of the control patients (p less than 0.05). The antibodies were directed to one or more antigens with molecular weight (MW) in kilodaltons (kD) of approximately 35, 40-45, 75, 90, or 150. The responses were most commonly directed to the 40-45-kD, 75-kD, and 90-kD antigens. Antibodies to these antigens were present in 74%, 57%, and 35% of vitiligo patients versus in 14%, 9%, and 0% of control individuals. The 35-kD and 90-kD antigens were preferentially expressed on human pigment cells, whereas the 40-45-, 75-, and 150-kD antigens were expressed on both pigment and control cells. These antigens were labeled by the lactoperoxidase technique, suggesting that they are cell surface antigens. These results confirm that antibodies to pigment cells are associated with vitiligo. These antibodies are directed to several cell surface antigens, some of which are preferentially expressed on pigment cells.

Relation between the incidence and level of pigment cell antibodies and disease activity in vitiligo

Patients with vitiligo often have antibodies to pigment cells. To examine whether there is a relation between the presence of such antibodies and disease activity, sera of 24 patients with vitiligo (10 with active and 14 with inactive disease) and 19 normal individuals were tested for antibodies to pigment cell surface antigens using a live cell enzyme-linked immunoabsorbent assay. IgG pigment cell antibodies were present in 80% (eight of 10) of patients with active vitiligo but in none of those with inactive disease or in normal individuals. The antibody level of patients with active vitiligo (mean binding index [BI] 3.3 +/- 0.59) was significantly higher than in patients with inactive disease (BI 0.96 +/- 0.04) or normal individuals (BI 1.0 +/- 0.04, p less than 0.001). Antibodies present in eight patients with high titers of pigment cell antibodies reacted to three of four pigment cells but to only one of six unrelated cells. These findings indicate that a correlation exists between the incidence and level of pigment cell antibodies and the activity of vitiligo, and support the hypothesis that vitiligo is an autoimmune disease mediated by an immune reaction to pigment cells.

Role of hair follicles in the repigmentation of vitiligo

Vitiligo is a common pigment disease that is difficult to treat. The mechanism of repigmentation is not known. We combined Dopa-Toluidine Blue complex stain, hair follicle split-Dopa stain, and hair follicle split-scanning electron microscope (SEM) to observe the changes of melanocytes in 23 normal, 24 vitiliginous, and 36 repigmented skin specimens. We found that only active (Dopa-positive) melanocytes existed in the epidermis of normal skin. There were some inactive (Dopa-negative) melanocytes in the outer root sheaths of normal hair follicles, which form the melanocyte reservoir in human skin. In the patients with vitiligo the active melanocytes in the epidermis were totally missing, whereas the inactive melanocytes in the outer root sheaths of hair follicles were not affected. Treatment stimulated the inactive melanocytes in the middle and/or lower parts of the outer root sheaths of hair follicles to divide, proliferate, and migrate upward along the surface of the outer root sheath to the nearby epidermis, where the melanocytes continued to migrate radially to form the pigmented island visible clinically in repigmented vitiligo lesions. During the migration to the epidermis, the melanocytes matured gradually from an inactive phase to an active condition. In conclusion, the existence of these inactive melanocytes provided the melanocyte sources for repigmentation of vitiligo.

[American ginseng compound liquor on retarding-aging process]

71 cases with age over sixty were randomly divided into treated group and control group, and observed by single-blind method. 36 cases were administered with American ginseng compound liquor as a treated group, 35 cases were administered with American ginseng liquor only as a control group. The total effective rates of the treated group and the control group on symptoms associated with aging were 88.89% and 68.57% respectively (P less than 0.05). The effective rates of the treated group for Kidney-Yang, Kidney-Qi and Kidney-Yin deficiencies were 85.71%, 100% and 87.50% respectively. The effective rates of the control group were 81.82%, 100% and 61.53% respectively. The above results indicated that the symptoms of Kidney-Yang deficiency in the treated group were improved much better than those of the control group (P less than 0.05). Obviously, SOD activity of erythrocyte and SOD/LPO ratio increased remarkably and serum content of LPO decreased significantly in both groups (P less than 0.001). In the treated group, the functional months of age (physiological age) decreased from 751.77 +/- 5.215 to 743.53 +/- 5.144, the effective rate was 68.57%. It showed that these two recipes both had the efficiency on prolonging the functional age (P less than 0.05).

Capsaicin desensitization induces atrophy of brown adipose tissue in rats

Interscapular brown adipose tissue (BAT) of capsaicin-desensitized (Cap-Des) rats is atrophied, having a lower wet weight, a reduced total protein content, and as little as 10% of the normal content of uncoupling protein (UCP). Because the mitochondrial concentration of UCP, relative to other mitochondrial proteins, is not altered in Cap-Des rats, it is concluded that most of the mitochondria of BAT of Cap-Des rats have been lost. Consistent with this interpretation is a reduction of almost 40% of the overall thermogenic response to infused norepinephrine by anesthetized Cap-Des rats. Feeding a palatable diet had a delayed thermogenic effect and no trophic effect on BAT of Cap-Des rats. Food selection and intake were normal in Cap-Des rats, and diet-induced weight gain was the same as in control rats. Exposure of Cap-Des rats to cold for 1 or 7 days exerted a normal thermogenic effect on BAT but a delayed trophic effect. The cold-induced increase in thyroxine 5'-deiodinase in BAT occurred normally. Cap-Des rats were hypothermic at 1 day but normothermic by 7 days of cold exposure. The concentration of thyroid hormones in their blood was normal. It is suggested that the depletion of sensory neuropeptides in BAT presumed to be brought about by Cap-Des results either in loss of a trophic influence on mitochondriogenesis in BAT or in lack of an inhibitory influence on mitochondrial breakdown in BAT and leads to atrophy of BAT in rats living at 26 degrees C and an impaired response to stimulation by diet.(ABSTRACT TRUNCATED AT 250 WORDS)

[Analgesic and antipyretic effects of cyproheptadine]

Cyproheptadine-HCl raised the pain thresholds during hot plat test and writhing test in mice and tail flick test in rats, strengthened the hypnotic action by subthreshold dosage of sodium pentobarbital and chloral hydrate. The ED50 were 4.4 (3.2-5.7) and 12.4 (8.4-18.2) mg/kg 30 min after ip cyproheptadine in mice and rats, respectively. The ED50 was 0.14 (0.12-0.18) mg/kg 90 min after icv cyproheptadine in mice. Cyproheptadine po 20, 40 mg/kg and ip 10, 20 mg/kg showed significant antipyretic effects on yeast-induced pyrexia in rats.

[An autopsied case of a malignant lymphoma with a severe nephrotic syndrome overlapped by cirrhotic glomerulosclerosis]

A 52-year-old man, who had been diagnosed as having alcoholic liver cirrhosis, presented a chronic nephritic syndrome due to hepatic glomerulosclerosis. Ten months before death, massive proteinuria exceeding 40 g/day was noted. A renal biopsy revealed diffuse mesangial sclerosis, associated with an IgA deposition consistent with hepatic glomerulosclerosis. Although the nephrotic syndrome subsided with immunosuppressive therapy, he died of hepatic failure. Postmortem examinations disclosed a diffuse, medium-size B-cell lymphoma, involving the peritoneal and retroperitoneal organs and an IgA-positive plasmacytosis. His massive proteinuria seems to have been caused by the paraneoplastic syndrome of a malignant lymphoma.