WHO at country level--a little impact,no strategy.

The acid test of WHO''s effect on the world''s health is its impact at country level. Unless it has an impact there, all of its declarations, its debates at the World Health Assembly, its conferences, its pamphlets, its political manouvering in Geneva and the regions, all of these come to nothing. Working as it does through national governments, WHO insists that it has no role in directly managing or delivering health care. Judging WHO''s impact in individual countries is therefore difficult--its approaches are largely indirect, and initiatives may take years to bear fruit. But from the meagre resources that WHO makes available at country level it is clear why its country operations are criticised as the weakest link in an already weak chain of influence from its headquarters in Geneva to the people in its member states. Poorly funded, undertrained, and with no clear strategy to follow, its staff at country level stand little chance of making an impact.     

High-frequency P element loss in Drosophila is homolog dependent

P transposable elements in Drosophila melanogaster can undergo precise loss at a rate exceeding 13% per generation. The process is similar to gene conversion in its requirement for a homolog that is wild type at the insertion site and in its reduced frequency when pairing between the homologs is inhibited. However, it differs from classical gene conversion by its high frequency, its requirement for P transposase, its unidirectionality, and its occurrence in somatic and premeiotic cells. Our results suggest a model of P element transposition in which jumps occur by a "cut-and-paste" mechanism but are followed by double-strand gap repair to restore the P element at the donor site. The results also suggest a technique for site-directed mutagenesis in Drosophila.     

The inhibitory effects of pyrocarbonic acid diethyl ester on lactobacillus casei and its phage Jl – A novel strategy for phage control in technical fermentation processes

The effects of pyrccarbonic acid diethyl ester (PADE) on Lactobacillus casei Sl and its phage Jl was investigated in relation to the control of phages in the dairy industry and other technica fermentation processes. PADE exhibited a bacteriostatic effect at 0.5 to 8 mM and a bactericidal effect at 10 mM or higher. It inhibited the growth of the phage at its bacteriostatic and bactericidal concentrations. The growth inhibition of the phage was reversible at the bacteriostatic concentrations but complete and irreversible at the bactericidal concentrations. PADE inactivated the free phage within several minutes; 10 and 30 mM of PADE inactivated 90 and 100%, respectively, of the phage. It completely decomposed into ineffective components in several minutes. The bacteria grew almost normally when they were inoculated after the complete decomposition of PADE. These four characteristics of PADE – its bactericidal effect, its inhibitory effect on phage growth, its phage-inactivating effect and its decomposition – suggest a novel strategy for phage control in technical fermentation processes, including the dairy industry.     

稻-麦轮作系统土壤水解酶及氧化还原酶活性对开放式空气CO2浓度增高的响应

研究了FACE条件下(CO2浓度增加200μmol·mol^-1)水稻、小麦不同生育期0～10cm土层土壤脲酶、磷酸酶、芳基硫酸酯酶、脱氢酶活性的变化．结果表明,FACE条件下,土壤脲酶活性在冬小麦生育前期低于对照,在孕穗期高于对照;在水稻生育前期高于对照,在成熟期低于对照．磷酸单酯酶活性在冬小麦生育期高于对照;在水稻分蘖期高于对照,在生育后期(拔节期、抽穗期和成熟期)低于对照．芳基硫酸酯酶活性在小麦越冬期和孕穗期低于对照,在分蘖期和成熟期高于对照;在水稻生育期间均高于对照．脱氢酶活性在小麦和水稻的生育前期低于对照,在后期高于对照．     

Anaerobic treatment of poultry mortality in a temperature-phased leachbed-UASB system

Anaerobic digestion has been proposed as an alternative to the conventional disposal methods of burial, incineration, rendering and aerobic composting. A temperature-phased system consisting of one UASB (at 55 degrees C) and three leach-bed reactors (at ambient temperatures) was tested for its efficiencies in treating poultry mortality. The thermophilic UASB was difficult to start-up. It also showed signs of inhibited methanogenesis. Chemical parameters such as long chain fatty acids, volatile fatty acids and ammonia concentrations were all very high for the thermophilic UASB. Lowering its temperature to 35 degrees C enhanced its stability and improved its performances. Lowering the pH of the 55 degrees C UASB also improved its chemical oxygen demand (COD) reduction efficiency as well as its methane production rate. The results were compared to that of another similar system where the UASB reactor was maintained at 35 degrees C instead of at 55 degrees C.     

Investigation of the open ring form of nicotinamide adenine dinucleotide.

In strong alkali, nicotinamide adenine dinucleotide (NAD+) undergoes a ring opening of the nicotinamide ring. The open form of NAD+, ONAD, has two pKa values at--1.9 and 11.2 and absorbs maximally at 350 nm in its acidic form, at 372 nm in its neutral form, and at 340 nm in its aniomic form. ONAD has the chemical properties expected for a Schiff base of 2-carboxamideglutacondialdehyde (CGDA) and adenosine diphosphate ribosylamine. The decomposition of ONAD has been studied over a wide range of pH. A final product of ONAD hydrolysis is the base fluorescent compound 2-hydroxynicotinaldehyde. In the pH range 10--13, CGDA can be trapped as an intermediate, which absorbs maximally at 345 nm in its anionic form and at 320 nm in its neutral form, pKa = 2.9. The yield of 2-hydroxynicotinaldehyde from ONAD has been estimated as 95% at NaOH concentrations of 5 N and above, and is postulated to result from ring closure of CGDA. The pseudobase hydroxide ring addition adduct of NAD+, psiNAD-OH, is reversibly formed from NAD+ and is the 370-nm precursor of ONAD.     

Determinants in microbial colonization of the murine gastrointestinal tract: pH, temperature, and energy-yielding metabolism of Torulopsis pintolopesii.

Torulopsis pintolopesii is an indigenous yeast that colonizes the secreting epithelia in the stomachs of mice and rats. A wild-type strain of this microbe was isolated and identified. To attempt to learn characteristics of the yeast that are advantageous to it in colonizing its natural habitat in vivo, we examined some aspects of its nutrition and energy-yielding metabolism and some environmental conditions that influence its growth in vitro. The yeast appeared to be limited in the compounds it can utilize as carbon and nitrogen sources. It grew best at 37 degrees C and did not grow at 23 or 43 degrees C. It grew optimally at neutral pH but could grow aerobically at pH values as low as 2.0 and anaerobically at pH values as low as 3.4. As assessed by measurements of growth rates and yield coefficients, it grew better aerobically than anaerobically. When grown aerobically, it had a cyanide-sensitive system for taking up O(2) and tested positively for cytochrome c oxidase activity. A petite mutant strain isolated from the wild-type strain had a growth rate and yield coefficient when incubated aerobically that were essentially the same as those of the wild-type parent grown anaerobically. Likewise similar to the wild-type parent grown anaerobically, the petite strain, though incubated aerobically, did not take up O(2). Yeast-free mice associated with either the wild-type or the petite mutant strain were colonized at essentially the same rates and to similar final population levels by both strains. The yeast's capacity to respire may be of little advantage to it in its natural environment. By contrast, its abilities to grow best at 37 degrees C and to grow at low pH values are undoubtedly advantageous characteristics in this respect. The limitations in its carbon and nitrogen nutrition are difficult to evaluate as ecological factors in its colonization of the natural habitat.     

The function of hemocyanin in respiration of the blue crab Callinectes sapidus.

Blood PO2 in the blue crab Callinectes sapidus, a very active species of tropical origin, is lower at 22 degrees C than that of larger crabs in colder waters. These low oxygen levels permit its hemocyanin to be highly oxygenated at the gill, and to deliver almost half of its oxygen to the tissues in resting animals. Sustained muscular activity results in conspicuous decreases in blood PO2, pH and hemocyanin oxygenation. Although the venous reserve is fully utilized, hemocyanin oxygenation at the gill decreases so much that there is no change in its total quantitative function. The large Bohr shift becomes functional during activity, but its quantitative importance is not clear.     

Synthesis and in vitro/in vivo evaluation of novel oral N-alkyl- and N,N-dialkyl-carbamate esters of entacapone

Entacapone has a relatively low oral bioavailability which may, in part, be due to its low aqueous solubility at low pH and/or its hydrophilic character at neutral pH. Various novel N-alkyl and N,N-dialkyl carbamate esters of entacapone were synthesized as possible prodrugs of entacapone in order to increase its aqueous solubility at an acidic pH and to increase its lipophilicity at neutral pH. Oral bioavailability of entacapone and selected carbamate esters were investigated in rats. Both N-alkyl and N,N-dialkyl carbamate esters were relatively stable against chemical hydrolysis at pH 7.4 (t1/2 = 14.9-20.7 h), but hydrolyzed rapidly (t1/2 = 0.8-2.7 h) in human serum. However, in contrast to N-alkyl carbamates, N,N-dialkyl carbamates did not release entacapone in in vitro enzymatic hydrolysis (human serum) studies. N-Alkyl carbamates, 2a-c, showed increased aqueous solubility at pH 7.4, of which 2a and 2c also show increased aqueous solubility at pH 5.0, compared to entacapone. In addition to increased aqueous solubility, 2c showed increased lipophilicity at pH 7.4. However, two N-alkyl carbamates of entacapone did not increase the oral bioavailability of the parent drug in rats. Thus, it can be concluded that the relatively low lipophilicity of entacapone is not the cause of its low bioavailability.     

Acetylcholinesterase: how is structure related to function?

In accordance with its biological role, termination of neurotransmission at cholinergic synapses by rapid hydrolysis of the neurotransmitter, acetylcholine, acetylcholinesterase is one of nature's most efficient enzymes. Solution of its three-dimensional structure revealed that its active site is located at the bottom of a deep and narrow gorge. Such an architecture was unanticipated in view of its high turnover number. The present review examines how the highly specialized structure of acetylcholinesterase, with its sequestered active site, contributes to its catalytic efficacy, and discusses how the traffic of substrate and products to and from the active site is controlled.     

达氏鳇不同发育期胚胎对低温的耐受研究

研究了达氏鳇12个发育期胚胎经过不同低温（2 ℃、3 ℃、5 ℃、7 ℃和8 ℃）处理12 h、24 h、2 d、3 d、6 d、10 d、15 d、20 d和30 d后的孵化率和仔鱼成活率.结果表明,卵黄栓期、隙状胚孔期、神经管闭合期胚胎在2～8 ℃水温下,处理24 h后孵化率为0;卵裂期、囊胚早期、原肠中期胚胎在2～8 ℃水温下,处理3 d后孵化率低于30%;囊胚晚期、原肠早期、眼基期、尾芽期、心跳期和尾达头部期胚胎在5～8 ℃水温下,处理3 d后孵化率、仔鱼成活率超过70%;随低温处理时间延长,胚胎和仔鱼的死亡率增加,处理时间与孵化率、仔鱼成活率呈负相关;囊胚晚期、原肠早期、眼基期胚胎在5 ℃水温下耐受力较强,处理10 d后孵化率、仔鱼成活率超过70%.本研究表明,达氏鳇胚胎发育过程中囊胚晚期、原肠早期和眼基期胚胎可以在某一低温下进行短期保存,其孵化率、仔鱼成活率与常温（16～17 ℃）下没有显著差异.这对于达氏鳇胚胎（受精卵）的长途运输有重要意义.     

Promoter-independent cold-shock induction of cspA and its derepression at 37°C by mRNA stabilization

The gene for CspA, the major cold-shock protein of Escherichia coli is known to be dramatically induced upon temperature downshift. Here, we report that three-base substitutions around the Shine–Dalgarno sequence in the 159-base 5'-untranslated region of the cspA mRNA stabilizes the mRNA 150-fold, resulting in constitutive expression of cspA at 37°C. This stabilization was found to be at least partially due to resistance against RNase E degradation. The cold-shock induction of cspA was also achieved by exchanging its promoter with the non-cold-shock lpp promoter. The results presented indicate that the cspA gene is efficiently transcribed even at 37°C. However, the translation of the cspA mRNA is blocked because of its extreme instability at 37°C. The presented results also demonstrate that the cspA gene is constitutively transcribed at all temperatures; however, its expression at 37°C is prevented by destabilizing its mRNA.     

Developing axons continue to grow at their tip after synapsing with their appropriate target

The contacts a growing neuron's axon makes with its synaptic targets are believed to inhibit further growth at the axon tip. Inhibition of axon growth has been difficult to examine in vivo, where studies have focused on populations of neurons with multiple targets, making the influence of a single target difficult to determine. Results of a direct test of the influence of synapse formation on axon growth are presented for the axon of the S interneuron in the leech, which has a single synaptic target that can decidedly inhibit growth at the axon's tip during regeneration in adults. Surprisingly, in embryos, after synapsing with its target, each S cell axon grew for several days, including growth at its tip, nearly doubling its length. Therefore, synaptic contact with the target does not stop further growth at the axon's tip.     

Selection of a cold-adapted bacterium for bioremediation of wastewater at low temperatures

Amongst more than 1000 isolates collected in various cold environments, the strain Arthrobacter psychrolactophilus Sp 31.3 has been selected for its ability to grow and to produce exoenzymes at low temperatures, its inability to grow at 37°C, its non-halophilic character and its growth versatility on various media. This non-pathogenic strain displays a strong resistance to desiccation and storage at room temperature and is suitable for the production of freeze-dried bacterial starters. When grown in a synthetic wastewater at 10°C, the strain induces a complete clarification of the turbid medium and efficiently hydrolyses proteins, starch and lipids in the broth. Furthermore, this strain has a remarkable capacity to improve the biodegradability of organic compounds in wastewater as indicated by a BOD₅/COD ratio of 0.7.     

Preface

Summary— Diffusion theory played a major role in the development of biology as an exact science. The question is raised, however, as to its relevance and applicability in the molecular interactions which occur in metabolism in the living cell. This review looks at diffusion theory from its inception and subsequent introduction into biology, its shortcomings with regard not only to whole-body physiology, but more pertinently at the intracellular level, with its failure to offer a rational basis for metabolic regulation in the internum of the cell. The conclusion is reached that although diffusion inevitably occurs within cells, its role is of little importance with regard to most metabolic activity. In comparison, perfusion of the internal surfaces of the cell by streaming of the fluid compartment of the cytoplasm seems to be the modus operandi which allows molecular interactions to occur at rates far beyond those that diffusion would permit, and at the same time offers a mechanism which permits sensitive control of metabolic activity.     

Surgical anatomy of the anterior abdominal wall in normal viscera, dolichoviscerosis and visceroptosis

There are three types in position of the abdominal internal organs: visceronorm, dolichoviscerosis and visceroptosis. The anterior abdominal wall also has its own anatomical peculiarities at every type of the internal organs position. Anatomical differences of its structure at visceronorm and dolichoviscerosis in comparison with visceroptosis are characterized as following: the area of aponeurotic formations of the anterior abdominal wall at dolichoviscerosis and visceroptosis increases and that of the muscular-decreases. Umbilical and inguinal rings are essentially dilated in comparison with those at visceronorm. It means that at dolichoviscerosis and visceroptosis there are anatomical prerequisites for development of external hernias in the anterior abdominal wall. A considerable mobility of the intestinal tract loops at dolichoviscerosis and visceroptosis results in certain disturbances of its function and their outlet into hernial sacs.     

Chromosomal aberrations induced by maleic hydrazide and related compounds in Chinese hamster cells in vitro.

The cytotoxic effects and chromosomal abnormalities induced by maleic hydrazide (MH) and its salts were investigated in cultured V79 cells. MH, and its potassium (K-MH) and diethanolamine (DEA-MH) salts were tested. MH was 5--14 times more cytotoxic than its salts and almost 4.5 times less toxic than the related compound, hydrazine dihydrochloride (HDC). MH salts had very weak cytotoxicity; the LD50 values on V79 cells on exposure for 3 h in vitro were (in microgram/ml) 1100 (MH), 12 000 (DEA-MH), 20 000 (K-MH), 230 (HDC) and 10 000 (NaCl). Both MH and its salts--but neither HDC nor NaCl--caused chromosomal aberrations in cultured V79 cells. The maximal frequencies of aberrant cells in cultures exposed to the compounds for 3 h in vitro were 18% (mh at 100 microgram/ml), 18% (K-MH at 20 000 microgram/ml) and 13% (DEA-MH at 20 000 microgram/ml). Maximal frequencies observed in cultures treated with HDC or NaCl were 10% (HDC at 400 microgram/ml) and 5% NaCl at 10 000 microgram/ml). Those of positive groups were 97% (N-methyl-N'-nitro-N-nitrosoguanidine, MNNG, at 5 microgram/ml) and 16% (ethyl methanesulfonate, EMS, at 400 microgram/ml). These frequencies of MH and its salts were 3.25--4.5 times those in untreated control cells. These results suggested that MH and its salts had weak inducibili     

Determinants in Microbial Colonization of the Murine Gastrointestinal Tract: pH, Temperature, and Energy-Yielding Metabolism of Torulopsis pintolopesii

Torulopsis pintolopesii is an indigenous yeast that colonizes the secreting epithelia in the stomachs of mice and rats. A wild-type strain of this microbe was isolated and identified. To attempt to learn characteristics of the yeast that are advantageous to it in colonizing its natural habitat in vivo, we examined some aspects of its nutrition and energy-yielding metabolism and some environmental conditions that influence its growth in vitro. The yeast appeared to be limited in the compounds it can utilize as carbon and nitrogen sources. It grew best at 37°C and did not grow at 23 or 43°C. It grew optimally at neutral pH but could grow aerobically at pH values as low as 2.0 and anaerobically at pH values as low as 3.4. As assessed by measurements of growth rates and yield coefficients, it grew better aerobically than anaerobically. When grown aerobically, it had a cyanide-sensitive system for taking up O₂ and tested positively for cytochrome c oxidase activity. A petite mutant strain isolated from the wild-type strain had a growth rate and yield coefficient when incubated aerobically that were essentially the same as those of the wild-type parent grown anaerobically. Likewise similar to the wild-type parent grown anaerobically, the petite strain, though incubated aerobically, did not take up O₂. Yeast-free mice associated with either the wild-type or the petite mutant strain were colonized at essentially the same rates and to similar final population levels by both strains. The yeast's capacity to respire may be of little advantage to it in its natural environment. By contrast, its abilities to grow best at 37°C and to grow at low pH values are undoubtedly advantageous characteristics in this respect. The limitations in its carbon and nitrogen nutrition are difficult to evaluate as ecological factors in its colonization of the natural habitat.