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PubMed2006

A stochastic population dynamics model for Aedes aegypti: formulation and application to a city with temperate climate.

Aedes aegypti is the main vector for dengue and urban yellow fever. It is extended around the world not only in the tropical regions but also beyond them, reaching temperate climates. Because of its importance as a vector of deadly diseases, the significance of its distribution in urban areas and the possibility of breeding in laboratory facilities, Aedes aegypti is one of the best-known mosquitoes. In this work the biology of Aedes aegypti is incorporated into the framework of a stochastic population dynamics model able to handle seasonal and total extinction as well as endemic situations. The model incorporates explicitly the dependence with temperature. The ecological parameters of the model are tuned to the present populations of Aedes aegypti in Buenos Aires city, which is at the border of the present day geographical distribution in South America. Temperature thresholds for the mosquito survival are computed as a function of average yearly temperature and seasonal variation as well as breeding site availability. The stochastic analysis suggests that the southern limit of Aedes aegypti distribution in South America is close to the 15 degrees C average yearly isotherm, which accounts for the historical and current distribution better than the traditional criterion of the winter (July) 10 degrees C isotherm.

Aedes↗
PubMed1997

Novel oxylipins from the temperate red alga Polyneura latissima: evidence for an arachidonate 9(S)-lipoxygenase.

The oxylipin chemistry of the temperate red alga Polyneura latissima has been investigated. The structures of three novel oxylipins, 8-[1'(Z),3'(Z),6'(Z)-dodecatriene-1'-oxy]- 5(Z),7(E)-octadienoic acid, 7(S*)-hydroxy-8(S*),9(S*)-epoxy-5(Z),11(Z),14(Z)-eicosatrienoic acid, 7(R*)-hydroxy-8(S*),9(S*)-epoxy-5(Z),11(Z),14(Z)-eicosatrienoic acid, together with two known eicosanoids, 9(S)-hydroxy-5(Z),7(E),11(Z),14(Z)-eicosatetraenoic acid, and 9,15-dihydroxy-5(Z),7(E),11(Z),13(E)-eicosatetraenoic acid, were elucidated by spectroscopic methods and chemical degradation. The oxygenation pattern of these oxylipins suggests that P. latissima metabolizes polyunsaturated fatty acids via a 9(S)-lipoxygenase.

Arachidonate Lipoxygenases↗
PubMed1999

Influences of subzero thermal acclimation on mitochondrial membrane composition of temperate zone marine bivalve mollusks.

The phospholipid and phospholipid fatty acid composition of gill mitochondrial membranes from two temperate zone marine bivalve mollusks, the quahog, Mercenaria mercenaria, and the American oyster, Crassostrea virginica, were examined after acclimation to 12 and -1 degree C. Cardiolipin (CL) was the only phospholipid with proportions altered upon acclimation to -1 degree C, increasing 188% in the mitochondrial membranes of M. mercenaria. Although the ratio of bilayer stabilizing to destabilizing lipids is frequently associated with cold acclimation in ectothermic species, no change was found in this ratio in either of the species. Polyunsaturated fatty acids (PUFA) were found only to increase in C. virginica with cold acclimation, with total n-3 PUFA increasing in the phospholipid phosphatidylethanolamine, total n-6 PUFA increasing in CL, and total PUFA increasing in phosphatidylinositol. Monounsaturated fatty acids, not PUFA, were found to have increased in M. mercenaria, with 18:1 n-9 increasing by 150% in CL, and 20:1 increasing in both CL and phosphatidylcholine, by 146 and 192%, respectively. These manipulations of membrane phospholipid and fatty acid composition may represent an attempt by these species to help maintain membrane function at low temperatures.

Adaptation, Physiological↗
PubMed1981

Pyomyositis: tropical disease in a temperate climate.

Two cases of pyomyositis or bacterial abscess of striated muscle in adults are presented. One patient was initially diagnosed as having acute thrombophlebitis of the lower extremity. Computerized tomography was helpful in establishing the correct diagnosis. The other patient presented with a closed compartment syndrome following blunt trauma. Both patients responded to open drainage and antibiotic therapy, although the diagnosis was delayed for over three weeks in one patient. Although common in the tropics, pyomyositis is unusual in the temperate zone. Unfamiliarity with this entity remains the major obstacle to appropriate management.

Abscess↗
PubMed1975

Ion exchange tempering of glass ophthalmic lenses.

We performed low velocity drop-ball tests using 5/8-, 7/8-, and 1-inch diameter steel balls on ophthalmic crown glass lenses chemically tempered by the ion exchange process. Four representative dioptric strengths (+ 2.50 spherical, - 2.50 spherical, -2.50 cylindrical, and plano) were studied with the isolated lenses mounted, convex side up, on the American National Standards Institute Z80 test block. New ion exchange lenses exhibited a 100 to 350% greater capacity for attenuation of energy from low velocity, large size missiles than matched lenses of similar strength prepared by the conventional heat-treating and air-quenching process.

Eye Injuries↗
PubMed1985

Hybrid between temperate phage P22 and virulent phage MB78.

Bacteriophage MB78, a virulent phage of Salmonella typhimurium can not grow in rifampicin resistant mutant of the host. However, the temperate phage P22 which grows normally in this host helps MB78 to grow in its non-permissive host. P22 can not itself multiply under the condition of mixed infection and the burst size of MB78 is very much reduced. The burst sizes of both are reduced even when the permissive host LT2 is mixedly infected with P22 and MB78. When rifampicin resistant mutants are mixedly infected, only P22-specific mRNAs are produced in the early stage. This is followed by transcriptions from both P22 and MB78 genomes. Subsequently, only MB78-specific messengers are detected in the infected host. Hybrids between the two phages have been isolated from the mixedly infected cells. These hybrids which contain only 15-20% of P22 genome can grow in the rifampicin resistant mutants of the host. The analysis of hetero-duplex between MB78 and hybrid phages revealed the presence of at least three mismatch regions. Experiments are in progress to identify the parts of P22 genome present in the hybrid phage.

Crosses, Genetic↗
PubMed1992

Effect of the beta-adrenoceptor antagonist, propranolol, on feeding induced by noradrenaline and muscimol in rats kept at high and temperate-ambient temperatures.

Both the gamma-aminobutyric acid (GABA) receptor agonist, muscimol, and noradrenaline stimulated the feeding behavior of rats in the two environments. When noradrenaline or muscimol was administered, however, the food intake at 26 degrees C was greater than that at 33 degrees C. In addition, the stimulatory effect of noradrenaline on food intake was significantly depressed by propranolol pretreatment at both temperatures. The stimulatory effect of muscimol on food intake was significantly depressed by the propranolol pretreatment at 33 degrees C but not at 26 degrees C. Some eating-stimulatory subsystems associated with feeding behavior induced by noradrenaline or muscimol might have been depressed in the hot environment, thus the food intake increased by these drugs in rats acclimated to the hot environment was less than that in rats acclimated to the temperate environment.

Animals↗
PubMed1983

Immunocytochemical identification of the mesotocin- and vasotocin-producing systems in the brain of temperate and desert lizard species and their modifications by cold exposure.

Using immunofluorescent techniques, mesotocin (MT) and vasotocin (VT) neurosecretory systems were identified in the brain of different lizards: one temperate species living in southern France and three desert species coming from southern Algeria. In the four species, MT and VT were shown to be synthesized in specific neurons located in the anterior preoptic area (POA), the supraoptic (SON), paraventricular (PVN), and ventromedial (VMN) nuclei. The neurosecretory axons of the POA neurons terminated in the vicinity of the lamina terminalis; in the three desert species, several additional VT fibers extended more rostrally, going into the olfactory bulb. The axons originating in SON, PVN, and VMN ended either in the external zone of the rostral median eminence (ME) near the adenohypophyseal portal vessels, or in the neural lobe of the hypophysis. A short exposure to cold (4 degrees) in some specimens of Lacerta muralis induced a differential response in the dorsal and ventral parts of the PVN. Whereas the dorsal part remained unchanged, the ventral part instead appeared to be essentially composed of small neurons void of secretory granules. Cold exposure also led to a marked accumulation of both MT and VT in the internal zone of the ME, but of only VT in the external ME zone. On the other hand, a conspicuous amount of MT appeared in adenohypophyseal cells.

Animals↗
PubMed1990

Control of gene expression in the temperate coliphage 186. VIII. Control of lysis and lysogeny by a transcriptional switch involving face-to-face promoters.

The lysogenic and early lytic operons of the temperate coliphage 186 are transcribed divergently. Primer extension mapping of the 5' ends of these in vivo transcripts showed that the rightward lytic promoter, pR, and the leftward lysogenic promoter, pL, are arranged face-to-face, with their transcripts overlapping by 60 bases. We examined the control of transcription from pR and pL using galK as a reporter gene. The product of the lysogenic cI gene strongly repressed pR transcription while allowing pL transcription. The product of the lytic apl gene (formerly CP75) strongly repressed pL transcription while allowing pR transcription. Thus, the cI-pR-pL-apl region functioned as a transcriptional switch, determining whether transcription was lytic or lysogenic. Also, the cI gene product was able to stimulate pL, possibly by alleviating an inhibition of pL transcription caused by convergent transcription from pR. Other consequences of the face-to-face promoter arrangement are discussed.

Base Sequence↗
PubMed1985

Post-infective malabsorption in the temperate zone.

A series of 37 adults normally resident in Britain have been investigated for persistent bowel symptoms following acute enteritis. 26 had intestinal malabsorption, of whom 12 had been travelling in the Mediterranean area, whereas 10 developed their illness at home. Mild jejunal mucosal abnormalities were found in cases with and without malabsorption, and the intraepithelial lymphocyte count correlated more closely with the degree of malabsorption than did the histological grading. Over 80% of severe cases were folate deficient. Enterobacteria were cultured from the jejunal fluid in 30% of cases. Our observations confirm that post-infective malabsorption occurs sporadically in adults in the temperate zone and is occasionally severe. The condition involves small bowel contamination with enterobacteria, and it differs from acute tropical sprue only in its greater tendency to spontaneous recovery.

Adolescent↗
PubMed1987

The attachment sites of T5-host range temperate coliphages.

The attachment sites of 13 temperate coliphages were determined. Specialized transduction of proAB mutants was shown by eight isolates and of a his mutant by another two. Two isolates were concluded to integrate at atthtt and the integration site of one isolate remained undetermined.

Base Sequence↗
PubMed1991

House dust mite sensitization in children and residential characteristics in a temperate region.

House dust mite (Hdm) infestation used to be rare in Stockholm, but Hdm-sensitized children are now frequently observed, which probably indicates an increased infestation rate. This study was performed to elucidate determinants of Hdm sensitization in children living in the area. In a case-control study, 53 Hdm-sensitized children (cases), a group of non-Hdm-sensitized atopic children (N = 54), and a group of nonallergic neighborhood children (N = 53) were included. Mattress dust was analyzed with ELISA for content of Hdm allergens. Indoor humidity and temperature were measured, and questionnaire data were collected. Asthma was significantly more common in the Hdm-sensitized group than in the atopic control group. Hdm allergens were found in 40%, 19%, and 23% of the dust samples of the case group, atopic group, and neighborhood control groups, respectively. Only 15% of the dust samples of the Hdm-sensitized children contained Hdm allergens above the recommended threshold levels of sensitization of 2000 ng/gm of dust. Inadequate ventilation, which partly appeared to be a consequence of energy saving, appeared to be a risk factor for Hdm sensitization. This result may apply also to other temperate regions and suggests that the problem is preventable.

Adolescent↗
PubMed1985

Effects of high ambient temperature on respiration rate, rectal temperature, fetal development and thyrold gland activity in tropical and temperate breeds of sheep.

The effects of high ambient temperatures on rectal temperature (RT), respiration rate (RR), fetal development and serum thyroxine (T(4)) concentrations were stuaied in two experiments involving 35 ewes and 26 lambs from the following ewe groups: 1) Barbados Blackbelly (B), a tropical breed; 2) Dorset (D), a temperate breed; and 3) Blackbelly x Dorset crosses (BxD). Data were obtained on four B, five D and five BxD ewes exhibiting estrus during the summer (Exp. 1). In Exp. 2, eight B, seven D and six BxD ewes were maintained in two environmental chambers (cool, 22.2C; hot, 33.8C) from day 125 of gestation to seven days before the expected lambing date for each breed group (D and BxD, 140+/-1; B, 144+/-1 day of gestation). The B and BxD ewes were more heat-tolerant than D ewes as measured by significantly lower RT and RR in each experiment. Mean lamb birth weight, crown-rump length, number of functional uterine caruncles and caruncle weight and size did not vary significantly among breed groups or temperature chamber (Exp. 2), and there was no indication that the high temperature imposed caused fetal dwarfing in lambs removed from the uterus at a standard age of seven days before expected parturition. Serum T(4) varied markedly among breed groups (P<0.05) in each experiment with B ewes having the lowest and BxD ewes the highest concentration. In Exp. 1, follicular stage T(4) concentrations in B and BxD ewes were lower (P<0.02) than those during the luteal stage of the estrous cycle. The decrease in D ewes was not significant. High ambient temperature (Exp. 2) depressed T(4) levels in D ewes (P<0.05) and also depressed the pituitary-thyroid response to thyrotropin releasing hormone in D lambs. Such was not the case in B and BxD ewes and their lambs.

Journal Article↗
PubMed1989

Interrelationships between water, food and digestible energy intake in desert and temperate goats.

Intra- and interspecific relationships between energy intake and digestible energy intake (DEI) and water turnover (WTO) in Black Bedouin and temperate (Swiss Saanen) goats were analyzed. Available data from other species of mammals were also evaluated. A highly significant linear relationship between WTO and DEI holds within breeds of goats under different levels of DEI and between breeds which vary considerably in their body weight and metabolic expenditure (WTO ml/kg per day = -5.4 + 0.911 DEI kcal/kg per day, n = 34, r2 = 0.99, Sb = 0.057). In lactating goats the relation between WTO rate (minus water secreted in milk) and DEI is the same as that measured in non-lactating ones. Mammals with quite a different body weight have the same WTO per unit of metabolism--about 1 mol of water per 5 mol of oxygen--although their absolute turnover is very different. Furthermore, the above relationship is similar to the relationship between WTO:DEI found in goats here. (WTO ml/kg per day = 5.8 + 0.849 x kcal/kg per day, n = 8, r2 = 0.99, Sb = 0.030, where x is the caloric equivalent of oxygen consumption.

Animals↗
PubMed1996

Tropical pyomyositis in a temperate climate: a case report.

Pyomyositis is an abscess-forming infection of large skeletal muscles, usually with Staphylococcus aureus. Although it is common in the tropics and relatively rare in temperate climates, imported cases due to growing global mobility may be expected to increase its incidence outside tropical regions. Early diagnosis and correct management are imperative in this potentially fatal disorder, and require a high degree of clinical suspicion. A case report is presented demonstrating typical aspects of diagnosis and treatment.

Abscess↗
PubMed1988

Lactate dehydrogenases in Antarctic and temperate fish species.

1. The kinetics of lactate dehydrogenase (both forward and back reaction) in cardiac and skeletal muscle of an Antarctic teleost have been compared with a temperate teleost of comparable morphology and ecology. 2. In both species the forward reaction (pyruvate to lactate) is maximally activated at 2.5-4 mM pyruvate and inhibited above this level. 3. The Michaelis constant (Km) for pyruvate is not significantly different between muscle types or between species when measured at their normal environmental temperature. 4. Km for pyruvate varies with temperature in a positive direction. 5. The back reaction (lactate to pyruvate) is maximally activated by 12-16 mM lactate but only in skeletal muscle of the antarctic species is there inhibition above this level. 6. The Km for lactate is significantly (P less than 0.05) lower in the Antarctic fish cardiac muscle. 7. While the two species are morphologically and ecologically similar, differences at the biochemical level are discussed with respect to environmental temperature range and conservation of enzymic characteristics.

Animals↗
PubMed1992

Insertion into the Mycobacterium smegmatis genome of the aph gene through lysogenization with the temperate mycobacteriophage Ms6.

A derivative of the temperate mycobacteriophage Ms6 containing the aph gene from transposon Tn5 was constructed. In the transductants the aph gene was integrated in the bacterial genome. The aph gene is stably maintained in the absence of positive selection after more than 150 generations. The results presented in this report show that Ms6 can be used as a vehicle for the integration of foreign DNA into the Mycobacterium smegmatis genome.

Cloning, Molecular↗
PubMed1980

A physical map of the genome of the Bacillus subtilis temperate phage rho 11.

A cleavage map of Bacillus subtilis temperate phage rho 11 was constructed with restriction endonucleases SalI, BamHI and BglII, which cut the genome into 6, 7 and 21 fragments, respectively. The molecular weight of the rho 11 genome was calculated to be 78 x 10(6). Among other endonucleases tested, PvuII, EcoRI and XbaI cleaved the genome into more than 25 fragments, while HaeIII, StuI, BalI and BamNx did not cut the genome at all. The rho 11-coded thymidylate synthetase gene, thyP11, was found to be located in the SalI-D fragment, which was in the central region of the genome.

Bacillus subtilis↗