ABSTRACT
Zika virus (ZIKV) is an emerging mosquito-borne flavivirus transmitted mainly by Aedes species of mosquitos. Although the infection is usually mild and self-limiting, it is emerging as a public health challenge in tropical and subtropical countries owing to its unprecedented pathogenicity and increased risk for fetal malformations and neurological symptoms. Cutaneous manifestations as for other mosquito-borne viruses remain a hallmark of the disease. This article provides a detailed overview on ZIKV infection, including its varied cutaneous clinical manifestations and diagnostic aspects, and also provides detailed insights into its pathogenesis in human skin.
Subject(s)
Exanthema/etiology , Skin Diseases/virology , Skin/pathology , Zika Virus Infection/complications , Zika Virus , Diagnosis, Differential , Fever/etiology , Humans , Zika Virus Infection/pathologyABSTRACT
This study longitudinally examined age-related changes in the match-running performance of retained and released elite youth soccer players aged 8-18 years. The effect of playing position on age-related changes was also considered. Across three seasons, 263 elite youth soccer players were assessed in 1-29 competitive matches (988 player-matches). For each player-match, total distance and distances covered at age group-specific speed zones (low-speed, high-speed, sprinting) were calculated using 1 Hz or 5 Hz GPS. Mixed modeling predicted that match-running performance developed nonlinearly, with age-related changes best described with quadratic age terms. Modeling predicted that playing position significantly modified age-related changes (P < 0.05) and retained players covered significantly more low-speed distance compared with released players (P < 0.05), by 75 ± 71 m/h (mean ± 95% CI; effect size ± 95% CI: 0.35 ± 0.34). Model intercepts randomly varied, indicating differences between players in match-running performance unexplained by age, playing position or status. These findings may assist experts in developing training programs specific to the match play demands of players of different ages and playing positions. Although retained players covered more low-speed distance than released players, further study of the actions comprising low-speed distance during match play is warranted to better understand factors differentiating retained and released players.
Subject(s)
Athletic Performance/physiology , Running/physiology , Soccer/physiology , Adolescent , Age Factors , Child , Humans , Longitudinal Studies , Male , Models, Theoretical , Soccer/classificationABSTRACT
The purpose of this study was to investigate the effect of accumulating 60 min of exercise on endothelial function and triacylglycerol concentrations following the ingestion of a high-fat breakfast and lunch in 14 adolescent boys (aged 12 to 14 years). Two, 2-day main trials (control and exercise) were completed in a counter-balanced, cross-over design. Participants were inactive on day 1 of the control trial but on day 1 of the exercise trial completed 6 × 10 min runs at 70% of peak oxygen uptake, spread over the day. On day 2, triacylglycerol concentrations and flow-mediated dilation (FMD) were measured prior to, and following, ingestion of the high-fat meals. In the control trial, FMD was reduced by 30% and 33% (P < 0.001) following the high-fat breakfast and lunch; following exercise these reductions were negated (main effect trial, P = 0.002, interaction effect trial × time, P < 0.001). The total and incremental areas under the triacylglycerol concentration vs time curve were reduced by 11% and 16% in the exercise trial; however, these differences were not significant (P > 0.05). These results support the concept of accumulating physical activity for health in adolescents as the accumulated exercise attenuated the decline in FMD seen following the consumption of high-fat meals.
Subject(s)
Brachial Artery/physiology , Diet, High-Fat , Endothelium, Vascular/physiology , Exercise/physiology , Postprandial Period/physiology , Triglycerides/blood , Vasodilation/physiology , Accelerometry , Adolescent , Area Under Curve , Brachial Artery/diagnostic imaging , Child , Cross-Over Studies , Dietary Fats/metabolism , Humans , Linear Models , Male , UltrasonographyABSTRACT
This study investigated if the quantity of high-speed running (movements >15 km.h(-1) completed in the first 15 min of competitive football matches differed from that completed in the corresponding 15 min of the second half. 20 semi-professional soccer players (age 21.2±3.6 years, body mass 76.4±3.8 kg, height 1.89±0.05 m) participated in the study. 50 competitive soccer matches and 192 data files were analysed (4±2 files per match) using Global Positioning Satellite technology. Data were analysed using 2-way repeated measures ANOVA and Pearson correlations. No differences were found between the first 15 min of each half for the distance completed at high-speed (>15 km.h(-1) or sprinting (>21 km.h(-1), or in the number of sprints undertaken (p>0.05). However, total distance covered was shorter (1st half vs. 2nd half: 1746±220 vs. 1644±224 m; p<0.001) and mean speed lower (1st half vs. 2nd half: 7.0±0.9 vs. 6.6±0.9 km.h(-1); p<0.001) in the first 15 min of the second half compared to the first. The correlations between the duration of the half-time interval and the difference in the high-speed running or sprinting between first and second halves (0-15 min) were very small (r=0.08 [p=0.25] and r=0.04 [p=0.61] respectively). Therefore, this study did not find any difference between the amount of high-speed running and sprinting completed by semi-professional soccer players when the first 15 min of the first and second half of competitive matches were compared The maintenance of high-speed running and sprinting, as total distance and mean speed declined, may be a function of the pacing strategies adopted by players in competitive matches.
Subject(s)
Athletic Performance/physiology , Running/physiology , Soccer/physiology , Adolescent , Analysis of Variance , Athletes , Geographic Information Systems , Humans , Time Factors , Young AdultABSTRACT
The validity and reliability of a battery of field-based performance tests was examined. The opinions of coaches, fitness professionals and players (n=170, 172 and 101 respectively) on the importance of performance testing were established using a questionnaire. On 2 occasions, separated by 7 days, 80 elite, young soccer players (mean±SD [and range]: age 13.2±2.6 [8.9-19.1] years; stature 1.59±0.18 m [1.32-1.91]; body mass 50.6±17.1 [26.5-88.7] kg) completed a battery of field-based tests comprised of heart rate response to a submaximal Multi-stage fitness test, 3 types of vertical jump, sprints over 10 and 20 m, and an agility test. Physical performance testing was considered important by coaches (97%), fitness professionals (94%) and players (83%). The systematic bias ratio and the random error components of the 95% ratio limits of agreement for the first and second tests, for the U9-U11 vs. U12-U14 vs. U15-U18 age groups, were [Systematic bias (*/÷ ratio limits)]: Heart rate (Level 5): 0.983 (*/÷ 1.044) vs. 0.969 (*/÷ 1.056) vs. 0.983 (*/÷ 1.055); Rocket jump: 0998 (*/÷ 1.112) vs. 0.999 (*/÷ 1.106) vs. 0.996 (*/÷ 1.093); 10 m sprint: 0.997 (*/÷ 1.038) vs. 0.994 (*/÷ 1.033) vs. 0.994 (*/÷ 1.038); Agility test: 1.010 (*/÷1.050) vs. 1.014 (*/÷1.050) vs. 1.002 (*/÷1.053). All tests, except heart rate recovery from the Multi-stage fitness test, were able to distinguish between different ability and age groups of players (p<0.05). Thus, the field-test battery demonstrated logical and construct validity, and was shown to be a reliable and objective tool for assessing elite, young soccer players.
Subject(s)
Athletic Performance/physiology , Exercise Test , Soccer/physiology , Adolescent , Age Factors , Analysis of Variance , Focus Groups , Heart Rate/physiology , Humans , Physical Fitness/physiology , Reproducibility of Results , Surveys and QuestionnairesABSTRACT
OBJECTIVE: To determine whether neuropsychological measures differ between patients with idiopathic Parkinson's disease (PD) who acquire dementia within 10 years of disease onset versus those who acquire dementia later in the disease course, using data from the longitudinal Sydney Multicentre Study of PD. METHODS: The Sydney Multicentre Study of PD is a cohort of 149 community-living de novo patients with idiopathic PD studied over a 20-year period. Detailed clinical and neuropsychological tests were administered at baseline and at 3, 5, 10, 15 and 20 years, and the dementia status was assessed at each time point. For the present study, the pattern of longitudinal neuropsychological measures was compared between PD patients with the onset of dementia in the middle (5-10 years, mid-stage PD dementia, N = 20) or late (>10 years, late-stage PD dementia, N = 10) disease stages using analysis of variance and multiple linear regression modelling, and the relationship between age and dementia onset assessed using survival statistics. RESULTS: Mid-stage PD dementia patients were differentiated from late-stage PD dementia patients by having greater deficits in vocabulary skills prior to and at dementia onset. The pattern of cognitive deficits following dementia onset are similar, and there is no difference in the age of dementia onset between the different PD groups. CONCLUSIONS: These data suggest that the evolution of dementia within PD occurs at around 70 years of age, regardless of the time of PD onset, and affects cognitive domains in a similar way, although patients with earlier-onset PD have a preserved linguistic ability prior to dementia onset.
Subject(s)
Dementia/etiology , Dementia/psychology , Neuropsychological Tests , Parkinson Disease/complications , Parkinson Disease/psychology , Age Factors , Age of Onset , Aged , Antiparkinson Agents/therapeutic use , Bromocriptine/therapeutic use , Cognition/physiology , Cohort Studies , Disease Progression , Female , Humans , Levodopa/therapeutic use , Longitudinal Studies , Male , Memory/physiology , Middle Aged , Neurologic Examination , New South Wales , Survival AnalysisABSTRACT
Near-adult cats, fasted overnight, and given a single meal of a complete amino acid diet without arginine, developed hyperammonemia and showed clinical symptoms of ammonia toxicity within 2 hours. One cat (2.7 kilograms) died 4.5 hours after ingesting only 8 grams of the diet. Since ornithine also prevented hyperammonemia, it appears that the domestic cat cannot synthesize ornithine.
Subject(s)
Ammonia/blood , Animal Nutritional Physiological Phenomena , Arginine/deficiency , Cats/metabolism , Amino Acids/metabolism , Ammonia/toxicity , Animals , Arginine/metabolism , Female , Male , Ornithine/metabolism , Time FactorsABSTRACT
Thousands of pet cats die each year with dilated cardiomyopathy, the cause of which is unknown. Although taurine is present in millimolar concentrations in the myocardium of all mammals, taurine depletion has not previously been associated with a decrease in myocardial function in any species. In this study, low plasma taurine concentrations associated with echocardiographic evidence of myocardial failure were observed in 21 cats fed commercial cat foods and in 2 of 11 cats fed a purified diet containing marginally low concentrations of taurine for 4 years. Oral supplementation of taurine resulted in increased plasma taurine concentrations and was associated with normalization of left ventricular function in both groups of cats. Since myocardial concentrations of taurine are directly related to plasma concentrations and low plasma concentrations were found to be associated with myocardial failure in cats, a direct link between decreased taurine concentration in the myocardium and decreased myocardial mechanical function is proposed.
Subject(s)
Cardiomyopathy, Dilated/veterinary , Cat Diseases , Taurine/deficiency , Animals , Cardiomyopathy, Dilated/diagnosis , Cardiomyopathy, Dilated/etiology , Cats , Dogs , Echocardiography , Humans , Myocardium/metabolism , Retinal Degeneration/etiology , Retinal Degeneration/veterinary , Taurine/blood , Taurine/metabolismABSTRACT
Cattle grazing St. Augustine grass growing on peaty muck soils in the Florida Everglades developed anemia associated with the presence of Heinz bodies and suboptimal concentrations of selenium in blood. Selenium supplementation corrected the anemia, prevented Heinz body formation, increased the body weight of cows and calves, and elevated blood selenium. This may be the first recorded example of widespread anemia in a population due to selenium deficiency.
Subject(s)
Anemia, Hemolytic/veterinary , Cattle Diseases/etiology , Heinz Bodies/ultrastructure , Selenium/deficiency , Anemia, Hemolytic/drug therapy , Anemia, Hemolytic/etiology , Animal Feed , Animals , Body Weight , Cattle , Cattle Diseases/drug therapy , Hematocrit , Hemoglobins/analysis , Selenium/administration & dosage , Selenium/bloodABSTRACT
This study examined the effect of ingesting a high or low glycemic index (GI) meal during a short-term recovery period on endurance running capacity. On two occasions, seven men (age 30.0+/-2.6 yr, body mass 60.7+/-1.4 kg, VO (2max) 62.1+/-2.2 ml.kg (-1).min (-1)) ran at 70% VO (2max) on a level treadmill for 90 min (R1), followed by a 4 h recovery (REC) and a further exhaustive run at the same speed (R2). Twenty minutes after R1, each subject consumed an isoenergetic meal containing either high GI (HGI, GI=77) or low GI (LGI, GI=37) carbohydrate providing 1.5 g CHO.kg (-1) BM. During REC, subjects also ingested a prescribed volume of water equal to 150% of their BM loss during R1. The duration of R2 in the HGI trial was 15% longer than in the LGI trial (HGI: 86.6+/-10.7 min vs. LGI: 75.2+/-8.1 min, p<0.05). The subjects also achieved complete rehydration after REC on both occasions. In conclusion, the consumption of a HGI meal during a 4 h recovery improved endurance capacity in a subsequent run; however, the precise mechanism(s) by which this takes place is yet to be clarified.
Subject(s)
Dietary Carbohydrates/administration & dosage , Glycemic Index , Physical Endurance/physiology , Running/physiology , Adult , Athletes , Drinking , Exercise Test , Fluid Therapy/methods , Humans , Male , Oxygen Consumption , Postprandial Period , Single-Blind Method , Time FactorsABSTRACT
Forty Yersinia pestis isolates from endemic foci of plague in the Republic of Georgia, and six Y. pestis isolates from neighbouring former Soviet Union countries, were analysed for their biochemical and phenotypic properties, and their genetic relatedness was compared with Y. pestis strains KIM and CO92 by pulsed-field gel electrophoresis (PFGE). In addition, 11 Y. pestis isolates from the USA, together with published nucleotide sequences from Y. pestis strains KIM, CO92 and 91001, were compared with the 46 isolates in the present collection using multilocus sequence typing (MLST), based on sequence data for the 16S rRNA, hsp60, glnA, gyrB, recA, manB, thrA and tmk loci. Four virulence gene loci (caf1, lcrV, psaA and pla) were also sequenced and analysed. Two sequence types (ST1 and ST2), which differed by a single nucleotide, were identified by MLST. With the exception of a single isolate (771G), all of the Georgian Y. pestis isolates belonged to ST2. PFGE also grouped the Georgian Y. pestis isolates separately from the non-Georgian isolates. Overall, PFGE discriminated the Y. pestis isolates more effectively than MLST. The sequences of three of the four virulence genes (lcrV, psaA and pla) were identical in all Georgian and non-Georgian isolates, but the caf1 locus was represented by two allele types, with caf1 NT1 being associated with the non-Georgian isolates and caf1 NT2 being associated with the Georgian isolates. These results suggest that Georgian Y. pestis isolates are of clonal origin.
Subject(s)
Plague/epidemiology , Virulence Factors/genetics , Yersinia pestis/classification , Bacterial Typing Techniques , Electrophoresis, Gel, Pulsed-Field , Genes, Bacterial , Georgia (Republic)/epidemiology , Molecular Sequence Data , Sequence Analysis, DNA , Virulence , Yersinia pestis/genetics , Yersinia pestis/pathogenicityABSTRACT
BACKGROUND: It is well documented that heat acclimation of six or more sessions of at least 60 min duration prolongs the time to exhaustion during endurance walking, cycling and running in the heat. However, this type of acclimation is not specific to team sport activity and the effect of acclimation on prolonged high-intensity intermittent running has not yet been investigated. OBJECTIVE: To assess the impact of an intermittent acclimation protocol on distance run during team sport activity. METHODS: The impact of four short heat acclimation sessions (30-45 min of the Loughborough Intermittent Shuttle Test; LIST) on high-intensity intermittent running capacity (LIST) in the heat (30 degrees C, 27% relative humidity (RH)), was examined. Seventeen female well-trained games players were split into three groups: an acclimation group (30 degrees C, 24% RH), a moderate training group (18 degrees C, 41% RH) and a control group who did not complete any training between the main trials (pre-acclimation and post-acclimation). The pre-acclimation (A) and post-acclimation (B) trials were separated by 28 days to control for menstrual phase and verified using hormonal analysis. The four acclimation or moderate training sessions utilising the LIST were completed with one or two rest days interspersed between each session in a 10-day period prior to the post-acclimation trial (B). RESULTS: In the post-acclimation trial distance run was increased by 33% in the acclimation group (A: 7703 (SEM 1401) m vs B: 10215 (SEM 1746) m; interaction group x trial p<0.05), but was unchanged in the moderate and control groups. The acclimation group had a lower rectal temperature (interaction group x trial x time p<0.01) due to a lower rate of rise, and an increase in thermal comfort1 after acclimation (End A: 7 (SEM 2) vs 6 (SEM 2); interaction group x trial p<0.01). There was no difference in serum progesterone, aldosterone or cortisol concentrations following acclimation or between groups. CONCLUSION: Four 30-45 min sessions of intermittent exercise induced acclimation, and resulted in an improvement in intermittent running exercise capacity in female games players. A lower rectal temperature and a concomitant rise in thermal comfort may be partly responsible for the improvement in exercise capacity.
Subject(s)
Acclimatization/physiology , Hot Temperature , Physical Endurance/physiology , Running/physiology , Body Temperature/physiology , Case-Control Studies , Drinking/physiology , Female , Heart Rate/physiology , Humans , Sweating/physiology , Temperature , Time FactorsABSTRACT
Previous experiments have shown that increasing the dietary crude protein (CP) of cats does not increase urea cycle enzymes or alanine amino transferase as occurs in rats. Also when an essential amino acid (EAA) is limiting in a diet for growing kittens, the kittens do not exhibit an amino acid imbalance when other EAAs are added to the diet. To study the metabolic basis for these observations which are different from that found in omnivores and herbivores, the hypothesis that increased dietary CP decreases methionine catabolism, so more is spared for growth, was tested. Fifteen male kittens were randomly assigned to one of three dietary treatments. Each diet contained 2.5 g l-methionine/kg diet and 200, 300 or 500 g CP/kg diet. The livers and kidneys were removed and assayed for methionine transaminase (MTA), cystathionase (CASE) and cystathionine synthase (CS). Free amino acid concentrations were determined in liver, kidney and plasma. The 300 and 500 g CP/kg groups had significantly greater kidney weights and body weight gains than the 200 g CP/kg group. Hepatic MTA activity was lower in the 300 than the 200 or 500 g CP/kg groups (p < 0.05). Renal MTA and CASE activities were 35% and 50% greater, respectively, for the 500 g CP/kg group than for the 200 g CP/kg diet group (p < 0.05). Renal CS activities for the 300 and 500 g CP/kg groups were 29% (p > 0.05) and 38% (p < 0.05) greater, respectively, than the 200 g CP/kg group. Cyst(e)ine concentrations were lower in the livers of the 500 g CP/kg group than the 200 g CP/kg group (p < 0.05). Cystathionine was lower in plasma and kidney from the 500 g CP/kg diet group than from the 200 g CP/kg diet group (p < 0.05). It was concluded that the metabolic basis for the increased growth of kittens fed diets marginally limiting in methionine, with increasing concentrations of dietary CP, was not mediated through decreased enzyme activity associated with the catabolism of methionine, but was the result of an increase in food (methionine) intake.
Subject(s)
Cats/growth & development , Dietary Proteins/pharmacology , Methionine/administration & dosage , Methionine/metabolism , Weight Gain , Amino Acids, Essential/administration & dosage , Amino Acids, Essential/metabolism , Aminoacyltransferases/metabolism , Animal Feed , Animal Nutritional Physiological Phenomena , Animals , Animals, Newborn , Cats/metabolism , Cystathionine beta-Synthase/metabolism , Cystathionine gamma-Lyase/metabolism , Diet/veterinary , Dose-Response Relationship, Drug , Kidney/enzymology , Liver/enzymology , Male , Nutritional Requirements , Organ Size , Random Allocation , Specific Pathogen-Free OrganismsABSTRACT
The herbicide glyphosate, N-(phosphonomethyl) glycine, has been used extensively in the past 40years, under the assumption that side effects were minimal. However, in recent years, concerns have increased worldwide about the potential wide ranging direct and indirect health effects of the large scale use of glyphosate. In 2015, the World Health Organization reclassified glyphosate as probably carcinogenic to humans. A detailed overview is given of the scientific literature on the movement and residues of glyphosate and its breakdown product aminomethyl phosphonic acid (AMPA) in soil and water, their toxicity to macro- and microorganisms, their effects on microbial compositions and potential indirect effects on plant, animal and human health. Although the acute toxic effects of glyphosate and AMPA on mammals are low, there are animal data raising the possibility of health effects associated with chronic, ultra-low doses related to accumulation of these compounds in the environment. Intensive glyphosate use has led to the selection of glyphosate-resistant weeds and microorganisms. Shifts in microbial compositions due to selective pressure by glyphosate may have contributed to the proliferation of plant and animal pathogens. Research on a link between glyphosate and antibiotic resistance is still scarce but we hypothesize that the selection pressure for glyphosate-resistance in bacteria could lead to shifts in microbiome composition and increases in antibiotic resistance to clinically important antimicrobial agents. We recommend interdisciplinary research on the associations between low level chronic glyphosate exposure, distortions in microbial communities, expansion of antibiotic resistance and the emergence of animal, human and plant diseases. Independent research is needed to revisit the tolerance thresholds for glyphosate residues in water, food and animal feed taking all possible health risks into account.
Subject(s)
Glycine/analogs & derivatives , Herbicides/adverse effects , Animals , Carcinogens , Ecotoxicology , Environmental Monitoring , Glycine/adverse effects , Humans , Plants , Soil Microbiology , Soil Pollutants/adverse effects , Water Pollutants, Chemical/adverse effects , GlyphosateABSTRACT
Domoic Acid (DA) is a marine-based neurotoxin. Dietary exposure to high levels of DA via shellfish consumption has been associated with Amnesic Shellfish Poisoning, with milder memory decrements found in Native Americans (NAs) with repetitive, lower level exposures. Despite its importance for protective action, the clinical relevance of these milder memory problems remains unknown. The purpose of this study was to determine whether repeated, lower-level exposures to DA impact everyday memory (EM), i.e., the frequency of memory failures in everyday life. A cross-sectional sample of 60 NA men and women from the Pacific NW was studied with measures of dietary exposure to DA via razor clam (RC) consumption and EM. Findings indicated an association between problems with EM and elevated consumption of RCs with low levels of DA throughout the previous week and past year after controlling for age, sex, and education. NAs who eat a lot of RCs with presumably safe levels of DA are at risk for clinically significant memory problems. Public health outreach to minimize repetitive exposures are now in place and were facilitated by the use of community-based participatory research methods, with active involvement of state regulatory agencies, tribe leaders, and local physicians.
Subject(s)
Bivalvia , Dietary Exposure/adverse effects , Kainic Acid/analogs & derivatives , Marine Toxins/toxicity , Memory/drug effects , Neurotoxins/toxicity , Shellfish Poisoning/epidemiology , Adolescent , Adult , Aged , Animals , Dietary Exposure/prevention & control , Female , Food Contamination , Humans , Kainic Acid/toxicity , Male , Middle Aged , Public Health , Research , Shellfish Poisoning/etiology , Young AdultABSTRACT
We performed a prospective cohort study to quantify the number of cases of patient-to-patient transmission of extended-spectrum beta-lactamase-producing Klebsiella species on perianal surveillance culture. Among 27 patients who acquired Klebsiella pneumoniae infection, 14 had infections (52%) that were due to patient-to-patient transmission, and 6 (22%) had a subsequent positive extended-spectrum beta-lactamase clinical culture results.
Subject(s)
Klebsiella Infections/microbiology , Klebsiella Infections/transmission , Klebsiella pneumoniae/enzymology , beta-Lactamases/biosynthesis , Anal Canal/microbiology , Female , Humans , Klebsiella Infections/epidemiology , Male , Maryland/epidemiology , Middle Aged , Prospective StudiesABSTRACT
In this study, 27 volunteers received one of three non-O group 1 Vibrio cholerae strains in doses as high as 10(9) CFU. Only one strain (strain C) caused diarrhea: this strain was able to colonize the gastrointestinal tract, and produced a heat-stable enterotoxin (NAG-ST). Diarrhea was not seen with a strain (strain A) that colonized the intestine but did not produce NAG-ST, nor with a strain (strain B) that produced NAG-ST but did not colonize. Persons receiving strain C had diarrhea and abdominal cramps. Diarrheal stool volumes ranged from 154 to 5,397 ml; stool samples from the patient having 5,397 ml of diarrhea were tested and found to contain NAG-ST. The median incubation period for illness was 10 h. There was a suggestion that occurrence of diarrhea was dependent on inoculum size. Immune responses to homologous outer membrane proteins, lipopolysaccharide, and whole-cell lysates were demonstrable with all three strains. Our data demonstrate that V. cholerae of O groups other than 1 are able to cause severe diarrheal disease. However, not all strains are pathogenic for humans: virulence of strain C may be dependent on its ability both to colonize the intestine and to produce a toxin such as NAG-ST.
Subject(s)
Gastroenteritis/etiology , Vibrio cholerae/pathogenicity , Adolescent , Adult , Amino Acid Sequence , Animals , Antibodies, Bacterial/analysis , Cholera Toxin/biosynthesis , Enterotoxins/analysis , Enterotoxins/toxicity , Female , Humans , Male , Molecular Sequence Data , Rabbits , Vibrio cholerae/immunology , VirulenceABSTRACT
Two Salmonella typhi mutants, 541Ty (Vi+) and 543Ty (Vi-), auxotrophic for p-aminobenzoate and adenine, were evaluated as live oral vaccines. 33 volunteers ingested single doses of 10(8), 10(9), or 10(10) vaccine organisms, while four others received two 2 X 10(9) organism doses 4 d apart. No adverse reactions were observed. Vaccine was recovered from coprocultures of 29 of 37 vaccinees (78%) and from duodenal string cultures of two; repeated blood cultures were negative. The humoral antibody response to S. typhi O, H, Vi, and lysate antigens in serum and intestinal fluid was meager. In contrast, all vaccinees manifested cell-mediated immune responses. After vaccination, 69% of vaccinees overall and 89% of recipients of doses greater than or equal to 10(9) responded to S. typhi particulate or purified O polysaccharide antigens in lymphocyte replication studies but not to antigens of other Salmonella or Escherichia coli. All individuals, postvaccination, demonstrated a significant plasma-dependent mononuclear cell inhibition of wild S. typhi.