Effect of high-fat diet on stress responsiveness in borderline hypertensive rats.

Stress in combination with genetic susceptibility is a factor in the development of hypertension. We used borderline hypertensive rats to investigate whether exposure to high-fat and/or junk-food diet at different stages of ontogeny has programing consequences on stress responses. Wistar dams were fed a high- or low-fat diet for 6 weeks prior to mating with spontaneously hypertensive males, and during gestation. At birth, litters were fostered either to a dam in the same or an alternative diet condition as during gestation. After weaning, male offspring were fed either a control-chow diet or an intermittent junk food fatty diet. Between postnatal days 57-61, half of the rats in each dietary group received daily social defeat sessions using a resident-intruder protocol, and the other half were unstressed controls. Blood pressure was measured indirectly both before and after each defeat session. On the final day, rats were killed for physiological measures. Socially defeated rats showed large increases in serum corticosterone concentration and adrenal hypertrophy, indicating the effectiveness of this non-adapting stressor. Serum corticosterone level was also higher in rats fed with the junk-food diet post-weaning compared with those fed with chow only, but there were no significant effects of gestational or lactational dietary history.

A microbiological study of Papillon-Lefévre syndrome in two patients.

AIM: To analyse the microflora of subgingival plaque from patients with Papillon-Lefévre syndrome (PLS), which is a very rare disease characterised by palmar-plantar hyperkeratosis with precocious periodontal destruction. METHODS: Bacterial isolates were identified using a combination of commercial identification kits, traditional laboratory tests, and gas liquid chromatography. Some isolates were also subjected to partial 16S rDNA sequencing. Plaque samples were also assayed for the presence of Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans in a quantitative enzyme linked immunosorbent assay (ELISA) using monoclonal antibodies. RESULTS: The culture results showed that most isolates were capnophilic and facultatively anaerobic species-mainly Capnocytophaga spp and Streptococcus spp. The latter included S. constellatus, S. oralis, and S. sanguis. Other facultative bacteria belonged to the genera gemella, kingella, leuconostoc, and stomatococcus. The aerobic bacteria isolated were species of neisseria and bacillus. Anaerobic species included Prevotella intermedia, P. melaninogenica, and P. nigrescens, as well as Peptostreptococcus spp. ELISA detected P gingivalis in one patient in all sites sampled, whereas A. actinomycetemcomitans was detected in only one site from the other patient. Prevotella intermedia was present in low numbers. CONCLUSIONS: Patients with PLS have a very complex subgingival flora including recognised periodontal pathogens. However, no particular periodontopathogen is invariably associated with PLS.

An examination of 'unidentified' Prevotella (formerly PINLO) using RAPD-PCR and partial 16S rRNA gene sequencing.

Prevotella intermedia- and Prevotella nigrescens-like organisms (PINLO) have been described as organisms which are phenotypically and biochemically similar to P. intermedia and P. nigrescens and the species P. pallens was created to include some of them. Other PINLO groups which do not fit the definition of P. pallens exist, and in this study these 'unidentified' Prevotella sp. were compared with P. corporis, P. intermedia, P. nigrescens and P. pallens using commercial identification kits, GLC, RAPD-PCR and partial 16S rRNA gene sequencing. The Rapid ID 32 A and the RapID ANA II system both identified all 'unidentified' Prevotella as P. intermedia. Similarly they gave this identification to all the species tested (with the exception of P. corporis using the RapID ANA II system) clearly demonstrating biochemical similarities. Gas liquid chromatography (GLC) analysis of the volatile end-products of fermentation could not distinguish between strains. RAPD-PCR using arbitrary primer L10 demonstrated intra-species homogeneity within PINLO strains with amplification profiles which differed from other Prevotella species tested. Cluster analysis of the amplification profiles confirmed species divisions and yielded a distinct 'unidentified' Prevotella cluster. Comparison of partial 16S rDNA sequences displayed 98% sequence similarity between the 'unidentified' Prevotella strains, although 2 strains, HST 1156 and HST 2160 displayed 100% identity. The highest similarity between groups was seen between 'unidentified' Prevotella strains and P. corporis (approximately 94% similarity). The DNA techniques used here confirm that 'unidentified' Prevotella strains are distinct from the other species of Prevotella tested, including P. pallens. Partial 16S rDNA sequence comparisons suggested a close relationship with P. corporis.

A cloud adult: the Staphylococcus aureus-virus interaction revisited.

BACKGROUND: Nasal carriage of Staphylococcus aureus is common among health care workers, but outbreaks caused by such carriers are relatively uncommon. We previously reported outbreaks of S. aureus skin infections that affected newborn infants and were attributed to an S. aureus nasal carrier who had had an associated upper respiratory tract infection (UR) during the outbreak period. OBJECTIVE: To investigate the contribution of a nasal methicillin-resistant S. aureus (MRSA) carrier (physician 4) who contracted a URI to an outbreak of MRSA infections that involved 8 of 43 patients in a surgical intensive care unit during a 3-week period. DESIGN: An epidemiologic study of an outbreak of MRSA infections and a quantitative investigation of airborne dispersal of S. aureus associated with an experimentally induced rhinoviral infection. SETTING: A university hospital. PARTICIPANTS: 43 patients in a surgical intensive care unit and 1 physician. MEASUREMENTS: Molecular typing was done, and risk factors for MRSA colonization were analyzed. Agar settle plates and volumeric air cultures were used to evaluate the airborne dispersal of S. aureus by physician 4 before and after a rhinoviral infection and with or without a surgical mask. RESULTS: A search for nasal carriers of MRSA identified a single physician (physician 4); molecular typing showed that the MRSA strain from physician 4 and those from the patients were identical. Multivariate logistic regression analysis identified exposure to physician 4 and duration of ventilation as independent risk factors for colonization with MRSA (P < or = 0.008). Air cultures showed that physician 4 dispersed little S. aureus in the absence of a URI. After experimental induction of a rhinovirus URI, physician 4's airborne dispersal of S. aureus without a surgical mask increased 40- fold; dispersal was significantly reduced when physician 4 wore a mask (P < or = 0.015). CONCLUSIONS: Physician 4 became a "cloud adult," analogous to the "cloud babies" described by Eichenwald and coworkers who shed S. aureus into the air in association with viral URIs. Airborne dispersal of S. aureus in association with a URI may be an important mechanism of transmission of S. aureus.

Perceived exertion during hypobaric hypoxia in low- and moderate-altitude natives.

Ratings of perceived exertion (RPE) were examined in six low- (LAN) and eight moderate- (MAN) altitude natives during exercise at their residence (home) altitude (366 m and 2,200 m, respectively) and 1-4 wk later following 2-d decompression to 4,270 m (447 mm Hg). Cardiorespiratory, plasma lactate, and differentiated RPE measures were obtained at exercise intensities representing 35, 55, 75, 85, and 100% VO2peak. In general, cardiorespiratory and plasma lactate values were similar in LAN and MAN at their residence altitudes and during hypobaric hypoxia. However, the decrease in VCO2 was greater (P < 0.05) in LAN than MAN. At their residence altitudes, both LAN and MAN reported local RPE values that were greater (P < 0.05) than central ratings at the moderate to high exercise intensities. At 447 mm Hg, central and local RPE were similar in LAN. However, there was a significant correlation between acute mountain sickness (AMS) symptoms and central RPE (r = 0.875) across the five exercise intensities in LAN. The differences between the central and local RPE noted in MAN during their residence testing also persisted at 447 mm Hg. Thus, differentiated ratings of perceived exertion were similar in MAN at their residence altitude and at 4,270 m, but not in LAN subjects. Several factors, including AMS, may have contributed to this group difference in the RPE response.

Exercise responses after short- and long-term residence at 2,200 meters.

Submaximal and maximal exercise responses were examined in persons (age, 19-30 years) residing at a moderate altitude for different periods of time. Long-term residents (LTR; 44 males, 11 females) had lived continuously between 1,830 and 2,200 m for 2 years or longer before testing. Short-term residents (STR; 22 males, 30 females), previously lowlanders, arrived at 2,200 m within 10 to 21 days before testing. Incremented tests on a motor-driven treadmill were performed until voluntary exhaustion. Cardiorespiratory measures and ratings of perceived exertion (RPE) were examined at 60% and 100% of maximal oxygen uptake (VO2max). With the exception of minute ventilation (VE), which was higher (p less than 0.05) in STR females, maximal responses were comparable in STR and LTR females. All maximal responses were similar in STR and LTR males. Both VE and RPE at 60% VO2max were significantly higher in STR males and females than in their LTR counterparts. Plasma lipid responses to the maximal exercise may indicate a greater contribution of the triglyceride pool of adipose tissue to fatty acid mobilization during exercise in the LTR compared to STR male subjects.

Aldosterone, cortisol, and electrolyte responses to hypobaric hypoxia in moderate-altitude natives.

Serum aldosterone, cortisol, and electrolyte concentration, and urinary aldosterone and electrolyte excretion responses were examined in seven low-altitude natives (LAN) (373 m or less, aged 19-25 yr) and nine moderate-altitude natives (MAN) (1,830-2,200 m, aged 19-23 yr) for 2 d at their own residence (home) altitude (PB 740 or 585 mm Hg, respectively) and later for 2 d during decompression at a simulated altitude of 4,270 m (PB 447 mm Hg). The LAN group demonstrated higher (p less than 0.05) serum cortisol concentrations and respiration rates, and lower (p less than 0.05) serum aldosterone and potassium, and urinary aldosterone, sodium, and potassium concentrations at certain times during decompression compared to their home responses. Moderate-altitude native responses, on the other hand, were generally unchanged. Manifestations of acute mountain sickness at PB 447 mm Hg were also significantly greater in the LAN group. Thus, it appears that the MAN subjects were influenced less by the drop in ambient oxygen tension associated with PB 447 mm Hg.

Adrenocortical responses to maximal exercise in moderate-altitude natives at 447 Torr.

Serum hydrocortisone and aldosterone (Aldo) responses to maximal exercise were examined in six low-altitude natives (LAN) (373 m or less, aged 19-25 yr) and eight moderate-altitude natives (MAN) (1,830-2,200 m, aged 19-23 yr) at their residence (home) altitudes (740 and 587 Torr, respectively) and later in a hypobaric chamber at a simulated altitude of 4,270 m (447 Torr). After 2 days at their respective residence altitude and in the chamber, each subject exercised to voluntary exhaustion on the bicycle ergometer. Fluid intake was similar in both groups at all testing locations. Preexercise 24-h urinary Aldo was lower in both groups at 447 Torr but only significantly reduced in the LAN group. In general, the changes in maximum exercise cardiorespiratory variables were twice as large in LAN as in MAN subjects going from residence altitude to 447 Torr. Both serum hydrocortisone and Aldo concentrations were increased (P less than 0.01) after exercise in both groups at residence altitude and 447 Torr. Aldo was lower (P less than 0.05) postexercise at 447 Torr than at residence altitude in both groups, but this decrease was more pronounced (P less than 0.01) in the LAN group. Thus it appears that high-altitude Aldo concentrations are more like resident altitude values in MAN than in LAN subjects.

Maximal exercise during hypobaric hypoxia (447 Torr) in moderate-altitude natives.

Six low-altitude natives (LAN) (373 m or less, aged 19-25 yr) and eight moderate-altitude natives (MAN) (1830-2200 m, aged 19-23 yr) were studied at both their residence (home) altitude (740 Torr and 587 Torr, respectively) and in a hypobaric chamber at a simulated altitude of 4270 m (447 Torr). Following a 2-d adaptation period, subjects performed an incremented test on the cycle ergometer until voluntary exhaustion. Significantly (P less than 0.05) greater differences in percent change of maximum exercise variables (total exercise time, exercise intensity, VO2, VCO2, VE/VO2 and HR) were noted in the LAN group than in the MAN group, going from their residence altitude to 447 Torr. The decrement in VO2max was 15% in the MAN group compared to 34% in the LAN group. The anaerobic threshold (% VO2max), estimated from VE BTPS measurements, was similar in both groups at residence altitude and at 447 Torr. In the morning prior to exercise testing at 447 Torr, LAN subjects reported greater (P less than 0.001) symptoms of acute mountain sickness (AMS) than MAN subjects. Our results indicate that, with respect to maximum exercise performance, moderate-altitude natives are at an advantage during early adaptation to hypobaric hypoxia.