Restructuring health care in the Third World.
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Biomedical subjects
Publications and source records attributed to M Carpenter.
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Urinary excretion of cAMP and cGMP was studied in nine normal and 15 asthmatic children. Bronchial lability was studied with a treadmill running test and atopy with serum IgE and skin prick tests. A circadian rhythm was found in both groups for cAMP and cGMP excretion. Cyclic GMP levels were higher in the asthma group, the difference reaching statistical significance around the time of the exercise challenge test. The fall in PEF induced by exercise showed a significant negative correlation with urinary cAMP responsiveness to isoproterenol inhalation. Exercise-induced bronchial lability correlated with 24-h cGMP excretion. High cGMP and low cAMP levels at night could be connected with nighttime exacerbations of symptoms. It is suggested that cGMP might have a more important role in asthma, than previously assumed.
Pseudomonas aeruginosa strains PAO and PAK bear polar pili which are flexible filaments having a diameter of 6 nm and an average length of 2500 nm. Both types of pili are retractile and promote infection by a number of bacteriophages. The present communication describes the partial biochemical characterization of PAO pili isolated from a multipiliated nonretractile mutant of PAO. The observed properties are compared to those of PAK pili which were characterized previously. PAO pili were found to contain a single polypeptide subunit of 18 700 daltons. This is similar to PAK pili which contain a single polypeptide of 18 100 daltons. The amino acid composition of PAO pilin was also similar to that of PAK pilin. Neither protein contained phosphate or carbohydrate residues and both were found to contain N-methylphenylalanine at the amino terminus. Sequencing of 20 amino acid residues at the amino terminal end of PAO pilin revealed the sequence to be identical with that of PAK pilin, while tryptic peptide analyses of PAO and PAK pilin indicated that the two proteins probably contain a number of homologous regions within the polypeptide. It was concluded that PAO and PAK pili were closely related structures.
The effect of 3 wk heat exposure (Ta 34 degrees C) on intestinal weight and intestinal absorption of D-glucose and D-galactose in vitro was examined in the rat. Intestinal dry weight was reduced with heat exposure compared to both ad libitum and pair-fed animals at Ta 22 degrees C. Intestinal tissue water was elevated after pair feeding but not heat exposure; extracellular (inulin) space was similar in the three groups. Mucosal uptake of glucose per gram wet weight in an everted sac preparation was unchanged compared to pair-fed animals, but serosal transfer was increased. Intestinal metabolism of glucose was decreased with heat exposure. Galactose accumulation with 30 min incubation was increased in intestinal rings from both heat-exposed and pair-fed animals. This increase is likely to be related to the reduction in ring size present in the groups with reduced food intake. Vmax and apparent Km for galactose transport were unchanged. Our results indicate that despite a reduction in intestinal weight following heat exposure, the ability of the intestine to transport hexoses per gram remains relatively stable. Alterations of hexose transport appear to be related to altered glucose metabolism and not altered transport capacity. Differences in intestinal weight and glucose utilization between pair-fed and heat-exposed animals suggest that the intestinal response to chronic heat exposure is not solely a function at the amount of food consumed. However, the alteration of more than one variable in pair feeding makes interpretation complex.
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The amino-terminal amino acid sequence of the pili protein from Pseudomonas aeruginosa K pili is presented. The sequence is compared with those reported by others for pilin obtained from Neisseria gonorrhoeae and Moraxella nonlique-faciens. All three sequences are highly homologous, contain only two hydrophilic residues in the first 22 positions, and contain an unusual amino acid, N-monomethylphenylalanine, at the amino terminus.
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An adult with a unilateral precipitous severe high-frequency hearing loss displayed a selective auditory temporal resolution deficit in the poorer ear, despite excellent word recognition ability in quiet bilaterally. Word recognition performance was inferior in interrupted noise, reverberation, and time-compression conditions when stimuli were presented to the hearing-impaired ear and compared with performance for stimuli presented to the normal-hearing ear or that of normal-hearing listeners. It was suggested that a restricted listening bandwidth was responsible for the performance decrement on the tasks involving temporal resolution. This case illustrates the importance of employing temporal resolution tasks in an audiologic test battery. Such assessment tools may reveal deficits that otherwise may go unnoticed in light of excellent word recognition in quiet.
PURPOSE: To study the measurement of intraocular pressure after implantation of Intacs (ICRS) intrastromal corneal ring segment, a device that is positioned circumferentially in the peripheral corneal stroma to correct myopia. The device changes the corneal curvature by shortening arc length. Since the ring segments are made of polymethylmethacrylate, this may cause localized changes in corneal elasticity so intraocular pressure measurement may be affected. METHODS: We measured the intraocular pressure of 12 eyes in which the ICRS had been in place longer than 6 months. We used Goldmann applanation and Tono-Pen tonometers over the central corneal and the paracentral corneal areas. We also measured the intraocular pressure with the Tono-Pen applanated directly over the intrastromal corneal ring segments. RESULTS: The resulting intraocular pressure measurements were similar for the Tono-Pen tonometer readings over the central cornea, paracentral cornea, and the Goldmann applanation tonometer readings over the central cornea (P < .01). Our measurements using the Goldmann applanation tonometer on the paracentral corneal area showed artificially elevated intraocular pressure in the 40 to 60 mmHg range. We were not able to obtain consistent results when we measured the intraocular pressure using the Tono-Pen on the corneal area directly overlying the intrastromal corneal ring segment implants. CONCLUSION: Consistent intraocular pressure measurements on eyes with the ICRS can be obtained with the Goldmann applanation tonometer over the central corneal area or with the Tono-Pen tonometer over the central or paracentral corneal areas.
The mismatch negativity (MMN) is an event-related potential that involves a negative voltage shift of baseline electroencephalographic (EEG) activity in the approximate latency window of the N1 and P2 cortical potentials in response to new or novel sounds. The MMN is present at birth and has been hypothesized to serve as an automatic preconscious detector of changes in the auditory environment. Research paradigms used to extract the MMN response from EEG activity have a potential problem related to neuronal refractoriness or recovery. Both N1 and P2 are known to increase in amplitude with longer interstimulus intervals (ISIs). The MMN extraction procedures involve mathematical subtraction of waveforms elicited by standard sounds (with short ISIs) from those recorded to rare deviant sounds (with longer ISIs). Any ISI-dependent amplitude changes in N1 and/or P2 could therefore alter the morphology of the resulting difference wave and lead to misinterpretation of the nature of the underlying MMN generators. We tested 12 young females and found that the MMN can be influenced by ISI-dependent refractory effects that may modify the waveform morphology. This has important clinical implications since the MMN is being investigated as an assessment tool.
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