Susceptibility of pneumococcal carriage isolates to penicillin provides a conservative estimate of susceptibility of invasive pneumococci

OBJECTIVE

Because of its practical importance for public health monitoring in developing countries, we aimed to determine whether susceptibility to penicillin of pneumococci isolated from the upper respiratory tract (URT) is representative of the susceptibility of pneumococci causing pneumonia in children.

METHOD

The serogroup distribution and minimum inhibitory concentration of penicillin for 56 and 90 isolates from blood and cerebrospinal fluid, respectively, were compared with those of 833 pneumococcal carriage isolates from Papua New Guinean children. These included 154 and 98 strains from bacteremic and nonbacteremic hospitalized patients with pneumonia, respectively, 350 from outpatients with respiratory infections and 176 and 55, respectively, from children in a community-based study who were healthy or sick with pneumonia.

RESULTS

Proportions of pneumococci intermediately resistant to penicillin were comparable in the URT and blood (60%) in 1985 through 1987 when serogroup distributions in the two sites were similar. However, penicillin resistance was higher in the URT (75%) than blood (44%) in 1980 through 1984 when the less frequently carried, less resistant serogroups (1 to 5, 7 to 12, 45 and 46) accounted for a high proportion of bacteremic strains.

CONCLUSIONS

URT isolates from any group of sick or healthy children could provide a conservative estimate of antimicrobial susceptibility of invasive strains and is a practical way of monitoring susceptibility as well as evaluating the continued effectiveness of standard antibiotic therapy. If there was cause for concern, it would then be necessary to examine invasive isolates.

The generation and subtraction of sensory expectations within cerebellum-like structures

The generation of expectations about sensory input and the subtraction of such expectations from actual input appear to be important features of sensory processing. This paper describes the generation of sensory expectations within cerebellum-like structures of four distinct groups of fishes: Mormyridae; Rajidae; Scorpaenidae; and Apteronotidae. These structures consist of a sheet-like array of principal cells. Apical dendrites of the principal cells extend out into a molecular layer where they are contacted by parallel fibers. The basilar regions of the arrays receive primary afferent input from octavolateral endorgans, i.e., electroreceptors, mechanical lateral line neuromasts, or eighth nerve endorgans. The parallel fibers in the molecular layer convey various types of information, including corollary discharge signals associated with motor commands, sensory information from other modalities such as proprioception, and descending input from higher stages of the sensory modality that is processed by the structure. Associations between the signals conveyed by the parallel fibers and particular patterns of sensory input to the basal layers lead to the generation of a negative image of expected sensory input within the principal cell array. Addition of this negative image to actual sensory input results in the subtraction of expected from actual input, allowing the unexpected or novel input to stand out more clearly. Intracellular recording indicates that the negative image is probably generated by means of anti-Hebbian synaptic plasticity at the parallel fiber to principal cell synapse. The results are remarkably similar in the different fishes and may generalize to cerebellum-like structures in other sensory systems and taxa.

Instantaneous analysis of aldehydes in biological fluids using a spray interface coupled to a mass spectrometer

A new interface coupled to a mass spectrometer was developed for the direct analysis of volatile organic compounds from small volumes of aqueous samples, including blood or tissue homogenates (St-Germain et al. 1995, Anal. Chem. 67:4536-4541). The greatest advantages of our system are minimal sample treatment, an instantaneous response time coupled with detection limits in the range of < 1 ppb for most compounds. For the analysis of low-molecular weight aldehydes, such as formaldehyde, acetaldehyde, propanal, and hexanal, lower detection limits were obtained when samples were converted to methoxime derivatives prior to injection. The detection limit for hexanal in water or Krebs-Ringer solution was 0.01 microM (10 pmol injected). The reproducibility of replicate injections was 4.4%. The usefulness of our system was illustrated by measuring aldehyde accumulation in peroxidized solutions of polyunsaturated fatty acids and rat tissue homogenates. Data confirmed that peroxidation of omega-3 fatty acids produces propanal, whereas omega-6 fatty acids form hexanal. Peroxidation of heart and brain homogenates formed predominantly propanal. However, the recovery of hexanal after sample treatment with methoxylamine depended on the derivatization time and temperature, suggesting that this aldehyde may form Schiff base linkages. These results show that spray extraction coupled to mass spectrometry provides a quick (< 1 min), clean and reproducible way to detect aldehydes produced from lipid peroxidation in aqueous samples.

In vivo hydroxylation of the neurotoxin, 1-methyl-4-phenylpyridinium, and the effect of monoamine oxidase inhibitors: electrospray-MS analysis of intra-striatal microdialysates

The neurotoxin 1-methyl-4-phenylpyridinium (MPP+) has been shown to increase hydroxyl radical formation in the striatum. The production of hydroxyl radicals correlates with the MPP(+)-driven dopamine release which presumably leads to increased metabolism via monoamine oxidase or increased dopamine autoxidation. Both processes result in enhanced production of hydrogen peroxide, which in the presence of iron(II) ions decomposes to the hydroxyl radical. Monoamine oxidase inhibitors decrease the production of hydroxyl radicals as measured by salicylate and 4-hydroxybenzoate trapping. As both MPP+ and monoamine oxidase inhibitors, such as deprenyl and MDL-72,974A, possess aromatic rings, hydroxyl radical adduct formation was investigated in vitro in defined Fenton systems and also in vivo using intra-striatal microdialysis to infuse MPP+ to rats pretreated systemically with either deprenyl or MDL-72,974A. Electrospray mass spectrometric analysis, using full-scan, fragment ion and constant neutral loss spectra, demonstrated ring hydroxylation of all three compounds in the Fenton systems. Spectral comparison of microdialysis samples with spectra from the Fenton reactions indicated the in vivo hydroxyl radical adduct attachment to MPP+, deprenyl and possibly MDL-72,974A.

Evaluation of sodium 4-hydroxybenzoate as an hydroxyl radical trap using gas chromatography-mass spectrometry and high-performance liquid chromatography with electrochemical detection

Molecular and tissue damage induced by reactive oxygen species is a serious consequence of the production of free radicals in biological systems. Biological markers produced by reactions with hydroxyl radicals are useful indices of free radical processes in vivo. In this respect, hydroxylation of aromatic compounds such as salicylate (2-hydroxybenzoate) has been used extensively as a measure of hydroxyl radical formation. 4-Hydroxybenzoate will also trap hydroxyl radicals with fewer of the complications for which salicylate has been criticized. We describe two sensitive and specific methods using gas chromatography-ion trap mass spectrometry and high-performance liquid chromatography with electrochemical detection for a number of these aromatic marker compounds in biological fluids. The use of an ion trap mass spectrometer provides enhanced sensitivity along with full mass spectral identification of the compounds of interest. 4-Hydroxybenzoate and salicylate were compared as hydroxyl radical traps (i) by determining relative hydroxyl radical trapping efficiencies in vitro, (ii) by measuring individual dihydroxybenzoate isomers in rat serum following intraperitoneal injection of either 2- or 4-hydroxybenzoate, and (iii) by comparing in vivo hydroxyl radical trapping using intrastriatal microdialysis in the rat. The techniques described have broad applications in the area of free radical biomedical research.

Reduced conception rates in dairy cattle associated with serological evidence of Leptospira interrogans serovar hardjo infection

Fertility data from 673 cows in five dairy herds with a moderate to high seroprevalence of microscopic agglutination titres (MAT) of > or = 1:10 against Leptospira interrogans serovar hardjo were collated to assess the relationship between pregnancy rates and antibody titres to serovar hardjo. A significant proportion of failures of conception (10 to 13 per cent, P < 0.001) were associated with MATs of 1:10 to 1:100; the overall pregnancy rate of the seronegative cows was 28.5 per cent higher (P < 0.001) than that of the cows with MATs of > or = 1:100. First service pregnancy rates showed a similar trend but the differences were significant (P < 0.05) only in cows with antibody titres > or = 1:30. An assessment of other possible risk factors for reduced pregnancy rates, such as lactation number and calving to first service interval, had no effect on the statistical results of the study or its conclusions.

Immunization with granulocyte-macrophage colony-stimulating factor-transduced, but not B7-1-transduced, lymphoma cells primes idiotype-specific T cells and generates potent systemic antitumor immunity

Recently, genetically modified tumor cell vaccines have been described for nonhematopoietic cancers in which the relevant Ags are unknown. Several of these cell-based vaccine strategies have been shown to induce T cell-mediated systemic antitumor immunity, either by enhancing the processing and presentation of tumor Ags by host APCs or by facilitating effective Ag presentation by the tumor vaccine itself. These strategies were compared in a model B cell lymphoma, a tumor derived from APCs, which have the inherent capacity to activate Ag-specific T cells. Eradication of pre-established systemic lymphoma was achieved following immunization with lymphoma cells engineered to produce granulocyte-macrophage (GM)-CSF, and to a lesser extent cells producing IL-4, whereas vaccination with lymphoma cells transfected with the genes encoding IL-2 or B7-1 had no effect. The systemic immunity generated by GM-CSF- or IL-4-transfected lymphoma required both CD4+ and CD8+ T cells. Previous immunotherapeutic strategies for the treatment of lymphoma have focused on the generation of Ab responses targeted to the unique Ig Id as a tumor-specific Ag. Anti-idiotypic Abs were undetectable in animals vaccinated with GM-CSF-transduced lymphoma cells. In contrast, such immunization did result in the induction of Id-specific T cell responses. This is the first demonstration that T cell responses specific for a native tumor Ag are generated by GM-CSF-transduced tumor cell-based vaccination, suggesting that B cell lymphoma may be a suitable disease for genetically modified tumor vaccine strategies.

Immunization with granulocyte-macrophage colony-stimulating factor-transduced, but not B7-1-transduced, lymphoma cells primes idiotype-specific T cells and generates potent systemic antitumor immunity

Recently, genetically modified tumor cell vaccines have been described for nonhematopoietic cancers in which the relevant Ags are unknown. Several of these cell-based vaccine strategies have been shown to induce T cell-mediated systemic antitumor immunity, either by enhancing the processing and presentation of tumor Ags by host APCs or by facilitating effective Ag presentation by the tumor vaccine itself. These strategies were compared in a model B cell lymphoma, a tumor derived from APCs, which have the inherent capacity to activate Ag-specific T cells. Eradication of pre-established systemic lymphoma was achieved following immunization with lymphoma cells engineered to produce granulocyte-macrophage (GM)-CSF, and to a lesser extent cells producing IL-4, whereas vaccination with lymphoma cells transfected with the genes encoding IL-2 or B7-1 had no effect. The systemic immunity generated by GM-CSF- or IL-4-transfected lymphoma required both CD4+ and CD8+ T cells. Previous immunotherapeutic strategies for the treatment of lymphoma have focused on the generation of Ab responses targeted to the unique Ig Id as a tumor-specific Ag. Anti-idiotypic Abs were undetectable in animals vaccinated with GM-CSF-transduced lymphoma cells. In contrast, such immunization did result in the induction of Id-specific T cell responses. This is the first demonstration that T cell responses specific for a native tumor Ag are generated by GM-CSF-transduced tumor cell-based vaccination, suggesting that B cell lymphoma may be a suitable disease for genetically modified tumor vaccine strategies.

A case-control study of diet in newly diagnosed NIDDM in the Wanigela people of Papua New Guinea

OBJECTIVE--To study the association between diet and newly diagnosed NIDDM in the Wanigela people of Papua New Guinea, a population with an extraordinary susceptibility for NIDDM. RESEARCH DESIGN AND METHODS--We performed a case-control study of Wanigela people from an urban settlement (Koki). Case patients (n = 145) were asymptomatic subjects in whom NIDDM was newly diagnosed using a 2-h 75-g oral glucose tolerance test. Control subjects with glucose tolerance (n = 140) were group-matched on the basis of age and sex. A detailed food frequency questionnaire was used to determine energy and nutrient intakes. Nutrient intakes were compared directly and after calculation of residuals to correct for energy intake. Odds ratios for NIDDM were computed in relation to total energy and specific nutrient intakes, adjusting for age, sex, BMI, waist-to-hip ratio, and physical activity. RESULTS--There were no differences between case patients and control subjects in mean values of total energy-adjusted nutrient intakes. In logistic regression models, neither total energy nor any specific nutrients were associated with increased risk of NIDDM. When models were repeated with nutrients categorized by textiles, there were marginally significant associations with intakes of fiber (positive) and cholesterol, protein, and sugar (negative). CONCLUSIONS--This study does not support the hypothesis that saturated fat is an independent risk factor for NIDDM. The weak associations of intakes of fiber and cholesterol with newly diagnosed NIDDM were in the opposite directions to those expected and are probably due to chance. Relative homogeneity of diet within a community, such as that found in Koki, makes it difficult to demonstrate risk factor-disease associations. However, changes in diet and reduced levels of physical activity accompanying urbanization undoubtedly contribute to the high prevalence of obesity observed in this community, and hence diet is likely to contribute to NIDDM risk at least by indirect means.

Hindbrain signal processing in the lateral line system of the dwarf scorpionfish Scopeana papillosus

Recordings were made from primary afferent fibres and secondary projection neurones (crest cells) in the mechanosensory lateral line system of the dwarf scorpionfish. Crest cells were identified by antidromic stimulation from the contralateral midbrain. Differences between primary afferent fibre and crest cell response characteristics are indicative of signal processing by the neuronal circuitry of the medial octavolateralis nucleus. There are a number of differences between primary afferent fibres and crest cells. Primary afferents have relatively high levels of spontaneous activity (mean close to 40 impulses s-1) and many of them are strongly modulated by ventilation. By contrast, crest cells have a much lower rate of spontaneous activity that is not obviously modulated by ventilation. Primary afferents show a simple tonic response to a maintained stimulus, whereas crest cells show a variety of temporal response properties, but in general show a phasic/tonic response to the same prolonged stimulus. Afferents are most sensitive to frequencies of stimulation around 100 Hz; in contrast, crest cells show a strong suppression of activity at this frequency. Crest cells are most responsive around 50 Hz. These afferent/secondary comparisons show similarities with those reported for allied electrosensory and auditory pathways.

Presence of antigen and antibodies in serum and genital discharges of cows from dairy herds naturally infected with Leptospira interrogans serovar hardjo

Samples of cervico-vaginal mucus from 163 bulling cows (group 1) and post calving discharges from 59 newly calved cows (group 2) in five dairy herds naturally infected with Leptospira interrogans serovar hardjo were examined for the presence of antigen and IgG and IgA antibodies by using two ELISA systems which were protein or carbohydrate based. Corresponding serum samples were examined for systemic immune responses by using a microscopic agglutination test (MAT) and IgG-ELISA tests. Antigen was detected by direct immunofluorescence in six of the 163 samples of cervico-vaginal mucus. Both IgG and IgA antibodies were detected by ELISA in the genital discharges with a prevalence much higher than that obtained by the MAT but lower than that observed with the serum IgG-ELISA. Combining both groups, none of the MAT-positive cattle was negative by serum-ELISA. By using the protein or carbohydrate fraction serum IgG-ELISA assays, respectively, 29 or 41 per cent of the MAT-negative cows were positive at a titre of at least 1:40. Similarly, eight or 23 samples (10 or 27 per cent) had titres of at least 1:20 in the genital discharge ELISA for IgG and IgA antibodies, respectively. The serum IgG-ELISA was the most efficient in detecting hardjo antibodies, but in group 2 the IgG- and IgA-ELISA of the post calving discharge proved to be equally effective.

Presence of antigen and antibodies in serum and genital discharges of heifers after experimental intrauterine inoculation with Leptospira interrogans serovar hardjo

The excretion of Leptospira interrogans serovar hardjo in cervico-vaginal mucus (CVM) or urine and the local and systemic immune responses to the organism were monitored in eight susceptible heifers after intrauterine inoculation while six similar heifers served as controls. All the heifers were inseminated at the subsequent oestrous periods. The overall percentage pregnancy rate (the number of pregnancies divided by the total number of inseminations) was lower in the infected heifers than in the controls though not significantly (33.3 v 50.0 per cent). Leptospires were detected, in either the urine or the CVM of six of the eight infected heifers during the study period of 15 weeks, either by direct immunofluorescence or dark ground microscopy; the bacteria did not grow in culture from any of the CVM samples. The control heifers remained free from evidence of infection. In the infected heifers, mean titres of at least 1:100 in a microscopic agglutination test were maintained for one to two weeks before declining to 1:10 to 1:30, whereas in serum IgG-ELISA tests (developed by using either protein or carbohydrate antigens), antibody titres of at least 1:100 were maintained throughout the study. During oestrous periods, IgA antibodies were detected more frequently in CVM with titres which were usually higher than the titres of IgG.

Hydroxylation of aromatic compounds as indices of hydroxyl radical production: a cautionary note revisited

While setting up an intracerebral microdialysis system to estimate the extent of oxidative stress induced by the neurotoxin, N-methylphenylpyridinium ion (MPP+), we encountered a problem in the use of hydroxybenzoic acids as traps of hydroxyl radicals. Using either 2-hydroxybenzoate (salicylate) or 4-hydroxybenzoate as trapping agents, we observed a nonspecific, that is, nontissue derived, production of hydroxyl radicals as measured by the hydroxylation products, 2,3- and 2,5-dihydroxybenzoate from 2-hydroxybenzoate and 3,4-dihydroxybenzoate from 4-hydroxybenzoate. This production of dihydroxybenzoates was 10 times that expected due to the administration of MPP+, thus making it impossible to interpret our results. Careful investigation of the various components of the microdialysis system indicated that contact of the microdialysate with metal surfaces resulted in dihydroxybenzoic acid formation. These results should serve as a reminder to perform stringent tests of the experimental system prior to experiments with biological tissues to evaluate the contribution of hydroxyl radical production from nonbiological sources. Therefore, along with the possibility of enzymatic production of dihydroxybenzoates, artefactual production by components of the experimental apparatus must be considered before assuming that one is measuring hydroxyl radical production by a biological system.

Environmental design, work, and well being: managing occupational stress through changes in the workplace environment

The physical environment can be an important contributor to occupational stress. Factors that contribute to stress and other negative outcomes include: lack of control over the environment, distractions from coworkers, lack of privacy, noise, crowding, and environmental deprivations (such as lack of windows and aesthetic impoverishment). The design of "salutogenic" environments requires not only the elimination of negative stress inducing features, but also the addition of environmental enhancements, including such factors as increased personal control, contact with nature and daylight, aesthetically pleasing spaces, and spaces for relaxation alone or with others. Salutogenic environments also take into consideration positive psychosocial "fit," as well as functional fit between people and environments. At the heart of the current interest in the work environment are two major concerns: organizational productivity and employee well being.

A method for isolation and partial purification of Trichinella spiralis nurse cells

Invasion of vertebrate muscle cells by larvae of Trichinella spiralis is accompanied by redifferentiation of the host myofiber into a novel structure called the nurse cell. The nurse cell protects and nurtures the enclosed parasite during its long stay in host muscle. It is anatomically independent of the surrounding uninfected muscle cells and can be isolated from host tissue by mechanical or enzymatic means. Current methods employed for this purpose have yielded only small numbers of nurse cells. An apparatus designed to isolate large numbers of nurse cells and a method for removal of all free larvae and most host muscle debris is described. Homogenization and trypsin digestion of muscle tissue was followed by passage of muscle/parasite suspensions maintained at 37 C through a jacketed glass column fitted with a 40-mesh stainless steel screen at the top and a Nitex screen with 150-microns-diameter pores at the bottom. Nurse cells were retained by the Nitex screen. Density gradient centrifugation using Percoll removed all free larvae and most contaminating muscle debris from nurse cell suspensions. The large quantities of nurse cells made available by this method will allow evaluation of the molecular biology, nutrition, biochemistry, and metabolism of the enclosed parasite and of the Trichinella-modified host muscle cell.

Cryptococcal pneumonia simulating chronic eosinophilic pneumonia

We report two cases of cryptococcal pneumonia in which the roentgenographic picture closely mimicked that for chronic eosinophilic pneumonia. Caution in use of corticosteriods based on this roentgenographic pattern is stressed.

Function and evolution of superficial neuromasts in an Antarctic notothenioid fish

Extracellular recording techniques were used to measure frequency response functions of anterior and posterior lateral line nerve fibers innervating superficial neuromasts at five different locations on the head and trunk of an antarctic notothenioid fish, Trematomus bernacchii. Scanning electron microscopy was used to measure neuromast size according to location. Fibers innervating neuromasts from all locations were similar in showing equal responsiveness in the 10-30 Hz range to equal pk-pk velocity levels of a sinusoidally vibrating sphere. The mean cut-off frequency (CF) at which responsiveness declined to 50% of maximum was 46 Hz for all fibers combined. Superficial neuromasts located on the ventral trunk line were three to six times larger in surface area than most other neuromasts. The mean CF for fibers innervating these large neuromasts was 7-18 Hz lower than mean CF's corresponding to other superficial neuromast locations, but small differences in mean CF's were not consistently related to neuromast size. It is argued that fiber responses from different superficial neuromasts are more similar than dissimilar and that the evolution of large superficial neuromasts on the ventral trunk line is linked to a general paedomorphic trend among notothenioid fishes that may be essentially non-adaptive for the lateral line.

Form and function relationships in lateral line systems: comparative data from six species of Antarctic notothenioid fish

The structure and physiology of the anterior lateral line canal systems were studied in six species of fish belonging to two different families within the suborder of antarctic fish Notothenioidei. Many of the canals within the species belonging to the genus Trematomus are relatively straight sided tubes with diameters around 0.4 mm. Some of the canals in Trematomus, and most of the canals in the icefishes (family Channichthyidae) are more complex. Relatively small pores lead into large tubules, the walls of which appear partially membranous, and the canals not much more than constrictions between adjacent tubules. Dissostichus mawsoni, a large species, has canals with distinctive wide and narrow sections, 1.8 mm and 0.48 mm, respectively. Despite these morphological differences the frequency response characteristics of anterior lateral line units are remarkably similar in all six species. In the case of D. mawsoni, this functional similarity results from narrow sections of the canals, which provide the viscous resistance to flow that preserves the mechanical filtering properties of the canal despite the huge size difference between D. mawsoni and the other species. It is argued that the most appropriate way to view canals is as high pass filters which attenuate lower frequencies, and that this effect is best illustrated by comparing the frequency response characteristics of superficial and canal neuromasts using a sinusoidal stimulus that has a constant peak-to-peak velocity. The functional contribution of canals is to attenuate low frequencies and improve the signal-to-noise ratio for biologically important signals in the presence of low frequency noise produced, for example, by the animal's own movements.

Positive and negative regulatory regions control the spatial distribution of polygalacturonase transcription in tomato fruit pericarp

The tomato fruit consists of a thick, fleshy pericarp composed predominantly of highly vacuolated parenchymatous cells, which surrounds the seeds. During ripening, the activation of gene expression results in dramatic biochemical and physiological changes in the pericarp. The polygalacturonase (PG) gene, unlike many fruit ripening-induced genes, is not activated by the increase in ethylene hormone concentration associated with the onset of ripening. To investigate ethylene concentration-independent gene transcription in ripe tomato fruit, we analyzed the expression of chimeric PG promoter-beta-glucuronidase (GUS) reporter gene fusions in transgenic tomato plants. We determined that a 1.4-kb PG promoter directs ripening-regulated transcription in outer pericarp but not in inner pericarp cells, with a sharp boundary of PG promoter activity located midway through the pericarp. Promoter deletion analysis indicated that a minimum of three promoter regions influence the spatial regulation of PG transcription. A positive regulatory region from -231 to -134 promotes gene transcription in the outer pericarp of ripe fruit. A second positive regulatory region from -806 to -443 extends gene activity to the inner pericarp. However, a negative regulatory region from -1411 to -1150 inhibits gene transcription in the inner pericarp. DNase I footprint analysis showed that nuclear proteins in unripe and ripe fruit interact with DNA sequences within each of these three regulatory regions. Thus, temporal and spatial control of PG transcription is mediated by the interaction of negative and positive regulatory promoter elements, resulting in gene activity in the outer pericarp but not the inner pericarp of ripe tomato fruit. The expression pattern of PG suggests that, although they are morphologically similar, there is a fundamental difference between the parenchymatous cells within the inner and outer pericarp.

Levels of anti-pneumococcal antibodies in young children in Papua New Guinea

Anti-pneumococcal polysaccharide antibody (anti-PPS) levels were measured in 153 serum samples collected from children aged between 2 and 47 months living in the highlands of Papua New Guinea (PNG). Fifty-seven of the samples were collected during acute episodes of lower respiratory tract infection (ALRI). Total IgA and IgG increased steadily with age; however, no association was found between the levels of these antibodies and the health status of the child. Total IgM levels showed little relationship to the age of the child but under 12 months of age levels were somewhat higher on average in children with pneumonia. For most of eight pneumococcal serotypes tested, specific IgG levels were found to decline rapidly in the first 6-8 months, reaching a minimum at approximately 12 months of age. Serotype 3 was exceptional in having very low titres in the youngest children. A separate analysis of 24 cord sera suggested that antibodies to this serotype do not usually cross the placenta in PNG. Children with pneumonia tended to have lower levels of specific IgG than healthy controls of the same age. Specific anti-PPS IgA levels were found to increase steadily with age, but were not associated with health status.

Acquisition and invasiveness of different serotypes of Streptococcus pneumoniae in young children

Rates of acquisition and mean duration of nasal carriage of different serotypes of Streptococcus pneumoniae have been estimated by fitting a stochastic model to longitudinal carriage data in children from Papua New Guinea. Immunogenicity and two indices of relative invasiveness were determined for each serotype. Immunogenic serotypes were less frequently acquired and were carried for shorter periods, but no relationship between immunogenicity and invasiveness was apparent using either index of invasiveness. Frequent invasion was associated with a high acquisition rate and high frequency and prolonged duration of carriage. Carriage studies can provide a broad indication of which serotypes cause invasive disease but not the proportion of disease due to individual serotypes; some serotypes which cause invasive disease (e.g. serotype 46) are not found even in extensive carriage studies. The antibiotic resistance of carriage organisms, however, does approximate the resistance patterns of invasive organisms and thus may be used to monitor changing patterns of antimicrobial susceptibility in the community.

Identification of an ethylene-responsive region in the promoter of a fruit ripening gene

Transcription of the E4 gene is controlled by an increase in ethylene concentration during tomato fruit ripening. To investigate the molecular basis for ethylene regulation, we have examined the E4 promoter to identify cis elements and trans-acting factors that are involved in E4 gene expression. In transgenic tomato plants a chimeric gene construct containing a 1.4-kilobase E4 promoter fused to a beta-glucuronidase reporter gene is rapidly induced by ethylene in ripening fruit. Deletion of E4 promoter sequences to 193 base pairs reduces the level of GUS activity but does not affect ethylene induction. Transient expression of E4 promoter-luciferase chimeric gene constructs containing various deletions, introduced into tomato fruit pericarp by particle bombardment, indicates that a positive ethylene-responsive region is localized between nucleotides -161 and -85 relative to the transcription start site. DNase I footprint analysis shows that a nuclear factor in unripe fruit interacts specifically with sequences in this element, from -142 to -110, which are required for the ethylene response. The DNase I footprint of this factor is reduced in ethylene-treated unripe fruit and undetectable in ripe fruit. Based on the correlation of a nuclear factor binding site with promoter sequences required for ethylene induction, we propose that this in vitro DNA-binding activity may represent a factor that is involved in ethylene-regulated E4 gene expression.

Antigenuria in healthy Papua New Guinean children with nasal Haemophilus influenzae type b carriage

In 100 healthy children under the age of 3 years living in the vicinity of Goroka, Papua New Guinea, the nares were cultured for Haemophilus influenzae type b (Hib), and a urine sample was obtained for measurement of Hib polysaccharide (PS) by ELISA. Hib carriage was detected in nine children and Hib PS was detected in the urine of 11. Hib PS was found in seven of nine Hib nasal carriers compared with four of 91 healthy children without Hib in their nares (p < 0.001). The range of urine antigen concentrations in the two groups was similar (0.6 to 2.7 ng/ml). The relative risk of antigenuria in the carriers, compared with the children with negative nares cultures, was 58 (95% confidence interval, 10.5-324). These data extend previous observations from Hib carriers studied in the United States and show that Hib carriage in children from a developing country is associated with antigenuria. Further studies are needed to determine whether carriers and patients can be differentiated by differences in the magnitude of the concentration of Hib PS excreted in urine.

A case of spontaneous hypothermia

It is important to recognise any condition, however rare, which can be cured. We report a case of chronic hypothermia and its dramatic response to treatment.

Fibers innervating different parts of the lateral line system of an Antarctic notothenioid, Trematomus bernacchii, have similar frequency responses, despite large variation in the peripheral morphology

Regional differences in the architecture and size of lateral line canals and neuromasts were measured in an Antarctic fish, Trematomus bernacchii, and the data were used in models of canal and cupular mechanics to predict the frequency response of these two peripheral structures. These modeled predictions were then compared to frequency response functions measured with single unit recording techniques from anterior and posterior lateral line fibers innervating different canals on the head and trunk of fish of various sizes. Despite large variations in the peripheral morphology of head and trunk canals in fish of different sizes, lateral line fibers were relatively homogeneous in their frequency response properties. In response to stimuli of equal pk-pk acceleration levels, all canal neuromast fibers responded with equal and maximum responsiveness in the 10-45 Hz range, after which responsiveness fell off at about 18 dB/octave. Whereas the biomechanical models of cupular and canal responsiveness predicted the region of equal and maximum responsiveness in the 10-45 Hz range, they did not predict the high frequency cutoff nor the slope. Rather, these models predicted responsiveness out to at least 540 Hz, and a high frequency slope of 12 dB/octave. In terms of the frequency response of peripheral fibers, we conclude that (1) there can be considerable morphological variability, with little consequence for function, as long as some minimum standards for maintaining constant acceleration responsiveness in the 10-45 Hz range are met, and (2) there must be additional filters between the cupula and primary afferent fibers.

Physiological characterization of lateral line function in the Antarctic fish Trematomus bernacchii

The Antarctic notothenioids are a monophyletic radiation of fishes that have evolved under conditions of low light and cold, where non-visual sensory systems, such as the mechanosensory lateral line system, would be of importance. As part of a study of the structure and function of the mechanosensory lateral line system in these fishes we systematically characterized the function of the anterior lateral line system in one of the common benthic species, Trematomus bernacchii. Frequency-response and threshold-tuning curve methods yield similar functional characterizations of single afferent fibre responses to vibrational stimulation. Curve fitting of generalized transfer function to frequency-response curves allows an objective splitting of responses into velocity and acceleration sensitive populations thought to correspond to superficial and canal neuromasts, respectively. Both response types are characterized by a low-pass frequency-response curve, with a relatively low upper frequency cut-off when compared with data from temperate species. The sensitivity of the lateral line system of T. bernacchii is comparable to that of the mottled sculpin Cottus bairdi.

The bacteriology of acute pneumonia and meningitis in children in Papua New Guinea: assumptions, facts and technical strategies

Acute respiratory infections in children aged less than 5 years in the Eastern Highlands of Papua New Guinea were investigated bacteriologically for 10 years from November 1978. Haemophilus influenzae and Streptococcus pneumoniae were responsible for 73% of all bacteria cultured from lung aspirate (83 samples), 85.5% from blood (1024 samples) and 92% from cerebrospinal fluid (155 samples). Nonencapsulated H. influenzae was carried by up to 90% of children and was the predominant haemophilus type cultured from lung tissue. Mixed infections of the lung with two types of H. influenzae (8 cases) and both H. influenzae and S. pneumoniae (18 cases), commonly together with other organisms of questionable pathogenicity, reflected the proximity of this organ to the upper respiratory tract. Serotype b accounted for 62% and 82% of H. influenzae isolated from bacteraemic pneumonia and meningitis cases, respectively. Polymicrobic bacteraemic pneumonia occurred in 16 children. Both H. influenzae and S. pneumoniae establish dense, unregulated long-term colonization in the nasopharynx during the neonatal period. Each inhibit autochthonous microflora by mechanisms that are currently unclear. Infections with two or more types occur in 30% (S. pneumoniae) and 60% (H. influenzae) of carriage-positive children. 70-75% of H. influenzae and S. pneumoniae isolates from blood concomitantly colonize the upper respiratory tract. Intense exposure of Papua New Guinean children to penicillin at all levels of health care since the 1940s has resulted in widespread relative resistance among pneumococci to this antibiotic. Resistant strains are now found in 32 serotypes, and in children penicillin resistance is present in 75% of all carriage strains and 52% and 22% of blood and cerebrospinal fluid isolates, respectively. Penicillin-susceptible and resistant pneumococcal serotypes commonly coexist in multiply populated carriage sites. Resistance to betalactam antibiotics is rare among H. influenzae strains and resistance has not been detected in either H. influenzae or S. pneumoniae to chloramphenicol, erythromycin, tetracycline or cotrimoxazole. It should not be assumed that the technology of respiratory bacteriology as it is practised in developed countries can be transferred to the third world for utilization in paediatric aetiology and carriage studies. Respiratory bacteriology strategies as they evolved in Goroka were subject to diverse influences. The type distribution of the major causative agents defied fashionable beliefs, generated the need for more precise epidemiological differentiation and, by virtue of their carriage density, cultural properties and response to commonly used antibiotics, required the introduction or development of compatible diagnostic procedures.

Leptospires isolated from toads and frogs on the Island of Barbados

Four pathogenic strains of leptospires were isolated from the kidneys of toads (Bufo marinus) and seven from frogs (Eleutherodactylus johnstonei). Isolates from two toads and one frog belonged to serovar bim, the causative agent of most cases of severe leptospirosis on Barbados. The other eight strains belonged to a new serovar within the Australis serogroup. The name bajan is proposed for this new serovar of Leptospira interrogans.

Antimicrobial susceptibility patterns of Haemophilus isolates from children in eleven developing nations. BOSTID Haemophilus Susceptibility Study Group

The antimicrobial susceptibilities of 426 isolates of Haemophilus species, which were collected as part of a worldwide study of the etiology of acute respiratory disease in children in selected developing countries, were determined. Eleven antibiotics were tested using the recently described Haemophilus Test Medium. There was a low prevalence of antibiotic resistance; 6% of strains were resistant to ampicillin, and 1.6% were resistant to chloramphenicol. Strains resistant to both ampicillin and chloramphenicol were recovered only from Thailand. Susceptibility to penicillin G was also determined; the minimum inhibitory concentrations for penicillin and ampicillin were concordant within one 2-fold dilution in 97% of the isolates. Thus, Haemophilus isolates were as susceptible to penicillin G as they were to ampicillin, and penicillin resistance was infrequent overall. These data provide support for the current protocols for the management of acute respiratory infections in children in developing countries, in which penicillin G is a first-line agent.

Multiple colonization of the upper respiratory tract of Papua New Guinea children with Haemophilus influenzae and Streptococcus pneumoniae

Nasal secretions from Papua New Guinea children were cultured using selective agents, to determine the prevalence of multiple colonization for both S. pneumoniae and H. influenzae. 29.5% of 156 and 53% of 93 carriage positive subjects harbored more than one type of S. pneumoniae and H. influenzae respectively. Of 95 strains of pneumococci isolated from multiply colonized children, 40% were relatively resistant to benzylpenicillin. In more than one half of the children in this group both penicillin sensitive and resistant serotypes coexisted. Significantly more penicillin resistant pneumococci were isolated from children with ready access to primary and regional health care services. Among H. influenzae the prevalence of multiple isolations due to nonencapsulated variants only, and encapsulated plus nonencapsulated organisms was similar. The commonest biotypes were types I, II, III and V, and each was similarly associated with multiple carriage.

Penicillin-resistant Streptococcus pneumoniae and other nasal bacteria among children in remote areas of the fringe highlands of Papua New Guinea

The nasal bacteriology of children in two areas of the western Schrader Range was studied. One area, served by an aid post since 1976, was compared with the other, which received its first medical care in 1984. Significant differences in the amount of resistance to penicillin were found, but not in the direction expected. These anomalous findings are interpreted in light of the particular histories of the groups involved, suggesting the transmission of resistant strains through contact among children.

Low plasma beta-endorphin in post-traumatic stress disorder

We compared serum cortisol, ACTH and plasma beta-endorphin in 21 Post-Traumatic Stress Disorder patients and 20 controls. Although we found no important disturbance in diurnal rhythms, the PTSD patients had significantly higher A.M. serum cortisols compared with controls. Both A.M. and P.M. plasma beta-endorphins in PTSD patients were significantly lower compared with controls. These data suggest that plasma beta-endorphin may be a marker for PTSD and that chronic endogenous opioid depletion may play a role in the pathogenesis and perpetuation of this disorder.

Isolation of Fusobacterium nucleatum and electron microscopic observations of spirochetes from tropical skin ulcers in Papua New Guinea

Tropical ulcer is a disabling condition of the lower leg affecting mainly young adults and older children. Microscopic observations of lesion material have shown fusiform bacilli and spirochetes. We used anaerobic culture techniques to isolate and identify these fusiform bacilli. Electron microscopic (EM) studies were performed to characterize the spirochetes. Material collected on swabs was used to inoculate pre-reduced media and to prepare smears for gram staining; the swabs were placed in fixative for EM study. After incubation, colonies containing fusiform bacilli were subcultured. The anaerobic gram-negative fusiform isolates were identified as Fusobacterium nucleatum using biochemical reactions, hemagglutination testing, and reaction of antigen preparations of the isolates and ATCC strains in serological tests with rabbit antisera. EM observations of negatively stained spirochetes revealed an 8-16-8 periplasmic flagellar arrangement. F. nucleatum and spirochetes may participate in the pathogenesis of this polymicrobic infection.