In-shoe Plantar Pressure Distribution in Nonneuropathic Type 2 Diabetic Patients in Singapore.

BACKGROUND: We sought to establish the in-shoe plantar pressure distribution during normal level walking in type 2 diabetic patients of Chinese, Indian, and Malay descent without clinical evidence of peripheral neuropathy. METHODS: Thirty-five patients with type 2 diabetes mellitus without loss of tactile sensation and foot deformities and 38 nondiabetic individuals in a control group had in-shoe plantar pressures collected. Maximum peak pressure and peak pressure-time integral of each foot were analyzed as separate variables and were masked into 13 areas. Differences in pressure variables were assessed by analysis of covariance, adjusting for relevant covariates at the 95% confidence interval. RESULTS: No significant differences were noted in maximum peak pressures after adjusting for sex, race, age, height, and body mass. However, patients with diabetes mellitus had significantly higher mean ± SD pressure-time integrals at the right whole foot (309.50 ± 144.17 kPa versus 224.06 ± 141.70 kPa, P < .05) and first metatarsal (198.65 ± 138.27 kPa versus 121.54 ± 135.91 kPa, P < .05) masked areas than did those in the control group after adjustment. CONCLUSIONS: Patients without clinical observable signs of foot deformity (implying absence of motor neuropathy) and sensory neuropathy had similar in-shoe maximum peak pressures as controls. This finding supported the notion that either component of neuropathy needs to be present before plantar pressures are elevated. Patients with diabetes mellitus demonstrated greater pressure-time integrals, implying that this variable might be the first clinical sign observable even before peripheral neuropathy could be tested.

Functional optical topography analysis using statistical parametric mapping (SPM) methodology with and without physiological confounds.

Functional optical topography (OT) measures the changes in oxygenated and deoxygenated hemoglobin (HbO(2), HHb) across multiple brain sites which occur in response to neuronal activation of the cerebral cortex. However, identification of areas of cortical activation is a complex task due to intrinsic physiological noise and systemic interference and careful statistical analysis is therefore required. A total of 10 young healthy adults were studied. The activation paradigm comprised of anagrams followed by finger tapping. 12 channels of the OT system were positioned over the frontal cortex and 12 channels over the motor cortex while the systemic physiology (mean blood pressure (MBP), heart rate (HR), scalp flux) was simultaneously monitored. Analysis was done using the functional Optical Signal Analysis (fOSA) software and Statistical Parametric Mapping (SPM), where we utilized two approaches: (i) using only HbO(2) as a regressor in the general linear model (GLM) and (ii) using all of the explanatory variables (HbO(2), MBP, HR and scalp flux) as regressors. Group analysis using SPM showed significant correlation in a large number of OT channels between HbO(2) and systemic regressors; however no differences in activation areas were seen between the two approaches.

Development of a dynamic test phantom for optical topography.

Optical topography (OT) is a near infrared spectroscopy (NIRS) technique that provides spatial maps of haemodynamic and oxygenation changes. When developing, testing and calibrating OT systems it is often necessary to use tissue simulating phantoms that are capable of providing realistic changes in attenuation properties. We present a novel dynamic tissue phantom that enables spatially and temporally varying tissue properties to be reproduced in a controlled manner. This new dynamic test phantom consists of a modified liquid crystal display (LCD) (enabling flexible and rapid changes in attenuation across different regions of the phantom) sandwiched between two layers of tissue simulating epoxy resin (providing static and homogeneous optical absorption and scattering). By activating different pixels in the liquid crystal display it is possible to produce highly localised and dynamic changes in attenuation which can be used to simulate the changes associated with the cerebral haemodynamic response to functional activation. The reproducibility of the dynamic phantom will be described with examples of its use with an OT system.

False positives in functional near-infrared topography.

Functional cranial near-infrared spectroscopy (NIRS) has been widely used to investigate the haemodynamic changes which occur in response to functional activation. The technique exploits the different absorption spectra of oxy- and deoxy-haemoglobin ([HbO2] [HHb]) in the near-infrared region to measure the changes in oxygenation and haemodynamics in the cortical tissue. The aim of this study was to use an optical topography system to produce topographic maps of the haemodynamic response of both frontal cortex (FC) and motor cortex (MC) during anagram solving while simultaneously monitoring the systemic physiology (mean blood pressure, heart rate, scalp flux). A total of 22 young healthy adults were studied. The activation paradigm comprised of 4-, 6- and 8- letter anagrams. 12 channels of the optical topography system were positioned over the FC and 12 channels over the MC. During the task 12 subjects demonstrated a significant change in at least one systemic variable (p < or = 0.05). Statistical analysis of task-related changes in [HbO2] and [HHb], based on a Student's t-test was insufficient to distinguish between cortical haemodynamic activation and systemic interference. This lead to false positive haemodynamic maps of activation. It is therefore necessary to use statistical testing that incorporates the systemic changes that occur during brain activation.

Functional optical signal analysis: a software tool for near-infrared spectroscopy data processing incorporating statistical parametric mapping.

Optical topography (OT) relies on the near infrared spectroscopy (NIRS) technique to provide noninvasively a spatial map of functional brain activity. OT has advantages over conventional fMRI in terms of its simple approach to measuring the hemodynamic response, its ability to distinguish between changes in oxy- and deoxy-hemoglobin and the range of human participants that can be readily investigated. We offer a new software tool, functional optical signal analysis (fOSA), for analyzing the spatially resolved optical signals that provides statistical inference capabilities about the distribution of brain activity in space and time and by experimental condition. It does this by mapping the signal into a standard functional neuroimaging analysis software, statistical parametric mapping (SPM), and forms, in effect, a new SPM toolbox specifically designed for NIRS in an OT configuration. The validity of the program has been tested using synthetic data, and its applicability is demonstrated with experimental data.

An integrated large- and small-group approach for conducting meetings that lead to social action.

Large meetings and small-group sessions each have advantages and deficiencies in dealing with social issues. The goals of conveying information, effectively changing attitudes, and encouraging action are often best achieved by integrating small-group sessions within the context of a large meeting. An approach involving three phases for a 2-hour meeting is described: (1) and initial plenary of all participants; (2) small-group sessions conducted by previously trained group facilitators drawn from the host organization; (3) a concluding plenary session centering around brief reports from the small groups. The application of some concepts of positive mental health, contracting, and empowerment to facilitate social action are discussed.

Electron paramagnetic resonance (EPR) studies on hydrogenase-1 (HYD1) purified from a mutant strain (AP6) of Escherichia coli enhanced in HYD1.

Hydrogenase-1 (HYD1), overexpressed by twofold, has been purified to homogeneity and to a high specific activity from a mutant strain (AP6) of Escherichia coli which lacks hydrogenase-2. Plasma emission spectroscopy indicated that 0.93 atom of nickel and 11.4 iron atoms were present in HYD1. EPR studies on the as isolated HYD1 detected a complex 3Fe-4S signal and a Ni(III) species. Reduction with hydrogen gas caused disappearance of both the 3Fe-4S cluster and initial Ni(III) signals. At the same time the EPR signature (small g = 2.19 signal) of the activated hydrogenase appeared. The detection of a 4Fe-4S cluster signal was noted. Reduction of HYD1 with sodium dithionite caused all nickel signals to disappear. The 4Fe-4S complex intensity was slightly increased. The EPR responses in the three oxidation-reduction states are consistent with other known (NiFe)-hydrogenases.

The effect of dietary selenium deficiency on acute colorectal mucosal nucleotoxicity induced by several carcinogens in the rodent.

BACKGROUND: Selenium (SE) has been inversely associated with colon cancer risk. Two potential mechanisms of this effect were examined in a rodent short-term carcinogenesis assay: whether dietary SE deficiency altered the initiation aspect of carcinogenesis in the colon, and whether SE altered carcinogen metabolism. SETTING: Animal laboratory. SUBJECTS: 52 Sprague-Dawley rats, divided into a SE diet deficient group (0.002 parts per million; ppm) and a SE sufficient (0.2 ppm) group. ENDPOINTS: Weight, serum SE concentration, and karryorhectic index (KI), which is a measure of acute carcinogen induced nuclear toxicity in the colonic mucosa. METHODS: After three weeks of acclimation to the diets, eight animals from each dietary group were injected with one of the following: dimethylhydrazine (DMH), a colon specific carcinogen, its metabolite, methylazoxymethanol (MAM), or 0.9% sodium chloride. Twenty-four hours after injection the colons were removed, blood drawn, and the stained colons assayed for nuclear aberrations. RESULTS: No weight differences were generated by the dietary variations. Low-dietary SE resulted in serum SE declining markedly in the study period to 6 ng/ml versus 33 ng/ml in the SE sufficient group. Diet alone, and variations in weight gain, did not alter the KI. Both carcinogens greatly increased the KI in both the left and right colon. A SE-deficient diet was associated with a higher KI in both carcinogen groups in the right colon, with statistical significance for both the left and right colon in the MAM injection group. CONCLUSIONS: Dietary SE deficiency is associated with increased KI of the colon in MAM treated rats. SE, therefore, has a protective effect in the initiation phase of carcinogenesis.

Identification and characterization of bacterial endophytes of rice.

We isolated seven different bacteria from rice seedlings grown from surface sterilized seeds. Three were associated with the rice seed husk and the other four were growing endophytically within the seed. Microscopic studies revealed that the endophytes were concentrated in the root stele region. Some of the bacteria exhibited strong anti-fungal activity against Rhizoctonia solani, Pythium myriotylum, Guamannomyces graminis and Heterobasidium annosum.

Cloning, sequencing, and mutational analysis of the hyb operon encoding Escherichia coli hydrogenase 2.

The genes encoding the two structural subunits of Escherichia coli hydrogenase 2 (HYD2) have been cloned and sequenced. They occur in an operon (hyb) which contains seven open reading frames. An hyb deletion mutant (strain AP3) failed to grown on dihydrogen-fumarate medium and also produced very low levels of HYD1. All seven open reading frames are required for restoration of wild-type levels of active HYD2 in AP3. The hyb operon was mapped at 65 min on the E. coli chromosome.

A role for culture in diagnosis of Helicobacter pylori-related gastric disease.

UNLABELLED: In this study, our objective was to determine the presence of Helicobacter pylori and other rapid urease-positive (RUP) organisms in gastric biopsies in 70 patients, 30 of whom had ulcers or erosions. A retrospective chart review was undertaken to correlate diagnostic tests (culture and direct urease) with results of endoscopic examination and the patient's clinical information. Eleven of 70 (15.7%) patients' biopsies were positive by both culture and direct urease for H. pylori, seven (10%) patients' biopsies were positive by culture only, and eight (11.4%) biopsies by direct urease only. Of 30 patients with ulcers (esophageal, antral, stomach, or duodenal), 15 had evidence of H. pylori infection by culture and/or direct urease test. In addition, patients with a positive direct urease test but a negative culture for H. pylori were more likely to have other rapid urease-positive organisms (RUP) isolated from their gastric biopsy cultures than patients with negative results from both tests. CONCLUSIONS: As a result of problems associated with commonly used diagnostic tests, a combination of tests performed on multiple biopsies is more sensitive and specific for the diagnosis of H. pylori infection than any single test. The common occurrence of RUP streptococcal and staphylococcal species in gastric biopsy tissue is demonstrated and proposed as a cause of false-positive direct urease tests.

Characterization of D. desulfuricans (ATCC 27774) [NiFe] hydrogenase EPR and redox properties of the native and the dihydrogen reacted states.

Redox intermediates of D. desulfuricans ATCC 27774 [NiFe] hydrogenase were generated under dihydrogen. Detailed redox titrations, coupled to EPR measurements, give access to the mid-point redox potentials of the iron-sulfur centers and of the Nickel-B signal that represents the ready form of the enzyme. The interaction between the dihydrogen molecule and the nickel centre was probed by the observation of an isotopic effect on the EPR signals detected in turnover conditions, by comparison of the H2O/H2 and D2O/D2-reacted samples.

Carboxy-terminal processing of the large subunit of [NiFe] hydrogenases.

Two electrophoretic forms of the large subunit of the soluble periplasmic [NiFe] hydrogenase from Desulfovibrio gigas have been detected by Western analysis. The faster moving form co-migrates with the large subunit from purified, active enzyme. Amino acid sequence and composition of the C-terminal tryptic peptide of the large subunit from purified hydrogenase revealed that it is 15 amino acids shorter than that predicted by the nucleotide sequence. Processing of the nascent large subunit occurs by C-terminal cleavage between His536 and Val537, residues which are highly conserved among [NiFe] hydrogenases. Mutagenesis of the analogous residues, His582 and Val583, in the E. coli hydrogenase-1 (HYD1) large subunit resulted in significant decrease in processing and HYD1 activity.

Resonance Raman studies of iron-only hydrogenases.

The nature of the iron-sulfur clusters in oxidized and reduced forms of Fe-only hydrogenases from Desulfovibrio vulgaris, Thermotoga maritima, and Clostridium pasteurianum has been investigated by resonance Raman spectroscopy. The results indicate the presence of ferredoxin-like [4Fe-4S]2+,+ and [2Fe-2S]2+,+ clusters in both T. maritima hydrogenase and C. pasteurianum hydrogenase I, but only [4Fe-4S]2+,+ clusters in D. vulgaris hydrogenase. This necessitates a reevaluation of the iron-sulfur cluster composition of C. pasteurianum hydrogenase I and indicates that the resonance Raman bands in the oxidized hydrogenase that were previously attributed to the hydrogen activating center [Macor, K. A., Czernuszewicz, R. S., Adams, M. W. W., & Spiro, T. G. (1987) J. Biol. Chem. 262, 9945-9947] arise from an indigenous [2Fe-2S]2+ cluster. No resonance Raman bands that could be uniquely attributed to the oxidized or reduced hydrogen activating center were observed. This suggests that the hydrogen activating center is a novel Fe center that is unrelated to any known type of Fe-S cluster.

Investigation of an outbreak of methicillin-resistant Staphylococcus aureus in patients with skin disease using DNA restriction patterns.

OBJECTIVE: To investigate an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) among patients using chromosomal typing of the isolates. DESIGN: Comparison of epidemiological and clinical data to endonuclease restriction fragmentation analysis (RFA) of the MRSA isolates associated with an outbreak. Total DNA from the MRSA isolates was restricted with HINDIII and HAEIII for typing. SETTING: Tertiary care academic medical center. METHODS: An epidemiological investigation of an outbreak of MRSA among patients in private rooms was evaluated by routine infection control methods. The MRSA isolates from blood cultures of 7 patients and the nares of a nurse were collected during the outbreak. MRSA isolates from 23 patients not associated with the outbreak also were collected. The total DNA of the MRSA isolates were restricted with HINDIII and HAEIII and electrophoresed on 0.6% agarose gels. RESULTS: MRSA from 4 of the 7 bacteremic patients and the nurse on the outbreak unit had the same endonuclease restriction pattern. The patients were linked in that they were compromised by severe psoriasis or skin ulcers, were on the unit during the same period, and had oatmeal baths in a common bathtub. Of 50 staff members screened, the nurse was the only person detected as colonized by the strain. The other 3 patients on the unit as well as the 23 patients in other locations not associated with the outbreak had MRSA isolates with different RFA patterns. The use of the bathtub was discontinued and further transmission of MRSA was stopped. CONCLUSIONS: A comparison of the relatedness of MRSA by RFA demonstrated the uniqueness of the epidemiologically linked isolates and the utility of the RFA technique in the performance of routine infection control investigations.

Structure-function relationships among the nickel-containing hydrogenases.

The enzymology of the heterodimeric (NiFe) and (NiFeSe) hydrogenases, the monomeric nickel-containing hydrogenases plus the multimeric F420-(NiFe) and NAD(+)-(NiFe) hydrogenases are summarized and discussed in terms of subunit localization of the redox-active nickel and non-heme iron clusters. It is proposed that nickel is ligated solely by amino acid residues of the large subunit and that the non-heme iron clusters are ligated by other cysteine-rich polypeptides encoded in the hydrogenase operons which are not necessarily homologous in either structure or function. Comparison of the hydrogenase operons or putative operons and their hydrogenase genes indicate that the arrangement, number and types of genes in these operons are not conserved among the various types of hydrogenases except for the gene encoding the large subunit. Thus, the presence of the gene for the large subunit is the sole feature common to all known nickel-containing hydrogenases and unites these hydrogenases into a large but diverse gene family. Although the different genes for the large subunits may possess only nominal general derived amino acid homology, all large subunit genes sequenced to date have the sequence R-X-C-X-X-C fully conserved in the amino terminal region of the polypeptide chain and the sequence of D-P-C-X-X-C fully conserved in the carboxyl terminal region. It is proposed that these conserved motifs of amino acids provide the ligands required for the binding of the redox-active nickel. The existing EXAFS (Extended X-ray Absorption Fine Structure) information is summarized and discussed in terms of the numbers and types of ligands to the nickel and the various redox species of nickel defined by EPR spectroscopy. New information concerning the ligands to nickel is presented based on site-directed mutagenesis of the gene encoding the large subunit of the (NiFe) hydrogenase-1 of Escherichia coli. Based on considerations of the biochemical, molecular and biophysical information, ligand environments of the nickel in different redox states of the (NiFe) hydrogenase are proposed.

Minerals in hair, serum, and urine of healthy and anemic black children.

Hair mineral analysis can be used as a reliable screening test for heavy metals, but it is not an established method for defining nutritional and disease states. Wide variation in test results is a major problem in utilizing the technique for clinical purposes. Better reference values are needed, especially for children, as well as information about how hair mineral values correlate with body fluid values. A total of 48 black children were studied. Of these, 20 were normal children, ages 1 to 17; 12 were normal infants, ages 5 weeks to 12 months; 3 were children with iron overload; 7 had iron deficiency anemia; and 6 had thalassemia trait. There were in all 17 boys and 31 girls. The distribution of 15 minerals in hair, serum, and urine samples was determined by energy dispersive X-ray fluorescence. Mineral concentrations from the normal children were compared with concentrations obtained from the children with iron overload, iron deficiency anemia, and thalassemia trait. Statistical analysis revealed no significant differences among any of the groups. Mineral concentrations from the normal infants and children may be useful as reference values. The analysis of hair iron as a valid screening test for body iron status in children is not supported by our data.

Novel method of purification of human leukocytic elastase using adsorption on a high-performance liquid chromatography gel permeation column.

Neutrophil elastases are serine proteinases released during acute and chronic inflammatory states. We have developed a novel isolation method for neutrophil elastase, involving conventional gel chromatography followed by adsorption of protein at low ionic strength on a high-performance liquid chromatography gel permeation column. The bound elastase is then eluted by application of higher ionic strength. This adsorption step at low ionic strength, a step to be avoided in most purification methods, was used to advantage here to allow isolation of homogeneous material. This purification procedure should be useful for quick, simple bulk preparation of the enzyme.