Efficacy of feedback from quarterly laboratory comparison in maintaining quality of a hospital capillary blood glucose monitoring program

OBJECTIVE

A 1-year randomized prospective study was conducted to investigate the efficacy of feedback from split-sample testing as part of a capillary blood glucose quality assurance program.

RESEARCH DESIGN AND METHODS

A total of 124 nurses were randomized to either group A (quarterly comparisons with feedback) or group B (no feedback). The measure of nurse accuracy against the laboratory at 0, 6, and 12 months was determined by an additional five to seven split-sample tests without giving feedback to either group. Mean accuracy was determined in terms of percent absolute deviation from the laboratory result and a clinical consensus limit of +/- 20% deviation from the laboratory.

RESULTS

By 12 months, there was a significant effect of feedback on nurse agreement with the laboratory method (P = 0.022 when agreement was scored as the mean percent absolute difference and P = 0.002 when agreement was scored in terms of the +/- 20% clinical consensus limit). Nurses in the group who had received no quarterly feedback from split-sample testing produced a 3.5% greater mean percent absolute deviation from the laboratory method and 12% fewer comparisons within the acceptable +/- 20% range.

CONCLUSIONS

Feedback received from split-sample testing has a significant effect in maintaining accuracy in capillary blood glucose monitoring.

Context-dependent interactions and visual processing in V1

We examined the influence of stimulus context on the response of cells in primate V1 utilising both concentric and spatially discrete stimuli. The majority of cells (63/71) showed marked patch suppression, including non-oriented cells. This suppression was reduced or lost if there was an orientation discontinuity in the stimulus overlying the receptive field. Cross-oriented stimuli could exert strong facilitatory effects so that a cell's response to an optimally oriented stimulus over its receptive field was increased by the presence of an adjacent cross-oriented stimulus. This increase appeared to involve both disinhibition as well as a direct facilitation. The strength of the cross-orientation effects was such that for some cells it seemed appropriate to define a cross-oriented stimulus configuration as the 'optimal' stimulus. Effects following from orientation context could be strongly influenced by stimulus direction. Subcortical as well as cortical interactions may contribute to these observations. It is suggested that the properties of the network as a whole define the responses of individual cells and that the representation of discontinuities is an important component of network function in V1.

Visual cortical mechanisms detecting focal orientation discontinuities

Neurons in the primary visual cortex (V1) respond in well defined ways to stimuli within their classical receptive field, but these responses can be modified by stimuli overlying the surrounding area. For example patch-suppressed cells respond to gratings of a specific orientation within their classical receptive field, but the response diminishes if the grating is expanded to cover the surrounding area. We report here more complex effects in many such cells. When stimulated at their optimal orientation, introducing a surrounding field at a significantly different (for example, orthogonal) orientation enhanced their output by both a disinhibitory mechanism and an active facilitatory mechanism producing 'supra-optimal' responses. Importantly, some cells responded well if the orientations of centre and surround stimuli were swapped. The output reflected the discontinuity because neither stimulus component alone was effective. Under these stimulus conditions simultaneously recorded cells with orthogonally oriented receptive fields showed correlated firing consistent with neuronal binding to the configuration. We propose a mechanism integrating orientation-dependent information over adjacent areas of visual space to represent focal orientation discontinuities such as junctions or corners.

Classification of prosthetic heart valve sounds: a parametric approach

People with heart problems have had their lives extended considerably with the development of the prosthetic heart valve. Great strides have been made in the development of the valves through the use of improved materials as well as efficient mechanical designs. However, since the valves operate continuously over a long period, structural failures can occur--even though they are relatively uncommon. Here the development of techniques to classify the valve either as having intact struts or as having a separated strut, commonly called single leg separation, is discussed. In this paper the signal processing techniques employed to extract the required signals/parameters are briefly reviewed and then it is shown how they can be used to simulate a synthetic heart valve database for eventual Monte Carlo testing. Next, the optimal classifier is developed under assumed conditions and its performance is compared to that of an adaptive-type classifier implemented with a probabilistic neural network. Finally, the adaptive classifier is applied to a data set and its performance is analyzed. Based on synthetic data it is shown that excellent performance of the classifiers can be achieved implying a potentially robust solution to this classification problem.

Processing of prosthetic heart valve sounds for single leg separation classification

People with serious heart conditions have had their expected life span extended considerably with the development of the prosthetic heart valve especially with the great strides made in valve design. Even though the designs are extremely reliable, the valves are mechanical and operating continuously over a long period; therefore structural failures can occur due to fatigue. In this paper acoustical signal processing techniques developed to process noisy heart valve sounds measured by a sensitive, surface contact microphone are discussed. Measuring heart sounds noninvasively in a noisy environment puts more demands on the signal processing to extract the desired signals from the noise. Heart valve sounds are short-duration (10-20 ms) transients and therefore nonstationary, requiring more sophisticated processing algorithms to achieve the desired signal-to-noise ratios. In this paper the preclassification signal processing is concentrated on exclusively. That is, the signal processing operations performed on the heart valve sounds prior to classification are discussed--a subject that will be developed in a future paper. Efforts are concentrated on the sounds corresponding to the heart valve opening cycle. Valve opening and closing acoustics present additional information about the outlet strut condition--the structural component implicated in valve failure. The importance of the opening sound for single leg separation detection/classification is based on the fact that as the valve opens, the disk passively hits the outlet strut. The opening sounds thus yield direct information about outlet strut condition with minimal amount of disturbance caused by the energy radiated from the disk. Hence the opening sound is a very desirable acoustic signal to extract. Unfortunately, the opening sounds have much lower signal levels relative to the closing sounds and therefore noise plays a more significant role than during the closing event. Because of this it is necessary to screen the sounds for outliers in order to insure a high sensitivity of classification. Because of the sharp resonances appearing in the corresponding spectrum, a parametric processing approach is developed based on an autoregressive model which was selected to characterize the sounds emitted by the Bjork-Shiley convexo-concave (BSCC) valve during opening cycle. First the basic signals and the extraction process used to create an ensemble of heart valve sounds are briefly discussed. Next, a beat monitor capable of rejecting beats that fail to meet an acceptance criteria based on their spectral content is developed.(ABSTRACT TRUNCATED AT 400 WORDS)

Prenatal stress attenuates ulceration in the activity stress paradigm

In the present study, 28 pregnant rats were subjected to either light-restraint stress or no manipulation for days 14-21 of the gestational period. At approx. 50 days of age, both male (n = 16) and female (n = 16) prenatally stressed (PS) and control offspring were subjected to the activity stress (AS) paradigm. During this subsequent stress experience, PS rats developed less ulceration than control rats. PS rats also displayed about half the activity of the control animals during the habituation phase of the AS paradigm, prior to the induction of stress. Given this decrease in baseline activity in PS animals, implications of using activity as a measure of emotionality in PS animals are discussed. Several sex differences were also observed; females differed from males in that they 1) exhibited higher activity levels in both the habituation and experimental phases of the AS procedure, 2) developed heavier relative adrenal weights, and 3) reached criteria for sacrifice in fewer days.

Directional asymmetries in the length-response profiles of cells in the feline dorsal lateral geniculate nucleus

1. The visual cortex provides a major synaptic input to the dorsal lateral geniculate nucleus (dLGN). Cortical layer VI cells giving rise to this projection are strongly influenced by stimulus orientation, length and direction of motion. In the dLGN, a significant component of the strong length tuning exhibited by most cells follows from the corticofugal influence. We have now checked whether there are directional biases in geniculate cell responses, and whether such biases are influenced by stimulus length. 2. The responses of A-laminae dLGN cells were assessed by single-unit extracellular recording. Length preference was examined by plotting multihistogram length-tuning curves to moving bars of light of various length. 3. Over half of the cells tested (100/183) exhibited directional bias and in many cases, this bias was highly dependent on bar length, resulting in radically different length response profiles for the two directions of motion. These asymmetries are similar to those documented for cortical hypercomplex cells, but do not equate to any known facet of the centre-surround organization of dLGN cell receptive fields. 4. We suspected the directional biases followed from the influence of the corticofugal projection. To test this, we recorded from preparations where areas 17 and 18 of the visual cortex had been removed. Surprisingly, a similar proportion of cells exhibited directional biases after removal of the corticofugal input, suggesting that the biases are generated subcortically. 5. The widespread presence of systematic biases in the response profiles of dLGN cells further underlines the possibility that geniculate mechanisms may make a far greater contribution to visual processing than hitherto suspected.

The length-response properties of cells in the feline perigeniculate nucleus

Perigeniculate cells receive visual input from the dorsal lateral geniculate nucleus (dLGN) and from the visual cortex. In contrast to the extensive literature documenting dLGN and cortical cell responses, comparatively little quantitative data exists for perigeniculate nucleus cells, and very little is known about the role of the corticofugal input to the perigeniculate nucleus. We have previously shown that dLGN relay cells have sharply length-tuned receptive fields and that a significant component of this is dependent on the corticofugal system. In this report, we have explored the length-response properties of perigeniculate nucleus cells in the presence and absence of corticofugal feedback. The response profiles of most perigeniculate nucleus cells contrasted markedly with the sharply length-tuned fields of dLGN cells, but exhibited a notable resemblance to those exhibited by VI cells with short summation lengths, which have recently been shown to constitute a considerable proportion of the layer VI cell population. This might suggest that the responses of perigeniculate nucleus cells to long bars derive from their cortical input. However, our data failed to reveal a discernible change in their profiles after removal of the corticofugal drive. This surprising observation implies that their length-tuning profiles follow from subcortical circuitry. The ways in which this might occur are discussed.

Feature-linked synchronization of thalamic relay cell firing induced by feedback from the visual cortex

The function of the massive feedback projection from visual cortex to its thalamic relay nucleus has so far eluded any clear overview. This feedback exerts a range of effects, including an increase in the inhibition elicited by moving contours, but the functional logic of the direct connections to the thalamic cells that relay the retinal input to the cortex remains largely unknown. In contrast to its thalamic nucleus, the visual cortex is characterized by cells that are strongly sensitive to the orientation of moving contours. Here we report that when driven by moving oriented visual stimuli the cortical feedback induces correlated firing in relay cells. This cortically induced correlation of relay cell activity produces coherent firing in those groups of relay cells with receptive field alignments appropriate to signalling the particular orientation of the moving contour to the cortex. Synchronization of relay cell firing means that they will elicit temporally overlapping excitatory postsynaptic potentials in their cortical target cells, thus increasing the chance that the cortical cells will fire. Effectively this increases the gain of the input for feature-linked events detected by the cortex. We propose that this feedback loop serves to lock or focus the appropriate circuitry onto the stimulus feature.

Fibreoptic intubation. Influence of tracheal tube tip design

A randomised study was carried out in 60 patients to assess the influence of tracheal tube tip design on the ease of railroading a tracheal tube during fibreoptic intubation. A new design of tracheal tube with a tapered tip, without a bevel, was compared with a tracheal tube of standard design. The new design was found to be greatly superior in both oro- and nasotracheal fibreoptic intubation, when compared with the traditional tracheal tube (p < 0.001). The shape of the tip of a tracheal tube is an important determinant of the ease of railroading the tube over an inserted fibrescope.

The accumulation of pentamidine and the toxic effects of the drug, its selected analogues and metabolites on isolated alveolar cells

Radiolabelled [3H]pentamidine is accumulated into 48-h and 7-day cultures of alveolar epithelial type 2 cells and alveolar macrophages in a linear, time and dose-dependent manner, with the rate of uptake being 15.3, 13.4 and 17.9 pmol/micrograms protein per 30 min, respectively. Uptake was not affected by metabolic inhibitors. The differential toxicity of the parent drug pentamidine, five analogues and six metabolites was assessed on freshly isolated and type 2 cells maintained in culture over 24 h. Toxicity, determined by the attachment ability of alkaline phosphatase positive cells containing lamellar bodies was greater in freshly isolated cells. Overall, three/four of the analogues proved less damaging to type 2 cells than the pentamidine with one derivative [1,3-bis(4-amidino-2-methoxy)propane], a compound particularly efficacious against pneumocystis in rats, showing minimal toxicity. Five metabolites (chain hydroxylated derivatives) were less toxic than the parent drug. However, one metabolite (N,N-dihydroxy derivative) was much more toxic than pentamidine to both type 2 cells and alveolar macrophages. It is concluded that as the type 2 cell can accumulate the drug, it represents a target cell which is particularly sensitive to pentamidine and/or some of its metabolites.

Immune response and host resistance of humans to dermatophyte infection

Clearing of dermatophyte infection depends on a cell-mediated immune response. Antibodies to fungi, although present in infected persons, are ineffective at ridding the skin of fungi. Experiments in which human volunteers were deliberately infected with dermatophytes identified two major groups on the basis of cellular immune responsiveness: (1) those who mount decisive delayed-type hypersensitivity that results in clearing of the infection, and (2) those who have absent or defective cellular immunity that prevents them from mounting an effective response to dermatophytes and thus predisposes them to chronic or recurrent dermatophyte infection. The courses of experimental infection in these two groups were compared with skin test results. The presence of an acute inflammatory infection was correlated with delayed-type (T-cell-mediated) hypersensitivity to a trichophytin skin test and the ability of persons affected in this manner to achieve mycologic cure. In contrast, chronic infection was associated with high immediate (anti-Trichophyton-IgE-mediated) hypersensitivity and low or waning delayed-type (T-cell-mediated) hypersensitivity to trichophytin. Despite this immune deficiency, these persons had a normal response to other infectious agents and skin test antigens. This type of selective and perhaps induced immune deficit may be relatively common, because persons chronically infected with a dermatophyte constitute 10% to 20% of the general population.

Acid phosphatase activity in the larval salivary glands of developing Drosophila melanogaster

Both the biochemical profile and the optical and fine structural localization of acid phosphatase activity in the larval salivary glands of developing Drosophila melanogaster is described. Biochemically, acid phosphatase shows peak activity in the glands of feeding larvae, followed by a marked decline. Directly preceding the onset of cell histolysis however, enzyme activity increases 1.5 fold and is maintained at this level. Histochemically, acid phosphatase activity initially appears as discrete point or lysosomal sources. As development proceeds, an intense and diffuse form of enzyme is seen, accompanying an extremely vacuolated cytoplasm. Ultrastructurally, the enzyme is located in lysosomes, Golgi elements, multivesicular bodies and both within, and on the extracisternal surface of the rough endoplasmic reticulum. This extracisternal or cytosolic form appears directly preceding cell lysis and eventually shows a comprehensive cellular distribution. Large numbers of acid phosphatase positive haemocytes are attached to the basal glandular surface at all developmental stages. In morphologically intact gland cells, discrete extracisternal enzyme activity appears associated with local areas of degradation.

Dose-dependent distribution of 3H-pentamidine following intra-tracheal administration to rats

1. The acute toxicity to the lung, and disposition, of pentamidine isethionate as a function of a pulmonary-delivered dose was investigated in the rat. 2. Acute toxicity 24 h following intra-tracheal instillation of pentamidine was determined by analysis of acellular surface protein concentration and differential cell counting of bronchoalveolar lavage fluid. These two parameters indicated that pentamidine doses > 10 mg/kg lead to increasingly severe oedematous and inflammatory responses within the lung. 3. Following intra-tracheal administration of sub-toxic doses of 3H-pentamidine (0.2-10 mg/kg), the extent of activity in liver, kidney, gut and lavage fluid at 24 h correlated significantly with dose, whereas the level of activity in lung was saturated at doses > 0.8 mg/kg. 4. Values of << 1 for liver:lung and kidney:lung ratios of 3H-activity at low pentamidine doses demonstrated the high affinity of the lung for the compound. These ratios substantially increased with pentamidine dose, reflecting distribution of the drug to liver and kidney. Association of radioactivity with these organs was rapid (< 30 min), and indicated that pentamidine is effectively absorbed from the respiratory tract following intra-tracheal instillation.

Lipid composition of subcellular membranes from larvae and prepupae of Drosophila melanogaster

Subcellular membranes were analyzed for their lipid composition and protein content at two developmental points representing the third instar wandering larvae and prepupal stages of Drosophila. At both stages, phosphatidylethanolamine (PE) and phosphatidylcholine (PC) were the major constituents with phosphatidylinositol (PI), phosphatidylserine (PS), diphosphatidylglycerol (DPG) and phosphatidic acid (PA) being relatively minor components. In total homogenates and in the nuclear-enriched fraction there was no significant difference in the phospholipid composition of the wandering larvae and prepupae. In mitochondria only a significant increase in the minor component PS was observed in the prepupae. In lysosomal membranes on the other hand, the relative abundance of the major components PE and PC increased in the prepupae although the molar ratios of the two lipids remained almost constant. The fatty acid composition of the phospholipids remained virtually unchanged in all of the fractions examined, including the lysosomes, and there was no evidence of lipid peroxidation. With regard to cellular degeneration and the involvement of lysosomes, we conclude that mechanisms other than gross modification of the lipid and/or lipid/protein ratio of their membranes are involved in the liberation of the acid phosphatase contents.

The action of the putative neurotransmitters N-acetylaspartylglutamate and L-homocysteate in cat dorsal lateral geniculate nucleus

1. We have examined the actions and pharmacology of two putative optic nerve transmitters, N-acetylaspartylglutamate (NAAG) and L-homocysteic acid (L-HCA), in the feline dorsal lateral geniculate nucleus (dLGN). We compared the responses obtained to iontophoretic application of these substances with those elicited by visual stimulation and application of specific N-methyl-D-aspartate (NMDA) and non-NMDA receptor agonists. The relative effects of the selective NMDA antagonist 3-[(+/-)-2-carboxypiperazin-4-yl]-propyl-1-phosphonic acid (CPP) and the selective non-NMDA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) were tested on these responses. 2. There was a pronounced contrast between the influence of iontophoretically applied NAAG and L-HCA on dLGN cells. Iontophoretic application of NAAG [ejection current range 75–200 nA (mean 125 nA)] evoked either no effect (17/37), or very weak and sluggish excitatory (16/37) or inhibitory (4/37) effects. Conversely, L-HCA application [current range 25–136 nA (mean 67 nA)] elicited brisk and powerful excitatory responses (32/32) that were comparable with those produced by visual stimulation and iontophoresis of NMDA, kainate, and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). 3. Responses to L-HCA were selectively antagonized by application of the NMDA receptor antagonist CPP but were generally much less affected by the non-NMDA receptor antagonist CNQX. The weak and inconsistent responses to NAAG were not compatible with an evaluation of antagonist effects. 4. CPP application at dose levels selective for NMDA with respect to kainate and AMPA did not exert equal effects on L-HCA and NMDA. Whereas the mean responses to L-HCA were reduced to 32% of control for Y cells and 21% for X cells, those to NMDA were 11 and 11%, respectively. However, the level of reduction of the visual response for X and Y cells was very similar to that of L-HCA, visual responses being reduced to 35 and 22% of control for Y and X cells. 5. CNQX application reduced the visual response level of Y cells to 64% of control and that of X cells to 65%. The mean level for the L-HCA response of Y cells was 106% of control; the mean for X cells, 79%, was substantially below control. The responses to kainate and AMPA were reduced to a much greater extent. 6. The data suggest that it is unlikely that NAAG is the optic nerve transmitter.(ABSTRACT TRUNCATED AT 400 WORDS)

The accumulation of pentamidine into rat lung slices and its interaction with putrescine

The aromatic diamidine, pentamidine, accumulated into rat lung slices by an uptake system that obeyed saturation kinetics, with an average Km value of 554 microM and a Vmax value of 4077 nmol/g lung wet wt/30 min, respectively. This system was not inhibited by metabolic inhibitors but was greatly diminished by lowering the temperature from 37 degrees to 4 degrees. Both compounds, pentamidine and putrescine, inhibited the uptake of the other and the inhibition of pentamidine accumulation by putrescine was demonstrated to be non-competitive. Uptake of putrescine was inhibited by increasing concentrations of pentamidine. As putrescine accumulates in epithelial type 1 and type 2 cells and in Clara cells, it is likely that pentamidine is also accumulated in these cell types but does not utilize the pulmonary uptake system for polyamine transport. Within the time period studied, toxic effects of the drug were not observed.

The length-response properties of cells in the feline dorsal lateral geniculate nucleus

1. In this report we have systematically examined the length-response properties of a large population of cells recorded in the cat dorsal lateral geniculate nucleus (dLGN). The responses of A laminae dLGN cells were assessed by the use of conventional single-unit extracellular recording techniques. The length preference of these cells was examined by plotting multihistogram length tuning curves to moving bars of light. Bar length was randomized in an interleaved fashion under computer control. The other stimulus parameters were standardized within the limits of those routinely used to assess the length preference of cortical cells. 2. The majority of cells (186/198), whose length-response properties are considered in detail in this report, exhibited strong centre-surround antagonism and a mean degree of length tuning equivalent to, or exceeding, that seen in most cortical hypercomplex cells (71 +/- 1.18%, S.E.M., n = 186). 3. The values for X cells (74 +/- 1.41%, S.E.M., n = 100) and Y cells (67 +/- 2.13%, S.E.M., n = 74) were very similar, as were those of the on-centre (71 +/- 1.51%, S.E.M., n = 123) and off-centre (71 +/- 1.85%, S.E.M., n = 63) subgroups. 4. A distinct subgroup of the Y cell population was identified. These comprised the remaining twelve out of the 198 cells examined and their response properties were sufficiently distinct to merit classification as a discrete subpopulation of cells which we have termed nlY cells. They were characterized by very poor levels of both centre-surround antagonism and length tuning, and were most frequently encountered close to laminar borders. Their response properties have been described in detail elsewhere. 5. We quantitatively compared the degree of length tuning seen with moving bars to the strength of centre-surround antagonism assessed with flashing spots. The degree of length tuning did not necessarily follow the level of centre-surround antagonism. 6. Examination of the effects of unilaterally extending bar length to one or other side of the receptive field did not reveal the type of asymmetry frequently seen in cortical hypercomplex cells. 7. The high degree of length tuning seen in this study underlines the potential importance of geniculate response properties to the generation of the length-response properties of cortical hypercomplex cells. The findings are discussed in relation to the synaptic mechanisms contributing to the generation of length tuning at subcortical and cortical levels.

The laryngeal mask airway in paediatric anaesthesia

Forty-eight children, aged between 2 and 10 years, admitted as day cases for otological surgery were allocated at random into two groups. The first group was anaesthetised using a standard facemask, and the second with a laryngeal mask airway. The laryngeal airway produced a satisfactory airway in all children, and was inserted on the first attempt in 67% of patients. Hypoxia was significantly less frequent in the laryngeal airway group (p less than 0.05), and there were significantly fewer interruptions to surgery than in the facemask group (p less than 0.001). Patient safety, operating and anaesthetic conditions were all considered superior in the laryngeal airway group.

Problems of resistant dermatophytes

Recalcitrant fungal infections are defined as infections that are difficult or impossible to eradicate despite seemingly adequate treatment with appropriate oral or parenteral antibiotics. Relative or absolute microbial resistance is only one of the many causes of recalcitrance. Others include failure of the patient to comply with the prescribed treatment regimen, drug degradation in the liver, drug-drug interactions, reabsorption or washout of the drug from the stratum corneum, and failure of the drug to reach the stratum corneum. Excretion in the eccrine sweat is the principal pathway by which griseofulvin and ketoconazole, the two currently available oral antifungal agents, are delivered to the stratum corneum. Measures that promote delivery of these drugs to this site by enhancing sweating and minimizing drug run-off and absorption onto clothing may aid in optimizing the therapeutic response to these agents.

A specific subgroup of non-length tuned relay cells in the feline dorsal lateral geniculate nucleus

Length tuning was first described for the "hypercomplex cell category" in the visual cortex. However it has subsequently become apparent that cells in the dorsal lateral geniculate nucleus (dLGN) also exhibit a high degree of length tuning and that for the majority of the population this matches or exceeds that associated with cortical hypercomplex cells (Cleland et al. 1983; Jones and Sillito 1987). In this paper we describe a distinct subpopulation of dLGN Y cells that lack length tuning. These cells were also characterised by poor centre-surround antagonism, and tended to be located close to laminar borders. They appeared to constitute 25% of the Y cell population. Following recent evidence showing relay cells to be powerfully excited by acetylcholine, and inhibitory interneurones to be inhibited, we have examined the responses of these non-length tuned cells to iontophoretic application of acetylcholine. Their brisk excitatory responses suggest that these cells are in fact relay cells. Their presence raises the possibility of a discrete non-length tuned component to the geniculate input to the cortex, and has potentially important implications for the way in which synaptic processes contributing to the length tuning profiles of visual cortical cells are modelled.

An animal model for altering the irritability threshold of normal skin

Theory behind conditioned hyperirritability (autoeczematization) predicts the lowering of the irritation threshold in the presence of a pre-existing dermatitis. We have attempted to develop an animal model that parallels the syndrome seen in man. Groups of 10 guinea pigs were shaved and depilated; irritation thresholds to benzalkonium chloride and trichloroacetic acid were determined using 1 cm diameter open patches. Reactions were scored 24 h later on the basis of erythema and induration. Animals having as little as 1.56 cm2 of skin acutely inflamed with a known irritant had lowered irritation thresholds to the same irritant on normal skin at remote sites (p less than 0.01). Mild irritation of a much larger surface area produced the same effect (p less than 0.01). More extensive, severe dermatitis did not lower the irritation threshold further. Acute dermatitis induced by a contact allergen (DNCB) lowered the irritation threshold of normal skin to the same level as that obtained with irritants (p less than 0.01). Induction of chronic cutaneous ulcers 3-4 cm in diameter lowered the irritation threshold of normal skin to the same point defined by the acute studies (p less than 0.01). These results indicate that an acute irritant or contact dermatitis, as well as chronic skin ulceration, may alter the reactivity of unaffected normal skin to exhibit a heightened response to irritation. This model appears to differ from that seen in humans, in that a more extensive or chronic dermatitis did not further heighten the susceptibility to irritation.

Chronic dermatophyte infection: evaluation of the Ig class-specific antibody response reactive with polysaccharide and peptide antigens derived from Trichophyton mentagrophytes

An enzyme-linked immunosorbent assay was used to detect serum antibodies within Ig classes IgG, IgM, IgA, and IgE against two partially purified Trichophyton mentagrophytes-derived antigens: polysaccharide (SAC) and peptide (PEP). Sera from 27 chronically infected adults, 16 normal noninfected adults, and 17 noninfected children were evaluated. All sera were reactive, indicating that circulating antibody reactive to PEP and SAC is a feature common to most people, regardless of age and the presence of active infection. The reactivity to SAC was much greater than to PEP. Inhibition assays revealed that components of PEP are found in SAC. Chronically infected adults showed slightly elevated IgG and IgA reactivity to both SAC and PEP compared with noninfected normal adults. This elevated reactivity correlated with the extent (% surface affected) of cutaneous infection. IgE antibody reactivity was detected only against SAC and was somewhat elevated in chronically infected adults. There was no association between antibody reactivity and immunoglobulin level or between the individual subject's level of antibody reactivity to PEP and SAC.

Orally administered ketoconazole: route of delivery to the human stratum corneum

Delivery of ketoconazole to human stratum corneum was studied. Thirteen healthy volunteers, three patients with chronic fungal disease and one patient with palmar-plantar hyperhidrosis were given 400 mg of ketoconazole daily for various lengths of time. The ketoconazole content of palmar stratum corneum, eccrine sweat, sebum, and serum was measured by high-pressure liquid chromatography (sensitivity, 0.005 to 0.010 microgram/ml). Palmar stratum corneum obtained after 7 and 14 days of daily administration contained up to 14 micrograms of ketoconazole per g. Ketoconazole was not found in sebum after 7 or 14 days of daily ingestion of the antimycotic agent. Sebum from three patients with chronic fungal infection treated for greater than 9 months contained ketoconazole (means, 4.7 micrograms/g). Thermogenic whole body eccrine sweat contained a mean of 0.059 microgram/ml on day 7 and 0.084 microgram/ml on day 14 of daily administration. Ketoconazole appeared in thermogenic whole body eccrine sweat and palmar hyperhidrotic sweat within 1 h after a single oral dose. Partition studies of ketoconazole containing eccrine sweat demonstrated a 10-fold greater concentration in the sediment phase (desquamated keratinocytes) compared with the clear supernatant phase. In vitro studies with [3H]ketoconazole-supplemented supernatant sweat revealed preferential binding to stratum corneum, hair, and nails and its partitioning to lipid-rich sebum. We conclude that eccrine sweat rapidly transports ketoconazole across the blood-skin barrier, where it may bind or partition to keratinocytes and surface lipids.

Restoration of Trichophyton mentagrophytes growth in medium depleted of metals by chelation: importance of iron

The present study examined the requirement of Trichophyton mentagrophytes ATCC-18748 for iron. Nutrient broth depleted of iron by the chelating cation exchange resin Chelex-100 did not support the growth of T. mentagrophytes beyond germ tube formation. The soluble chelate of iron, ferric ammonium citrate, restored the capacity of the chelated medium to support fungal growth in proportion to the amount of iron added. Ferric chloride, which rapidly becomes insoluble at neutral pH, was not effective in the medium. The soluble salts of cobalt, chromium, copper, manganese, nickel, and zinc individually did not replace the requirement for iron. A method for defining the iron requirement based upon utilization of iron from ferric ammonium citrate is described. These data indicate that the growth of T. mentagrophytes ATCC-18748 is iron-dependent, which is consistent with the hypothesis that serum transferrin inhibits dermatophyte growth by the mechanism of iron deprivation.

A mechanism of susceptibility to mucormycosis in diabetic ketoacidosis: transferrin and iron availability

The defect in host defense that makes the diabetic ketoacidotic (DKA) patient susceptible to mucormycosis has not been identified. Sera from 10 DKA patients and three normal volunteers were tested for their capacity to support the in vitro growth of a common etiologic agent of mucormycosis, Rhizopus oryzae. After equilibration with room air none of the normal or DKA sera, each of which was now extremely alkaline, supported growth of R. oryzae. When the sera were placed in a CO2 atmosphere that permitted simulation of the in vivo clinical pH (normal 7.40 and DKA 7.3-6.6), four of seven DKA sera supported profuse fungal growth. No growth occurred in normal serum. The three DKA sera that did not support fungal growth at pH less than or equal to 7.3 contained less iron (x = 13 micrograms/dl) than the four sera that supported profuse fungal growth (x = 69 micrograms/dl). Increasing the iron content of iron-poor DKA serum that did not support R. oryzae growth allowed profuse growth at acidotic conditions but not at pH greater than or equal to 7.4. Simulated acidotic conditions (pH 7.3-6.6) also decreased the iron-binding capacity of normal serum stepwise from 266 micrograms/dl to 0. Our data indicate that acidosis temporarily disrupts the capacity of transferrin to bind iron and suggest that this alteration abolishes an important host defense mechanism that permits growth of R. oryzae.

Pyrophosphate arthropathy: a clinical and radiological study of 105 cases

105 consecutive patients who presented to a rheumatologist because of joint disease and who also had evidence of deposition of calcium pyrophosphate dihydrate (CPD) were studied clinically and radiologically. There were 76 women (mean age 73) and 29 men (mean age 62). Of only 18 patients below the age of 60 at presentation 12 were men. The majority of the younger male group suffered from acute attacks of synovitis, and had no clinical or radiological evidence of joint damage. In contrast the older female group had widespread destructive changes. Associated joint disease included generalised osteoarthritis (45), rheumatoid arthritis (8), joint hypermobility (13), previous knee surgery (8), and gout 92). Sixteen patients had received long-term steroid therapy. Severe destructive joint changes were seen in 16 patients. The radiological features in those with rheumatoid arthritis by ARA criteria were atypical. The relationship between CPD deposition and arthritis is discussed in the light of these findings.

Serum concanavalin-A binding in rheumatoid arthritis

A nephelometric assay of concanavalin-A binding of serum acute phase proteins (con-A binding) has been used in cross-sectional and sequential studies of disease activity in rheumatoid arthritis (RA). Con-A binding correlated well with blood viscosity, C-reactive protein, and other individual acute phase reactants in patients with active RA. Twenty-four patients were treated for 6 months with D-penicillamine and assessed clinically and seriologically. Clinical improvement was accompanied by significant falls in both C-reactive protein and con-A binding, although the serological changes did not always occur in parallel in individual patients. The advantages of this simple, cheap assay of acute phase proteins are discussed.

Oral ketoconazole. An effective and safe treatment for dermatophytosis

This study demonstrates the efficacy and safety of ketoconazole, a broad-spectrum oral antifungal agent administered to 20 patients with severe, extensive, and recalcitrant Trichophyton rubrum infection. The average patient has had continuous infection for 20 years. Sixteen patients had glabrous skin infection that encompassed an average of 40% of their skin surface. The remaining four patients had palmar-plantar infection. Ketoconazole was administered for 27 to 70 days in a daily oral dose of 200 or 400 mg. Initial clinical and mycological response occurred within five to seven days, and the glabrous and/or palmar-plantar skin changes improved at least 90% in all patients. In 13 of these patients, the infection cleared completely. The only side effects experienced--pruritus in four patients and photophobia in two patients--did not necessitate interruption of therapy. Overall, ketoconazole was found to be an effective and safe therapy for dermatophytosis. Follow-up examinations of our cases five months later showed recrudescence in 75% of them, which was not unexpected with these severe infections.

Griseofulvin-resistant dermatophytosis correlates with in vitro resistance

The unsuccessful treatment of dermatophytosis with griseofulvin is common. The mechanism is not known but may involve infection with a griseofulvin-resistant dermatophyte. The mean minimal inhibitory concentration (MIC) value of griseofulvin for Trichophyton rubrum isolates obtained from griseofulvin unresponsive patients was substantially larger than the mean MIC value for responsive control isolates. This difference indicates that therapeutic failure does correlate with the relative in vitro resistance. An MIC of 3.0 microgram/mL or greater was determined to indicate relative griseofulvin resistance. We conclude that the MIC determination for griseofulvin can be used to determine the appropriateness of griseofulvin therapy.

Intra-articular steroids in osteoarthritis

Intra-articular steroid therapy for osteoarthritis of the knee has been reassessed by two placebo-controlled trials of 20 mg of triamcinalone hexacetonide in 48 joints. Steroid injections caused a significantly greater reduction in pain and tenderness than placebo, and were preferred by patients. However, the benefits were small and transient. Maximum pain reduction occurred one week after injection, and was accompanied by a fall in the thermographic index suggesting an anti-inflammatory mode of action. Synovial fluid was unafffected by injections, and there was no correlation between synovial fluid cell counts or the radiological grading, and the degree of pain reduction.

The effect of human lymphokine on the growth of Trichophyton mentagrophytes

Lymphokine was tested for fungal growth inhibitory activity against the filamentous fungus Trichophyton mentagrophytes. Human peripheral blood lymphocytes from a donor exhibiting delayed type cutaneous hypersensitivity to a trichophytin skin test were cultured with trichophytin and PHA-P. Culture supernatants were assayed for lymphokine activity using the lymphotoxin sensitive mouse L-929 alpha fibroblast. Lymphocyte activation to PHA-P and trichophytin was confirmed by monitoring 3H-thymidine incorporation. Supernatants from 2-day PHA-P and 6-day trichophytin activated cultures were found to contain potent lymphokine activity. This activity was not diminished by the addition of ferric iron sufficient to saturate the contained transferrin. Supernatants from unstimulated control cultures contained no lymphokine activity. Undiluted lymphokine containing supernatants and nonlymphokine containing control supernatants were evaluated for fungal growth inhibitory activity using a sensitive radiometric growth assay. Iron supplemented supernatants retaining potent lymphokine activity did not inhibit fungal growth. Non-iron supplemented supernatants and fresh medium containing serum inhibited fungal growth. Our data suggest that lymphokine active against mammalian cells is not directly antagonistic to the growth of the filamentous fungus T. mentagrophytes but does not exclude the possibility that activated lymphocytes release a chelator such as transferrin that can inhibit fungal growth.

Isolation and characterization of a rubredoxin and two ferredoxins from Desulfovibrio africanus

Rubredoxin and two distinct ferredoxins have been purified from Desulfovibrio africanus. The rubredoxin has a molecular weight of 6000 while the ferredoxins appear to be dimers of identical subunits of approximately 6000 to 7000 molecular weight. Rubredoxin contains one iron atom, no acid-labile sulfide and four cysteine residues per molecule. Its absorbance ratio A278/A490 is 2.23 and its amino acid composition is characterized by the absence of leucine and a preponderance of acidic amino acids. The two ferredoxins, designated I and II, are readily separated on DEAE-cellulose. The amino acid compositions of ferredoxins I and II show them to be different protein species; the greater number of acidic amino acid residues in ferredoxin I than in ferredoxin II appears to account for separation based on electronic charge. Both ferredoxins contain four iron atoms, four acid-labile residues per molecule. Spectra of the two ferredoxins differ from those of ferredoxins of other Desulfovibrio species by exhibiting a pronounced absorption peak at 283 nm consistent with an unusual high content of aromatic residues. The A385/A283 absorbance ratio of ferredoxins I and II are 0.56 and 0.62, respectively. The N-terminal sequencing data of the two ferredoxins clearly indicate that ferredoxins I and II are different protein species. However, the two proteins exhibit a high degree of homology.