Extensive patch tracheoplasty with a silicon "T" tube stent in a 7-month-old infant

Congenital tracheal stenosis is difficult to manage. We describe the combination of an extensive patch tracheoplasty and silicon "T" tube stenting performed in a 7-month-old infant following classical repair of a coexisting pulmonary artery sling.

Measuring long-term outcome after traumatic brain injury

We report the results of the first stage of development of an instrument to measure long-term functional outcome after traumatic brain injury. The instrument focuses on both the person with a disability and the impact on the family caregiver. We illustrate the early stages of instrument development, focusing on one approach to standardized reviewer feedback to evaluate content validity. The results of the pilot testing are discussed in terms of: purpose, instrument construction, and clinical utility. While the complete details of the instrument are not presented, example items are used as illustration. A number of methodological issues in instrument development in rehabilitation are described including the logistics of reviewer feedback, the use of family caregivers in instrument development and the reliability of self-report in brain-injured population.

Prevalence of multiple sclerosis in Barrhead County, Alberta, Canada

A prevalence study of multiple sclerosis (MS) was carried out in the town of Barrhead and surrounding county of Barrhead, in Alberta, Canada. The prevalence rate for clinically probable/definite multiple sclerosis on January 1, 1990 was 196/100,000. The average annual incidence rates for patients living in the area at onset were 1.31/100,000 for 1950-59, 4.97/100,000 for 1960-69, 3.77/100,000 for 1970-79, and 4.22/100,000 for 1980-89. Fifty percent of the patients were relapsing-remitting. Sixty percent were still walking without assistance. The female-to-male ratio was 1:1. Mean current age, age at onset and duration of illness were 49, 27 and 22 years respectively. The majority of patients (40%) experienced multiple symptom onset. Fifty percent were of single ethnic origin (either British or German); the rest were predominantly North European combinations. Forty percent of patients reported another MS relative. MS had affected the work status of 60% of the patients, 15% of whom were confined to an extended care centre.

Simulation of motion on the skin. V. Effect of stimulus temporal frequency on the representation of moving bar patterns in primary somatosensory cortex of monkeys

1. To assess the mechanisms used by cortical neurons to sense motion across the skin, we applied pulsatile stimuli to a series of adjacent positions on the glabrous skin of the hand using a computer-controlled OPTACON stimulator. We describe responses of 129 single neurons in primary somatosensory cortex of alert monkeys to a horizontal bar pattern that was displaced proximally or distally in 1.2-mm steps at 10-, 20-, and 40-ms intervals (100, 50, and 25 Hz, respectively). These frequencies span the range in which apparent motion is transformed perceptually in humans from a smooth uninterrupted sweep into a series of distinct pulses that are resolved as separate events. The experiments are thus designed to decipher the neural correlates distinguishing continuous motion from discrete taps. 2. Cortical receptive fields mapped with moving bar patterns spanned 5-24 rows on the tactile array (16.2 +/- 5.4, mean +/- SD). Over 40% of the fields encompassed 18 or more rows (greater than or equal to 21.6 mm), allowing these neurons to integrate spatial information from an entire image displayed on the OPTACON. Cortical receptive fields are considerably larger than those of mechanoreceptors mapped with the same moving bar patterns (4.2 +/- 2.3 rows, mean +/- SD), reflecting convergent inputs in subcortical and cortical relays. Responses were either relatively uniform across the field or strongest at the initial point of entry, depending on the frequency of stimulation. A sharply defined field center was absent from most of the cells recorded in this study. 3. Temporal frequency of stimulation appears to be a major determinant of cortical firing patterns. Low-frequency stimuli are more effective in activating cortical neurons, producing more spikes per sweep and greater phase-locking to individual stimuli than do high frequencies. The total spike output of cortical neurons is proportional to the pulse interval over the range 10-40 ms, increasing linearly by an average of 5.9 spikes/10-ms increase in pulse period. Peak firing rates and modulation amplitude are also highest when pulses are presented at long intervals, falling significantly as the stimulation frequency rises. The reduction in firing at high pulse rates is apparently due to central mechanisms, as both rapidly adapting and Pacinian corpuscle afferents display nearly constant spike outputs and uniform sensitivity within the field when tested with identical bar patterns. Central networks thus behave as low-pass filters, reducing cortical responses to rapidly applied sequential stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

Pulmonary phaeohyphomycosis due to Xylohypha bantiana

We encountered a rare case of pulmonary phaeohyphomycosis due to Xylohypha bantiana documented by culture. This dematiaceous (darkly pigmented) fungus is primarily neurotropic. It usually produces phaeohyphomycosis of the central nervous system but may also involve the skin and subcutaneous tissues. The patient, a 49-year-old woman with a history of steroid-treated inflammatory bowel disease, was found to have a lung nodule consisting of granulomas that contained dark hyphal fragments that stained positively with the argentaffin reaction. Surgical excision was curative and appears to be the treatment of choice.

Influence of medical history on assessment of at-risk infants

The influence of knowledge of their medical history on the assessment of at-risk infants was examined. Two at-risk infants, one with a high-risk medical history and one with a low-risk history, were assessed and videotaped using the Movement Assessment of Infants. 41 physical therapists were randomly assigned to assess the videotaped examinations in four groups with different knowledge of the infants' histories (high-risk infant with actual or low-risk history; low-risk infant with actual or high-risk history). The clinical significance of the difference in total risk scores between knowledge conditions of a high-risk history and a low-risk history was greater for the low-risk infant. The higher mean total risk score for the low-risk infant assessed with a high-risk history suggests that false positive results could occur which may alter parents' perceptions and interactions with the infants and consequently influence their development.

Decreased seasonal mesor of platelet 3H-imipramine binding in depression

Seasonal cycles of platelet 3H-imipramine binding were compared in 49 endogenous unipolar depressed patients and 20 normal volunteers. A significant sinusoidal component was detected in the Bmax of binding in both patients and controls with similar amplitudes and seasonal peaks. However, the yearly average (mesor) of the patient group was significantly lower (20.0%) than that of the normal controls. The results support earlier claims of a diminished platelet binding in endogenous depression and indicate that this decrease was still evident in the presence of a 48.2% (controls) to 65.8% (patients) seasonal variation. Control Bmax values were normally distributed about a best-fit mean (cosinor fit). In contrast, patient values appeared to be bimodally distributed with one mode that was similar to controls and one mode that was substantially lower. In general, psychiatric symptoms failed to distinguish between patients with high and low platelet binding and no correlation was found between Bmax and severity of illness (HAM-D).

Risk factors by onset age in multiple sclerosis

Some investigators have suggested that there are different forms of multiple sclerosis (MS) based on onset age, and that each has a different etiology. 173 Canadian MS patients were matched to controls on age, gender, race and risk zone prior to age 15. Data were collected on: age at onset, gender, initial symptom, disability level, residence history and family background. Three onset age subgroups (early, intermediate and late) were derived. Matched-pair logistic regression analysis indicated that rural residence, use of well water and an MS family history distinguished between patients and controls overall, but showed no significant interaction with onset age. A family history of diabetes distinguished between patients and controls with evidence of age interaction, in that this risk factor decreased in importance as onset age increased.

Emotional stress and coping in multiple sclerosis (MS) exacerbations

Ninety-five pairs of MS patients in exacerbation and remission were compared on emotional stress in the previous three months. Patients in exacerbation scored higher on emotional disturbance and intensity of stressful events than patients in remission, but lower on frequency of compensating uplifts. There was also a tendency for more patients in exacerbation than remission to favour emotion-focused coping techniques over problem-solving or social support. Whether patients building to an exacerbation over-react to various events or unresolved emotional stress precipitates exacerbations, MS patients might benefit from counselling in stress reduction techniques.

Use of bioassay methods to evaluate mutagenicity of ambient air collected near a municipal waste combustor

An ambient air sampling study was conducted around a municipal waste combustor; a primary goal was to develop procedures and methods to evaluate the emissions of organic mutagens resulting from incomplete combustion of municipal waste. The products of incomplete combustion from incineration include complex mixtures of organics, particularly polycyclic aromatic compounds, which are present after atmospheric dilution and cooling in emissions as semi-volatile or particle bound organic compounds. Combustion emissions are generally recognized as a potential cancer risk since they contain many carcinogenic and mutagenic polycyclic aromatic hydrocarbons. Analyzing such a complex mixture for the presence of even a few selected chemicals is difficult and provides risk information on only a fraction of the chemicals present. Bioassay methods, however, may be directly applied to evaluate the mutagenic and potential carcinogenic activity of the complex organics from combustion emissions. The Salmonella (Ames) assay was used to determine the mutagenicity associated with particles from ambient air collected near a municipal waste combustor. Dose-response data was generated, and mutagenicity concentrations were calculated to demonstrate the utility of bioassay in assessing the potential impact of emissions from municipal waste combustion. This phase of study quantified mutagenicity concentrations in ambient air but did not detect organic mutagens that could be attributed to incinerator emissions.

Changes in platelet 3H-imipramine binding with chronic imipramine treatment are not state-dependent

One month of imipramine treatment increased both the Kd and Bmax of platelet 3H-imipramine binding in 11 endogenous unipolar depressed patients. Continued treatment (13 weeks) of 5 patients subsequently lowered the Bmax values of 2 patients who had initially shown the largest increases, so that binding was no longer significantly elevated after 13 weeks. The observed changes in Kd but not in Bmax, could be explained by the carryover of tightly bound drug to the binding assay, although neither of the measures were correlated with plasma imipramine levels. Posttreatment Bmax (4 weeks) values were inversely related to plasma cortisol levels, although a weak but positive correlation was found before treatment. No significant change was found in plasma cortisol with treatment. Clinical responses were not related to cortisol or Bmax changes, although optimal improvement was associated with extreme values (high and low) of pretreatment Bmax. The present results, obtained with imipramine, and similar results obtained after nortriptyline and electroconvulsive shock by others, suggest that at least some antidepressants may induce transient changes in the Bmax of platelet binding that are independent of affective state.

Self-reported depressive symptomatology, mood ratings, and treatment outcome in sleep disorders patients

Based on self-rating questionnaire evaluation of symptoms of major affective disorder, 67% of patients who presented to a major sleep disorders center reported an episode of depression within the previous 5 years, and 26% described themselves as depressed at presentation. Furthermore, patients with sleep apnea, narcolepsy, or sleep-related periodic leg movements all averaged high rates of self-reported depressive symptomatology, which suggests that sleep disorders should be considered in the differential diagnosis of affective disorders, and vice versa. Change scores on the Profile of Mood States were obtained for four subgroups of patients who were undergoing conventional treatment. Significant improvement in scores was observed in obstructive sleep apneics treated surgically and in patients with sleep-related periodic leg movements placed on clonazepam, but not in narcoleptics placed on a stimulant or in insomniacs with chronic use of sedative-hypnotic drugs who were withdrawn from sleep medications. Differential improvement in POMS scores after treatment for different sleep disorders could mean that the relationship to mood disturbance differs for different sleep disorders.

Multiple sclerosis in childhood: clinical profile in 125 patients

Multiple sclerosis (MS) has its usual onset in early adult life (average age of 30 years), but age at clinical onset varies considerably. The implications of the age of onset on the clinical presentation and course of MS are unclear. This population-based retrospective study presents data from a group of 125 patients with onset of MS before age 16 years and can thus be considered as representative of MS occurring in childhood. It demonstrates that childhood MS is more frequent in girls, that it very often has a relapsing-remitting course, that initial bouts usually involve afferent structures of the central nervous system, that recovery from these is often complete, and that the pace of the disease is slow.

Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys

S. Warren, H. A. Hamalainen, and E. P. Gardner, “Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys.” It was incorrectly stated that Orban and co-workers(J. Neurophysiol. 45: 1059–1073, 1981) attributed direction selectivity to cortical neurons having a direction index (DI) ge 20. Orban et al. actually used a weighted average of DIs and defined cells with a mean DI (MDI) above 50 as direction selective. Their criterion for direction selectivity was stricter and not less stringent, as stated in the paper. This error does not alter any of the data or conclusions of Warren et al.

Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys

S. Warren, H. A. Hamalainen, and E. P. Gardner, “Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys.” It was incorrectly stated that Orban and co-workers ( J. Neurophysiol. 45: 1059–1073, 1981) attributed direction selectivity to cortical neurons having a direction index (DI)≥20. Orban et al. actually used a weighted average of DIs and defined cells with a mean DI (MDI) above 50 as direction selective. Their criterion for direction selectivity was stricter and not less stringent, as stated in the paper. This error does not alter any of the data or conclusions of Warren et al.

A population-based study of multiple sclerosis in twins

Results from studies of twin concordance in multiple sclerosis have not conclusively differentiated between environmental and genetic factors that determine susceptibility to the disease. Published studies that have been based on case finding by public appeal have been characterized by difficulties in ascertainment. The data reported here are from a large population-based study of multiple sclerosis in twins, in which ascertainment has been relatively unbiased and the cooperation of patients nearly complete. A total of 5463 patients attending 10 multiple sclerosis clinics across Canada were surveyed. Twenty-seven monozygotic and 43 dizygotic twin pairs were identified, and the diagnosis of multiple sclerosis was verified by examination and laboratory investigation. Seven of 27 monozygotic pairs (25.9 percent) and 1 of 43 dizygotic pairs (2.3 percent) were concordant for multiple sclerosis. The concordance rate for 4582 nontwin siblings of patients at two multiple sclerosis clinics was 1.9 percent, closely paralleling the concordance rate in dizygotic twins. To the extent that the difference in concordance rates between monozygotic and dizygotic twins indicates genetic susceptibility, the results of this study show a major genetic component in susceptibility to multiple sclerosis.

Objective classification of motion- and direction-sensitive neurons in primary somatosensory cortex of awake monkeys

In order to classify movement-sensitive neurons in SI cortex, and to estimate their relative distribution, we have developed a new simple method for controlled motion of textured surfaces across the skin, as well as a set of objective criteria for determining direction selectivity. Moving stimuli were generated using 5 mm thick precision gear wheels, whose teeth formed a grafting. They were mounted on the shafts of low-torque potentiometers (to measure the speed and direction of movement) and rolled manually across the skin using the potentiometer shaft as an axle. As the grafting wheel was advanced, its ridges sequentially contacted a specific set of points on the skin, leaving gaps of defined spacing that were unstimulated. This stimulus was reproducible from trial to trial and produced little distention of the skin. Three objective criteria were used to categorize responses: the ratio of responses to motion in the most and least preferred directions [direction index (DI)], the difference between mean firing rates in the two directions divided by the average standard deviation [index of discriminability (delta'e)], and statistical tests. Neurons were classified as direction sensitive if DI greater than 35, delta's greater than or equal to 1.35 (equivalent to 75% correct discrimination by an unbiased observer), and firing rates in most- and least-preferred directions were significantly different (P less than 0.05). Good agreement was found between the three classification schemes. Recordings were made from 1,020 cortical neurons in the hand and forearm regions of primary somatosensory cortex (areas 3b, 1 and 2) of five macaque monkeys. Tangential motion across the skin was found to be an extremely effective stimulus for SI cortical neurons. Two hundred eighty six of 757 tactile neurons (38%) responded more vigorously to moving stimuli than to pressure or tapping the skin. One hundred twenty-one cells were tested with moving gratings and were classified according to their ability to differentiate movement in longitudinal and transverse directions. Responses to the moving gratings resembled those observed when stroking the skin with brushed, edges, or blunt probes. Three major types of firing patterns were found: motion sensitive, direction sensitive, and orientation sensitive. Motion-sensitive neurons (37%) responded to movement in both longitudinal and transverse directions with only slight difference in firing rates and interval distributions. Responses throughout the field were fairly uniform, and no clear point of maximum sensitivity was apparent. Direction-sensitive neurons (60%) displayed clear preferences for movement in one or more directions.4

Coding of the spatial period of gratings rolled across the receptive fields of somatosensory cortical neurons in awake monkeys

In order to measure the texture coding capabilities of motion-, direction-, and orientation-sensitive neurons in SI cortex, we rolled wheels with surface milled gratings across their receptive fields. Gratings of spatial periods 0.8-9.6 mm were presented in pseudorandom order; each was tested 5-20 times in the distal, proximal, radial, and ulnar directions. Thirty eight cortical neurons were studied with three to eight different gratings in order to determine the effect of spatial period on neuronal firing rates. While all 38 cells had their firing rates modulated by motion of the gratings, only 11 neurons were able to distinguish changes in its spatial period. These cells had small receptive fields located on the hand. Most motion-sensitive neurons showed little effect of spatial period on firing rates and had relatively flat frequency response curves. One showed decreased firing to spatial periods over the range 0.8-6.4 mm; three others increased their firing rates over the range 0.8-3.2 mm, followed by a decline in activity to larger spatial periods. Direction- and orientation-sensitive neurons showed only minor changes in firing rates as a function of spatial period. Sixteen cells showed flat frequency response functions, three showed increased firing rates, and four decreased firing rates as spatial period of the grating increased. Direction and orientation preferences were maintained over the range 0.8-9.6 mm for all 23 neurons tested. Although four cells showed a drop in direction index (DI) as the spatial period was increased, none showed a loss of direction sensitivity, as DI was greater than 35 for all gratings tested. Two neurons showed increased firing to motion in the last-preferred direction and two others decreased firing in the best direction. The remaining 19 neurons showed parallel effects of texture in all directions. Some motion-sensitive neurons showed weak direction preferences when tested with fine gratings; these preferences disappeared with coarser gratings, due to increased responsiveness to motion in the least-preferred direction. These data demonstrate that movement-sensitive neurons do not require continuous trajectories across the skin but instead sequential activation of points aligned in a specific path. Cortical neurons appear capable of integrating information from points separated by up to 9 mm, as long as they are presented in the appropriate temporal sequence. Firing rates of direction- and orientation-sensitive neurons are more profoundly modified by changes in the direction of motion across the skin, and the temporal order of stimulation, than by alterations in the spatial characteristics of the moving stimulus.(ABSTRACT TRUNCATED AT 400 WORDS)

The somatosensory thalamus of the raccoon: properties of single neurons responsive to light mechanical stimulation of the forepaw

These studies were undertaken to characterize the discharge properties of single neurons of the raccoon thalamic ventrobasal complex (VB) that respond to light mechanical stimulation of the glabrous surfaces of the forepaw. Microelectrodes were used to record the extracellular activity of 146 cells in anesthetized raccoons, and all neurons were histologically verified as falling within or along the boundaries of VB. Sixty-one neurons were tested for activation by electrical stimulaton of primarily somatosensory cortex. Of these, 88% were antidromically activated, 5% were synaptically activated, and the remaining 7% were unresponsive. Out of the total sample of 146 neurons, 136 had peripheral receptive fields (RFs) that were restricted to glabrous skin and revealed properties of modality and place-specificity predictable through knowledge of properties of primary mechanoreceptive afferents. Rapidly adapting (RA) neurons accounted for 77% of this modality-place-specific sample, while 19% were slowly adapting (SA), and 4% revealed properties indicative of input from Pacinian afferents (Pc). Absolute displacement thresholds were comparable for RA and SA neurons (range = 6-415 micron). Palmar RF areas (range = 3.3-328 mm2) were significantly larger than digital RF areas (range = 0.5-98.2 mm2). As defined by exponents (b) of power functions relating instantaneous discharge frequency to displacement ramp velocity, SA neurons formed a single, homogeneous group (range of values of b = 0.633-0.720). However, RA neurons fell into three distinct groups: those showing relatively steep functions (b = 0.559-0.938), those showing relatively flat functions (b = 0.146-0.334), and those showing discontinuous, or step, functions. A small number of neurons (7% of total sample) revealed "complex" properties, not predictable from knowledge of properties of primary afferents. These included five neurons whose RFs encompassed both glabrous and hairy skin, and several linear orientation, or "tactile edge," detectors. The present results, in conjunction with those of earlier studies of the raccoon dorsal column-medial lemniscal system, lead to the conclusion that different types of information transformation are emphasized at different levels of the system. Intramodality convergences (increases in RF area) occur primarily within the cuneothalamic relay, while changes in the coding of quantitative information are primarily a function of VB neurons. The appearance of linear orientation detectors--a type of tactile "feature detector"--indicates that the synthesis of information regarding complex spatial properties of stimuli has its beginnings within the somatosensory thalamus.

Extra intestinal influences on exhaled breath hydrogen measurements during the investigation of gastrointestinal disease

During the clinical investigation of patients with gastrointestinal disease by exhaled breath hydrogen measurement, the occurrence of inexplicable variations in recorded hydrogen values led to a search for extra intestinal factors which were capable of adversely influencing breath hydrogen concentration and impairing the diagnostic accuracy of the test. Serial breath samples were collected from normal subjects under a variety of conditions which might occur during routine clinical study, including, hyperventilation, exercise, cigarette smoking, and carbohydrate ingestion. Breath hydrogen concentrations were consistently reduced by hyperventilation (p less than 0.01) and exercise (p less than 0.05). Cigarette smoking, in contrast, caused a marked rise in measured breath hydrogen (p less than 0.01), as did oral carbohydrate (p less than 0.05). Prior bactericidal mouthwash abolished this carbohydrate associated rise, suggesting that the hydrogen was the result of fermentation by oropharyngeal bacteria. Because, in all instances, the changes in breath hydrogen were of sufficient magnitude to interfere with data interpretation, it is recommended that these factors are eliminated, whenever possible, from conditions of study.

Differential sensitivity to airpuffs on human hairy and glabrous skin

To compare the relative sensitivities of glabrous and hairy skin, we measured reaction times (RTs) and detectability (d') of airpuffs delivered to the hairy dorsum and glabrous thenar eminence of the hand of six human subjects. In contrast to previous studies with mechanical contact stimuli, airpuffs applied to hairy skin were detected with equal or greater fidelity than airpuffs tested on glabrous skin. Mean RTs to three simultaneously applied airpuffs were significantly shorter (p less than .005) on hairy skin in five of six subjects, and in 74% of paired sessions; no significant difference in mean RTs was observed in 16% of the sessions. The superiority of hairy skin was less evident, however, when single airpuffs were tested, as significantly shorter responses were observed on only 45% of the paired sessions, and nearly identical responses on 38% of the sessions. Detectability of airpuffs (d'), which is independent of the value of RTs, was identical on hairy and glabrous skin at high airpuff intensities (1,600 dyn), and superior (n = 4) or equal (n = 2) on hairy skin with low airpuff intensities (800 dyn). Spatial summation was more pronounced on hairy than on glabrous skin. Three simultaneously presented airpuffs produced significantly shorter RTs than one airpuff in 85% of the paired sessions on hairy skin, but on only half of the sessions on glabrous skin. The spatial distribution of stimulus force was less important on hairy skin, as three low-intensity airpuffs produced the same or shorter RTs than one high-intensity airpuff. By contrast, on glabrous skin, detectability was significantly better when force was concentrated at a single point (1 X 1,600 dyn) than when diffused over a wide skin area (3 X 800 dyn). The enhanced sensitivity of hairy skin to airpuffs appears partially attributable to hair motion in the airstream. After hair removal by chemical depilation, detectability of airpuffs was reduced on hairy skin to a level equal to or below that on glabrous skin. Spatial summation on the depilated skin corresponded to that observed on the intact hairy skin, indicating that depilation did not abolish intensity discrimination, but rather lowered the overall sensitivity of hairy skin. These results show that hair follicle units form a very sensitive detection mechanism on hairy skin of the human hand, similar to that provided by Meissner's and Pacinian afferents in glabrous skin. These findings with airpuffs provide the first example of a tactile stimulus that is less effective for mechanoreceptors in glabrous skin than in hairy skin.(ABSTRACT TRUNCATED AT 400 WORDS)

Distribution of cerebellar mossy fibers arising from neurons of the raccoon main cuneate nucleus

The present study demonstrates that fibers originating in the raccoon main cuneate nucleus are not segregated in specific cortical regions of target cerebellar folia as reported in studies of the cat cuneocerebellar tract. This observation supports the hypothesis that exteroceptive and proprioceptive divisions of the raccoon cuneocerebellar tract do not exist as distinct structural entities. The findings of this study do not preclude the possibility that projections from the external and main cuneate nuclei are segregated within the cerebellar cortex on the basis of functional modality rather than nucleus of origin.

Somatosensory evoked potentials (SEPs) and cortical single unit responses elicited by mechanical tactile stimuli in awake monkeys

The origins of surface recorded evoked potentials have been investigated by combining recordings of single unit responses and somatosensory evoked potentials (SEPs) from the postcentral gyrus of 4 alert macaque monkeys. Responses were elicited by mechanical tactile stimuli (airpuffs) which selectively activate rapidly adapting cutaneous mechanoreceptors, and permit patterned stimulation of a restricted area of skin. Epidurally recorded SEPs consisted of an early positive complex, beginning 8-10 msec after airpuff onset, with two prominent positive peaks (P15 and P25), succeeded by a large negative potential (N43) lasting 30 msec, and a late slow positivity (P70). SEPs, while consistent in wave form, varied slightly between monkeys. The amplitude of the early positive complex was enhanced by increasing the number of stimulated points, or by placing the airpuffs in the receptive fields of cortical neurons located beneath the SEP recording electrode. SEP amplitude was depressed when preceded 20-40 msec earlier by a conditioning stimulus to the same skin area. Single unit responses in areas 3b and 1 of primary somatosensory (SI) cortex consisted of a burst of impulses, beginning 11-12 msec after the airpuff onset, and lasting another 15-20 msec. Peak unitary activity occurred at 12-15 msec, corresponding to the P15 wave in the SEP. No peak in SI unit responses occurred in conjunction with the P25 wave. Although SI neurons fired at lower rates during P25, the lack of any peak in SI unit responses suggests that activity in other cortical areas, such as SII cortex, contributes to this wave. Most unit activity in SI cortex ceased by the onset of N43, and was replaced by a period of profound response depression, in which unit responses to additional tactile stimuli were reduced. We propose that the N43 wave reflects IPSPs in cortical neurons previously depolarized and excited by the airpuff stimulus. Late positive potentials (P70) in the SEP had no apparent counterpart in SI unit activity, suggesting generation at other cortical loci.

Somatosensory thalamocortical connections in the raccoon: an HRP study

In the North American raccoon (Procyon lotor), representations of the glabrous surfaces of the hand digits are found within separate subnuclei of the thalamic ventrobasal complex (VB) and on separate subgyri of the somatosensory cortex (SmI). In the present study, the retrograde transport of horseradish peroxidase from SmI to VB was utilized to study relationships between physiologically identified cortical subgyri and somatotopically corresponding thalamic subnuclei. Single large or multiple small injections confined to a single gyral crown led to retrograde labeling of large groupings of cells filling the entire VB subnucleus for the appropriate digit. In the aggregate, the regions of label appeared as thin, wedge-shaped sheets extended in the dorsoventral and anteroposterior dimensions, but flattened mediolaterally, and curving to form a laterally directed convexity; these appear to correspond to the lamellae of monkey VB described by others. These large injections led to labeling of approximately 80% of all large (18-30-micron diameter) cells within the lamella. Single, small, focal injections of a gyral crown led to variable amounts of labeling, ranging from an entire digital lamella to only a small focal cluster of cells. No evidence was obtained for the existence of anteroposteriorly extending "rods" of cells, as reported in primates. Finally, there was a sparse, but consistent labeling of cells of the posterior nuclear group (Po) following gyral crown injections. These results are in agreement with expectations based on prior electrophysiological studies of raccoon VB and SmI, as well as prior anatomical studies of thalamocortical relationships.

Necrotizing enterocolitis and hemolysis associated with Clostridium perfringens

Two newborns had necrotizing enterocolitis (NEC) and severe hemolytic anemia. Clostridium perfringens was identified in the peritoneal fluid of both infants, supporting the previous association of C perfringens with hemolysis reported in adult patients. Infants with NEC and hemolytic anemia should be aggressively treated with surgical debridement and high-dose parenteral penicillin G potassium. Similarly, Gram's stain of peritoneal fluid and resected bowel at laparotomy for NEC may be useful for early identification of the primary organism.

Effect of pheochromocytoma and hypophysectomy on blood pressure and catecholamines in NEDH rats

The New England Deaconess Hospital (NEDH) rat provides a valuable model with which to study pheochromocytoma (P); 59% of male rats 700 to 900 days old and 81% of those 900 days or older developed spontaneous P. One transplantable P (P259), when implanted into other NEDH rats, markedly increased plasma norepinephrine and dopamine as well as blood pressure, and usually caused death within 4 weeks. Even without P, about 83% of NEDH rats became hypertensive by 131/2 weeks of age and remained moderately hypertensive until 2 years of age when some animals developed spontaneous P and hypertension became severe. Whether a common mechanism is responsible for early appearance of hypertension and later development of P remains to be determined. Hypophysectomized NEDH rats remained normotensive or slightly hypotensive despite marked elevations of plasma norepinephrine and dopamine caused by P259 implantation; furthermore, survival was prolonged to 3 months. Catecholamine concentrations in plasma and RBC were usually quite similar, indicating that red blood cells play a significant role in inactivating circulating catecholamines. Unlike the normal adrenal, P259 in NEDH rats contains mainly norepinephrine and dopamine with little epinephrine; it appears that P259 is deficient in the enzyme phenylethanolamine-N-methyltransferase (PNMT), which converts norepinephrine to epinephrine. Why hypophysectomy prevents hypertension and prolongs life in rats with P259 implants is unclear; adrenal cortical and thyroid deficiency may play a role. Preliminary observations indicate that hypophysectomy can prevent spontaneous development of P in NEDH rats.

Effect of pheochromocytoma and hypophysectomy on blood pressure and catecholamines in NEDH rats

The New England Deaconess Hospital (NEDH) rat provides a valuable model with which to study pheochromocytoma (P); 59% of male rats 700 to 900 days old and 81% of those 900 days or older developed spontaneous P. One transplantable P (P259), when implanted into other NEDH rats, markedly increased plasma norepinephrine and dopamine as well as blood pressure, and usually caused death within 4 weeks. Even without P, about 83% of NEDH rats became hypertensive by 131/2 weeks of age and remained moderately hypertensive until 2 years of age when some animals developed spontaneous P and hypertension became severe. Whether a common mechanism is responsible for early appearance of hypertension and later development of P remains to be determined. Hypophysectomized NEDH rats remained normotensive or slightly hypotensive despite marked elevations of plasma norepinephrine and dopamine caused by P259 implantation; furthermore, survival was prolonged to 3 months. Catecholamine concentrations in plasma and RBC were usually quite similar, indicating that red blood cells play a significant role in inactivating circulating catecholamines. Unlike the normal adrenal, P259 in NEDH rats contains mainly norepinephrine and dopamine with little epinephrine; it appears that P259 is deficient in the enzyme phenylethanolamine-N-methyltransferase (PNMT), which converts norepinephrine to epinephrine. Why hypophysectomy prevents hypertension and prolongs life in rats with P259 implants is unclear; adrenal cortical and thyroid deficiency may play a role. Preliminary observations indicate that hypophysectomy can prevent spontaneous development of P in NEDH rats.

Emotional stress and the development of multiple sclerosis: case-control evidence of a relationship

One hundred multiple sclerosis (MS) patients were compared to hospital controls, for life stress prior to onset age in the MS patients and controls did not differ on: the happiness of their childhood environment; their pre-onset age reaction to life's problems (relaxed and taking things in stride/tense or easily upset); or on their tendency to seek professional help with an emotional problem. However significantly more MS patients than controls reported that they were under unusual stress in the 2 yr period prior to onset age; and the MS patients described a greater number of stressful life situations, or single events, than the controls.

Mesothelioma relative to asbestos, radiation, and methylcholanthrene

The carcinogenicity of chrysotile asbestos fibers (Canadian and Rhodesian) for the mesothelium of pleura and peritoneum of NEDH rats was explored by injection of 2 mg of asbestos fibers suspended in saline intratracheally, intrapleurally, or intraperitoneally, with or without ancillary radiation treatment (1,000 rad to the whole body of parabiont rats or 2,000 rad to the right thorax of single rats), or alternatively, by injection of asbestos plus 1 mg of 3-methylcholanthrene. A highly significant incidence of mesothelioma (3.8%) was noted in 159 rats treated with asbestos alone, as compared with 0.1% in 1,417 control rats. Additional treatment with radiation or 3-methylcholanthrene increased this incidence to 11.8% and 25.5%, respectively, the latter increase alone being significant at the .01 level of probability.

Increasing incidence of adenocarcinoma of the lung

Review of the histology of 219 lung cancers initially diagnosed at Lutheran General Hospital, Park Ridge, Illinois, in 1963-1967 and 1974-1976, confirms the increasing incidence of adenocarcinoma. This is due to an increase of adenocarcinoma in men. In women, the incidence of adenocarcinoma was higher than squamous carcinoma in the earliest period (44% adeno, 18% squamous). The percentage of women with lung cancer has also significantly increased from 19% to 31%, which increases the overall incidence of adenocarcinoma of the lung. As the number of women with lung carcinoma has increased, there has been no change in the percentage of adenocarcinoma in women.

Multiple sclerosis and associated diseases: a relationship to diabetes mellitus

One hundred multiple sclerosis (MS) patients and hospital controls were compared for coexisting illnesses, and other illnesses among their family members. The patients and controls were compared for allergy, migraine, and cancer among themselves and for a family history of these illnesses. The findings were negative. However a relationship was found between multiple sclerosis and diabetes mellitus. More MS patients than controls were either diabetic or reported a blood relative with diabetes. MS patients who reported another blood relative with MS were also more likely to report a family history of diabetes mellitus than MS patients who had no other relative with multiple sclerosis.

Comparative effects of aspartate and glutamate during myocardial ischemia

The effects of amino acids aspartate (Asp) and glutamate (Glu) on recovery of contractile function and preservation of compliance were studied in globally ischemic, isolated, blood-perfused cat hearts. Ischemia-induced declines in contractility and compliance were measured with an intraventricular fluid-filled balloon. Asp and Glu were delivered to isolated hearts in physiological salt solution (PSS) containing 10 mM glucose, just prior to, and intermittently during (every 15 min for 1 min) 1 h of normothermic ischemia. Isolated hearts which received Asp and Glu showed recoveries of left ventricular (LV) developed pressure of 79 +/- 8 and 50 +/- 7% of their preischemic values, respectively, compared to 34 +/- 7% in hearts perfused only with PSS. These alterations of contractile function were paralleled by changes in LV compliance. The addition of amino-oxyacetate, and aminotransferase inhibitor, to Asp- containing PSS markedly attenuated the beneficial effects of this amino acid. The results indicate that certain amino acids can protect the ischemic myocardium, presumably through effects on intermediary metabolism.

Risk of cancer subsequent to low-dose radiation

Prominent among media items related to the Three Mile Island episode were prophecies of future cancers. The credibility of some of these estimates are discussed. The average person has been exposed by the age of 50 to 2.5 rad (0.025 Gy) from natural background. We define low doses as under 25 rad (0.25 Gy). The most heavily exposed members of the general population during the Three Mile Island event received 83 mrad (0.83 mGy). Those exposed to 2500 mrad (25 mGy) would show no pathologically recognizable effects of radiation though there is evidence that chromosomal damage may occur with doses about 1 rad (0.01 Gy). An official stated among the consequences of the Three Mile Island accident that two additional cancer deaths would result. No epidemiologist could detect such an increase in the population at risk. It has been generally agreed that the linear hypothesis is useful for determining protection standards, not prognosis. Objective criteria for pathologic diagnosis of cause-effect relations are presented.

Renin requires a structural alteration prior to activation by renal kallikrein

Renal kallikrein may be the physiologic protease which activates renin. In vitro activation of plasma inactive renin by renal kallikrein, however, requires prior dialysis of plasma to pH 3.3, which is thought to destroy endogenous plasma kallikrein inhibitors. We present evidence that low pH directly alters renin to facilitate its activation by renal kallikrein. Untreated normal plasma was combined with pH 3.3 dialyzed and neutralized plasma and incubated with semipurified human renal kallikrein 2.3 X 10(-2) to 4.6 IU/ml, pH 7.5, 25 degrees C for 1h. All concentrations activated renin in acid-treated plasma; whereas, in untreated plasma 4.6 IU/ml renal kallikrein was ineffective. In combinations of untreated and acid-treated plasma, the percent renin activated by renal kallikrein was equal to the percent acid-dialyzed plasma present. When acid-treated plasma was combined with buffer, activation was complete and quantitatively the same as in the untreated and acid-treated plasma combinations. The data suggest inactive renin itself is altered structurally by pH 3.3; this change in the renin molecule is necessary for kallikrein activation. Renal kallikrein may not be the sole in vivo activator of renin.

A life-cycle conference series; education for general practice

An all around educational programme for general practice trainees involving a conference and seminar cirriculum was developed, based on a life-cycle concept. In addition to emphasizing the study of usual life stresses and crisee for individuals and families, the programme encouraged the contribution of resource people from many related medical disciplines and also from the non-health sciences. Detailed planning allowed the structuring of the conference over an academic year. Clearly defining the objectives for each meeting led to effective evaluation and enhanced the educational process.

Some observations on a program attaching public health nurses to family physicians' offices

This study examined a program attaching public health nurses to specific family physicians practicing in the community. It compared the work of attached and nonattached public health nurses in both the urban and rural sections of a health district in Ontario, Canada. It found that attached nurses receive a greater proportion of their referrals from family physicians, see a greater percentage of elderly patients, and deal with proportionately more psychosocial cases. The study also indicated that the attached public health nurse does not complain of physician misuse of her services and that, once a referral has been made, communication between the physician and public health nurse improves.

Quantitation of left ventricular wall motion in normal subjects: comparison of various methods

Computer-assisted analysis of percent change in the square root of area in each of 12 consecutive 30-degree, pie-shaped ventricular segments was obtained in 48 normal subjects who underwent cardiac catheterization and left ventriculography. The information obtained permitted establishment of objective confidence limits for normal left ventricular regional wall motion. As an index of dynamic changes in segmental wall motion, the percent change in the square root of area method compared favorably with existing radius, area, hemichord, and chord methods. It also possessed a variety of theoretical advantages over these techniques: 1) large numbers of points were analyzed, 2) wall motion disorders in all areas except base were evaluated, 3) taking the square root of area's percent change provided both area information with least splay and an average measure of radius.

Health planners and local public finance--the case for revenue sharing

Little attention has been paid by health planners or researchers to questions of local public finance. However, a review of the literature concerning general revenue sharing (GRS) funds indicated that about $400 million per year from this source is spent on health services and resources. GRS funds, about $6.4 billion per year, are distributed to more than 39,000 State, county, and city governments. The 1976 amendments to the General Revenue Sharing Act eliminated restrictions on the use of the funds, and they can be employed as matching funds for other Federal monies. An exploratory study of the use of GRS funds for health purposes was conducted in several localities, with particular attention to the health systems agencies. Its results confirmed that there are wide variations among localities in the use of revenue-sharing funds to support health services. Also, not only did the health systems agencies' officials have little impact on the allocation of revenue sharing funds, but only in one locale had an HSA official taken a direct role in the budgetary process. Health planners, who were interviewed during the study, described what they considered their agencies' proper role in local budgetary matters.