Developmental changes in the duration of attention to unfamiliar stimuli in the rat

The purpose of the present study was to examine developmental changes in the duration of attention to novel auditory stimuli in rats from infancy to adulthood. In all experiments, the cardiac component of the orienting response was used as the index of attention. In the first experiment 16-, 23-, 30-, and 75-day-old rats were exposed to a novel auditory stimulus for 60 s. Animals of all four ages exhibited a marked decrease in heart rate in response to this stimulus. Although there were no significant effects of age on the magnitude of the cardiac response, there were dramatic developmental differences in the persistence of the response. The 16-day-olds maintained a decrease in heart rate for the entire stimulus period, whereas heart rate returned to baseline in the 75-day-olds after only 40 s. The duration of the cardiac response of the 23- and 30-day-olds was between these extremes. In Experiments 2A and 2B the effect of stimulus complexity on duration of the cardiac response was examined. Increasing stimulus complexity prolonged the deceleratory response in the 30-day-olds (Experiment 2A), and decreasing stimulus complexity decreased the duration of the cardiac response in the 16-day-olds (Experiment 2B). The results of these experiments were discussed in the context of Cohen's and Porges's two-phase theories of attention. The findings demonstrate that the initial attention-getting or reactive phase of attention did not change with age, but that the duration of the attention-holding or sustained phase decreased substantially during development.

Emergency center arteriography

From 1983 through 1989, 1,882 emergency center arteriograms were performed on 1,802 patients suspected of having peripheral vascular injuries. The most common indication for emergency center arteriography (ECA) was the proximity of an injury to a major vascular structure. This was the only indication in 1,712 injured extremities (91%). There were 1,510 true negative arteriograms, 294 true positives, 7 false negatives, and 14 false positives. Accordingly, the sensitivity was 95.5% and the specificity was 97.7%. The remaining 57 arteriograms were either equivocal or technically inadequate. Further evaluation of these patients uncovered an additional 11 vascular injuries. Operative intervention was required for 196 (64.3%) injuries detected by emergency arteriography. The remaining 109 injuries were considered minor and were not repaired. No complications developed in 91 patients (88%) with minor vascular injuries who were available for a mean follow-up duration of 12 months. One thousand forty-eight patients (69.4%) with negative arteriograms were followed for a mean of 18 months, and no vascular complications were noted. Emergency center arteriography is a rapid, accurate, and cost-effective technique. It is of particular value in detecting the presence of occult arterial injuries when proximity of a major vascular structure is the sole indication for arteriography. When formal arteriographic support is either unavailable or time consuming, ECA is recommended.

Developmental constraints on the expression of behavioral and heart-rate orienting responses: II. The role of ambient temperature

The effect of ambient temperature on the expression of behavioral and heart-rate orienting responses to a novel olfactory stimulus was examined in rats 1-18 days of age. There was no effect of ambient temperature on the behavioral orienting responses at any age. Ambient temperature did influence the expression of the heart-rate orienting response and did so differentially as a function of age. The implications of these findings for developmental models of attention and cognition are discussed.

Outcome for delayed operation of penetrating colon injuries

It has been stated that delay in operative repair of penetrating injuries to the gastrointestinal tract will result in a high rate of complications related to infection. To test this assertion, a group of patients with penetrating injuries to the colon were analyzed who had operative repair delayed (usually because of triage considerations) more than 6 hours after admission to the hospital. Nine hundred six patients who survived at least 48 hours after injury were divided into two groups. The immediate group of 769 patients was treated within 6 hours of admission and the delayed group of 137 patients was treated more than 6 hours after admission. The mortality for the immediate group was 4.0% vs. 1.5% for the delayed group. Colon-related infectious complications, defined as abscess or colon suture-line failure, occurred in 10% of the immediate group and 4.4% of the delayed group. To eliminate the effect of associated injuries, the group of patients with colon injuries only was analyzed separately. There was no mortality for 128 patients with colon injuries only operated on within 12 hours of injury, and the colon-related infectious morbidity rate was 3%. Eleven patients with colon injuries only were treated after 12 hours with a mortality of 9% and colon-related infectious morbidity of 18%. These data demonstrate that even patients with fecal contamination can have operative repair delayed for up to 12 hours without undue morbidity related to infection.

Resting and total energy expenditure in patients with ischemic heart disease

Total energy expenditure (TEE) was measured by doubly labeled water in 13 preoperative patients undergoing elective coronary artery surgery and compared to resting energy expenditure (REE) measured by indirect calorimetry (IC) calculated from the Harris-Benedict (HB) formula or from formulas based on midarm circumference and arm muscle circumference. Mean REE measured by IC and calculated from the HB, midarm circumference, arm muscle circumference formulas were 62, 75, 62, and 69%, respectively, of TEE measured by doubly labeled water. REE measured by IC correlated significantly with that predicted by the HB (p = 0.006) but not the anthropometric formulas. The relationship between REE derived from anthropometric predictive formulas and REE measured by IC is altered in ischemic heart disease.

Effects of cardiac surgery and intraoperative hypothermia on energy expenditure as measured by doubly labelled water

Total energy expenditure (TEE) was measured over two 10-day periods, before and after operation in 16 patients undergoing coronary artery surgery and randomized to have cardiopulmonary bypass with an intraoperative blood temperature of either 28 or 20 degrees C. TEE was measured with doubly labelled water containing stable isotopes of hydrogen and oxygen to allow calculation of TEE over fixed periods from the differential rate of excretion of the two isotopes. Results were available for eight patients in the 28 degrees C group but for only seven in the 20 degrees C group (one patient in this group was excluded as the temperature allocated was not achieved). The groups were similar with respect to body-weight and lean body mass. The 20 degrees C group received more grafts than the 28 degrees C group, resulting in an increase in cross-clamp and bypass times. Mean preoperative TEE was similar in both groups. The mean difference in fractional turnover rates of hydrogen and oxygen was not significantly different in the postoperative period. There was a non-significant increase in the mean 10-day postoperative TEE, calculated in total calories, of 4.7 per cent in the 28 degrees C and 5.1 per cent in the 20 degrees C group. When changes in postoperative TEE were calculated according to lean body mass, the mean increases were respectively 3.7 and 3.2 per cent. Cardiac surgery utilizing cardiopulmonary bypass and intraoperative hypothermia results in only a modest increase in postoperative TEE. In this study a more profound level of intraoperative hypothermia did not influence the change in postoperative TEE.

Developmental constraints on the expression of behavioral and heart-rate orienting responses: I. The role of cardiosomatic coupling

The ontogeny of behavioral and heart-rate orienting responses to a novel olfactory stimulus was examined in three experiments. The results of Experiment 1 demonstrated that behavioral responses to the olfactory stimulus were observed as early as Day 1, although heart-rate deceleration in response to the stimulus was not observed until Day 9. In Experiment 2, bradycardia was observed in 6-day-old pups if stimulus-elicited motor activity was reduced with haloperidol. Thus, the developmental asynchrony in the expression of behavioral and heart-rate orienting responses was due, at least in part, to cardiosomatic coupling in the very young animal. The results of Experiment 3 demonstrated that although cardiosomatic coupling interferes with the expression of the heart-rate orienting response very early in development, it has increasingly less impact over the course of the preweaning period.

Effects of four beta-adrenergic receptor antagonists on male rat sexual behavior

Antihypertensive medication has been reported to cause serious sexual side effects in men. Frequently mentioned as causing sexual dysfunction are beta-adrenergic receptor antagonists. The purpose of this study was to examine in detail the effects of beta blockers on adult male rat sexual behavior. Thirty minutes following a single subcutaneous injection of propranolol, pindolol, atenolol or labetalol, mating tests were conducted. The mixed beta 1- and beta 2-adrenergic antagonists, propranolol and pindolol, profoundly inhibited male sexual behavior. At the 5 and 10 mg/kg doses, propranolol inhibited ejaculatory behavior to the extent that only 9.1 and 8.3% respectively showed the behavior while pindolol reduced this behavior to 36.4% (16 mg/kg). These drugs also adversely affected various parameters of behavior in a dose-dependent manner. The selective beta 1 antagonist, atenolol, had only minor effects and labetalol even less so at the doses tested. It was suggested that the strongly inhibitory effects of propranolol and pindolol on male rat sex behavior may well be due to their 5-HT1A antagonistic binding properties rather than their beta-antagonistic properties.

Infant mortality and undernutrition in the squatter settlements of Karachi

The socio-demographic and biological processes contributing to infant mortality and undernourishment were studied in five urban squatter settlements of Karachi. All those families who had experienced an infant death in the past 2 years (N = 106) were recruited into the study. Comparative children were selected by random numbers with geographical matching from families with at least one live infant and without a history of infant deaths in the past 2 years. The comparison children were weighed and those found underweight (27 per cent) were studied for the presence of risk factors. Forty-one per cent of all deaths were in the neonatal period, and in 47 per cent of cases deaths had occurred in infants with a birth order of 5 and above. Age, duration of breast feeding, birth interval, and the live/dead status of the previous sibling were significant biological variables accounting for 23 per cent of the variance for survival. Socio-economic status accounted for 22 per cent of the variance and health-seeking behaviour (antenatal care, immunization, etc.) for 28 per cent. Sixty-eight per cent of those underweight were more than 6 months old. Age, female sex, birth interval less than 24 months, duration of breast feeding, adolescent mother, alive/dead status of the previous child were significant influences accounting for 12 per cent of the variance. Socio-economic status and health seeking behaviour were also important determinants, but not to the same extent as in the case of infant death.

Retroperitoneal vascular injury

Retroperitoneal vascular injuries are among the greatest challenges that confront the surgeon. Problems in resuscitation, exposure, and repair are numerous. Techniques to improve such perioperative tactics result in improved survival.

Plasma and dialysate levels of pefloxacin and its metabolites in CAPD patients with peritonitis

Six patients with acute peritonitis undergoing continuous ambulatory peritoneal dialysis for end-stage renal failure received an 800 mg loading dose of pefloxacin mesylate orally followed by 400 mg twice daily orally for 10 or 21 days. Plasma and dialysate levels of both pefloxacin and its metabolites were measured. Plasma levels in excess of the MIC for all infective bacteria were achieved within 90 min and in dialysate within 4 h. No significant accumulation of pefloxacin or its metabolite norfloxacin was noted. However, both serum and dialysate levels of the metabolite pefloxacin N-oxide rose continuously during treatment. Plasma and dialysate levels of all three agents fell rapidly during the five days after treatment had stopped. No major side effects were observed, although two patients developed Achilles tendonitis.

Disruption and recovery of the orienting response following shock or context change in preweanling rats

Previous research has shown that placement of preweanling rats in an unfamiliar environment inhibits both heart rate and behavioral orienting responses to an auditory stimulus, and that the orienting response gradually reappears during the following 15 min. Four experiments designed to evaluate two potential explanations of this effect were conducted. If the arousal induced by an unfamiliar environment disrupts sensory information processing, so should the arousal induced by mild electric shock. In two experiments, the orienting response was inhibited in proportion to number of shocks received and rate of recovery was comparable to that observed in the unfamiliar environment. New environments also contain many unfamiliar stimuli which may overload the rats' limited information processing capacity. In two experiments a change in environmental stimulation was shown to inhibit the orienting response. Recovery of the orienting response followed the same time course as that seen following shock or placement in an unfamiliar environment. Although the results of this study clearly demonstrate environmental inhibition of the orienting response, they provide little support for either the "arousal" or the "information overload" hypotheses of orienting response inhibition. The implications of these data for current theoretical conceptualizations of the orienting response are discussed.

Joseph Rogers and the reform of workhouse medicine

Images

Coping with the suicidal elderly: a physician's guide

Advancing age is associated with a markedly increased risk of suicide. In the United States, one fourth of all suicides are carried out by citizens age 60 or older. The majority of American elders who commit suicide use a firearm to do so. Most suicidal elders look to their primary care physician for help, although they may not directly express their plan. Therefore, physicians must be alert to clues. By far the principal risk factor for suicide is major depression. The risk is heightened by recent losses, alcohol or drug abuse, psychosis, cognitive decline, and chronic disease. Hopelessness, anhedonia, self-reproach, guilt, and a formed lethal plan are signs of a life-threatening suicidal crisis which requires urgent intervention. Physicians must act decisively in recognition of the fact that suicidality is a transient, treatable condition.

Effect of maternal presence on the cardiac and behavioral responses to shock in rats as a function of age

In two experiments the effects of the presence of an anesthetized lactating dam on the developing rat's response to a series of mildly painful shocks was examined. Both cardiac and behavioral responses to the shock stimulus were recorded. In the first experiment animals were tested at either 16, 20, or 24 days of age. The presence of the anesthetized dam markedly reduced the behavioral response to shock of the 16-day-old but not the older rats. A similar pattern of results was obtained with the shock-elicited tachycardia. The second experiment replicated these results with the 16-day-old rat and also demonstrated that being shocked in the presence of a lactating dam influences the animal's reaction to a subsequent series of shocks given when it is alone. The results of these two experiments are discussed in terms of other studies that have examined the influence of maternal presence on the developing animal's response to stressful or painful stimuli.

The material tensile strength of convex-faced aspirin tablets

The material tensile strength of a range of convex-faced tablets, compacted under controlled conditions at pressures of 40 and 320 MPa from a size fraction of acetylsalicylic acid, has been assessed. The calculation of the tensile strength sigma 1, from observed fracture loads obtained in diametral compression testing, is based on the equation derived by Pitt et al (1988), namely: (formula; see text) where P is the fracture load, D is the tablet diameter, t is the overall tablet thickness and W is the central cylinder thickness. The strength of a tablet of a given shape compacted at 320 MPa was between two and four times greater than that of a similar tablet compacted at 40 MPa. For the thicker tablets (W/D greater than or equal to 0.2) the material tensile strength was practically independent of shape. For the thinner tablets (W/D = 0.1) the material tensile strength varied considerably with face-curvature, showing a maximum for each of the two compaction pressures at a D/R value of 0.67.

A large trial of intravenous Conray 325 and Niopam 300 to assess immediate and delayed reactions

The trial was designed as an investigation into the incidence of both immediate and delayed reactions to the intravenous administration of Conray 325 (sodium iothalamate) (844 patients) and Niopam 300 (iopamidol) (855 patients) for urographic examination. Information was obtained from questionnaires returned by patients about a week after their examination, with a response rate of 81%. Significant differences were found in the incidences of both types of reactions to the two media with respect to nausea and vomiting, arm pain, and taste in the mouth, which was commoner in patients receiving Conray 325, whereas the incidence of delayed skin rashes and parotid swelling was commoner with Niopam 300. The occurrence of a flu-like illness, so-called "iodism", was found to be equal for the two contrast media.

Inspector General James Barry MD: putting the woman in her place

Images

ACTH produces long-lasting recovery following partial extinction of an active avoidance response

Recent data suggest that ACTH administration produces recovery of an extinguished passive avoidance response at an unusually long injection-to-test interval. The present experiment sought to explore further the durability of recovery by examining the effect of ACTH following extinction of one-way active avoidance. Adult rats were injected with 16 IU ACTH, an equivalent volume of the ACTH vehicle gel, or saline 48 h after a previously learned active avoidance response was partially extinguished. Different groups from each treatment condition were tested 15 min, 24 h, or 7 days after injection. ACTH improved avoidance performance at all injection-to-test intervals relative to saline and vehicle gel injected controls. These data indicate that unlike reversal of other types of performance decrements, in which the effect of ACTH appears to be transient, administration of the hormone following an extinction treatment can produce enduring improvement of avoidance performance.

Congenital metastatic cervical teratoma: diagnostic and management considerations

Cervical teratomas in the newborn are uncommon and difficult management problems, as their natural history and prognosis are not well defined. Existing or potential airway obstruction is usually the main concern in acute management of these patients. Total excision is essential to avoid local recurrence in benign lesions, and a small but present risk of malignancy can result in death from metastatic lesions which appear later. A unique case of neonatal malignant cervical teratoma with large congenital metastatic lesions present in liver, lung, and buttocks was successfully managed. Magnetic resonance imaging (MRI) was invaluable, both in delineating these lesions and in planning a four-stage curative resection of all macroscopic disease. Such a case has not been reported previously.

Effects of in vitro incubation on a zona binding site found on murine spermatozoa

Murine cauda epididymal sperm possess a site, the acceptor, on the plasma membrane over the apical cap region of the acrosome which recognizes both a proteinase inhibitor of seminal vesicle origin and homologous zonae. The acceptor site may participate in both capacitation and zona binding. This presentation explores the effect of in vitro incubation in a medium known to induce capacitation on the binding capabilities of this site. Approximately 80% of fresh cauda epididymal sperm will bind the seminal inhibitor in vitro. Incubating sperm, pretreated with inhibitor for 2 hr in a medium (M199-M) known to support capacitation, reduces by 60% the number of sperm showing evidence of the inhibitor. No such decrease is seen when sperm are incubated in a medium (M199) that does not support capacitation. During the 2-hr incubation in either medium, 60-70% of the sperm retain two diverse components on the plasma membrane over the acrosome: a receptor for the Fc portion of IgG and an epitope recognized by a monoclonal antibody to the acceptor site. These observations suggest that the plasma membrane in the acrosome region of the cell remains structurally intact during incubation. Furthermore, sperm retain the ability to bind the seminal inhibitor during incubation. After a 2-hr incubation in M199-M, sperm pretreated with heat-solubilized zonae no longer bind the inhibitor. These sperm, however, retain the plasma membrane over the acrosomal cap region. When the sperm are incubated in M199, no decrease in inhibitor binding due to zona treatment is noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Effective thrombolytic therapy of aortic thrombosis in the small premature infant

Aortic thrombosis in the very-low-birthweight premature infant has remained both a diagnostic and a therapeutic dilemma. Nine small infants were evaluated for symptoms of extremity and/or visceral ischemia. All were found to have aortoiliac thrombosis most likely related to indwelling umbilical artery catheters. Diagnostic and therapeutic options were evaluated. An angiogram obtained through the catheter was found to be the most effective diagnostic technique. Local infusion of intra-arterial streptokinase (50 U/kg/h) directly into the clot for 36 hours resulted in resolution of ischemic symptoms. No complications were encountered with the use of this protocol.