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Biomedical subjects

D G Johnson

Publications and source records attributed to D G Johnson.

At least 181 records · Page 10Linked to original sources
PubMed1981

Hypothalamic control of endocrine thermogenesis.

Hypothalamic and ruminal cooling raised serum thyrotropin (TSH), adrenocorticotropin (ACTH), norepinephrine (NE), and glucose in conscious goats in 20 degree C ambient temperature. Cooling of the preoptic anterior hypothalamus (POAH) for 2 h initially evoked shivering and vasoconstriction, leading to 1.5 degree C rise in rectal temperature (Tr). Pituitary-thyroid activation by POAH cooling was shown by peak rises in TSH of 60% at 40 min, in triiodothyronine (T3) of 54% at 80 min, and in thyroxine (T4) of 40% at 140 min. At 60 min, ACTH and NE peaked at 57 and 65%, respectively. TSH, ACTH, and NE declined during the 2nd h of POAH cooling as Tr plateaued; when POAH cooling was stopped, these hormones fell below basal level as vasodilation and panting restored Tr to normal. In contrast to the core hyperthermia evoked by POAH cooling, ruminal intubation with O degree C water (1 liter/10 kg) led to general hypothermia, Tpoah and Tr falling 1.6 degree C at 40 min. Pituitary-thyroid responses were less but ACTH and NE more, compared with POAH cooling. TSH peaked at 37% at 20 min, T3 at 55% at 60 min, and T4 at 18% at 200 min. ACTH peaked at 250% at 30 min and NE at 120% at 20 min. Thermosensitive neurons in the POAH seem to mediate more sensitive and complete control over TSH than over ACTH, or NE release, whereas extrahypothalamic core thermosensitivity (e.g., brain stem, spinal cord, abdomen) may influence ACTH and NE more than TSH release.

Adrenocorticotropic Hormone↗
PubMed1981

Effect of multiple trauma on outcome of pediatric patients with neurologic injuries.

In a 3-year period, 95 patients with severe head injury (unconsciousness greater than 6h duration) were treated at our institution. Of these, 46 patients (48%) had isolated head injury and 49 (52%) had head injury plus severe multiple trauma. Multiple trauma was scored using the Modified Injury Severity Scale. All patients in the multiple trauma group had at least one additional area of severe injury. Severity of head injury, judged by Glasgow Coma Score, presence of mass lesions, abnormal posturing or flaccidity, impaired or absent oculocephalic reflexes, and fixed, dilated pupils, was much greater in the isolated head injury group. In spite of this, poor outcome (death or vegetative/severe disability) was 2 1/2 times as frequent in the multiple trauma group. Shock, refractory hypoxemia and sepsis were contributing factors in this increased morbidity and mortality. Increasing Modified Injury Severity Scale scores were associated with increased morbidity and mortality.

Adolescent↗
PubMed1980

Excessive mortality and causes of death in morbidly obese men.

A group of 200 morbidly obese men (average weight, 143.5 kg; age, 23 to 70 years) were admitted to a weight control program between 1960 and 1977 and were followed up for a mean period of 7 1/2 years. There was complete follow-up until the termination of the study or until death for 185 men. Fifteen men were followed up for fractional periods. Fifty of the 200 died during the course of the study. Life-table techniques, comparing the mortality among the obese with that among men in the general population, demonstrated a 12-fold excess mortality in the obese in the age group 25 to 34 years and a sixfold excess in the age group 35 to 44 years. This ratio diminished with advancing age. Cardiovascular disease was reported as the cause of death more frequently and malignancies less frequently than they were for men in the US general population.

Adult↗
PubMed1980

Patterns of gastroesophageal reflux in children following repair of esophageal atresia and distal tracheoesophageal fistula.

We studied gastroesophageal reflux (GER) in 25 children between 3 and 83 mo post-repair of esophageal atresia and distal tracheoesophageal fistula (EATEF). The incidence of GER was determined by 18-24 hr pH monitoring of the distal esophagus and gastroesophageal scintiscan following the ingestion of 99mTc sulfur colloid in apple juice. Gastric emptying was also assessed in 20 children. Only 17 of 25 (68%) children had significant GER by esophageal pH monitoring, and 13 of 20 (65%) had significant GER by gastroesophageal scintiscan. Significant GER was found in 10 of 12 (83%) patients wih recurrent vomiting, respiratory symptoms or severe esophagitis. Three of these 10 patients required an operation to control GER. Significant GER occurred in continuous, discontinuous and mixed patterns. The discontinuous pattern was seen in 11 of 17 (65%) children, and was associated with slow gastric emptying. The only factor during the repair of EATEF that subsequently was associated with a higher incidence of significant GER (88% vs. 59%) and slow gastric emptying (11.2 +/- 4.2% vs. 25.9 +/- 3.7% gastric emptying at 30 min, p less than 0.05) was excessive tension at the esophageal anastomosis. Many children with EATEF do not have significant GER, but in those with significant GER slow gastric emptying seems to be important.

Esophageal Atresia↗
PubMed1980

Experimental subglottic stenosis: histopathologic and bronchoscopic comparison of electrosurgical, cryosurgical, and laser resection.

Controversy continues over the optimal method of resecting subglottic stenosis. Electrosurgery, cryosurgery and laser resection have all had some clinical success. We sought to compare these treatment methods in experimentally-created subglottic stenosis. Subglottic strictures were created transbronchoscopically in newborn lambs by electrocoagulating a rim of mucosa. Four weeks later, all had 20 to 90% occlusion documented bronchoscopically. Control animals were found to have dense submucosal fibrosis in the cricoid area. Remaining experimental animals were treated with: (1) electrosurgical resection; (2) cryosurgical treatment; (3) Neodymium-yag (Nd:Yag) laser at 20 watts; (4) Nd:Yag laser with 40 watts; or (5) carbon dioxide laser at 10 watts. Animals from each group were sacrificed at 5 and 30 days postresection and the tracheas were examined grossly and microscopically. Animals sacrificed at 30 days postresection were bronchoscoped at weekly intervals. Cryosurgical and electrosurgical resection resulted in 1-3 mm of thermal damage adjacent to the margin of resection at 5 days post-treatment. Mucosal ingrowth and healing were rapid and there was no development of stenosis or damage to underlying structures. Use of the Nd:Yag laser resulted in 10-20 mm of surrounding damage in animals sacrificed at 5 days. At 30 days posttreatment, there was mucosal healing but extreme underlying damage and redevelopment of stenosis at the level of treatment. The carbon dioxide laser-treated animals showed thermal damage present up to 2 mm in depth from resected areas at 5 days post-treatment. Mucosal regeneration proceeded rapidly. This study indicates that electrosurgical and cryosurgical resection for experimental subglottic stenosis create minimal thermal damage and are associated with comparably acceptable rates of mucosal ingrowth and healing. The carbon dioxide laser created comparable to slightly decreased thermal damage but suffers at present from lack of optimal visualization of the subglottic lesion.

Animals↗
PubMed1980

Surgery in children with gastroesophageal reflux and respiratory symptoms.

We reviewed our seven-year experience in 63 children with an operation to control gastroesophageal reflux and respiratory symptoms. The age at operation, sex, major associated disorders, and control of vomiting in this group of children were compared with another group of 72 children without respiratory symptoms who also had an antireflux operation during the same period. Associated central nervous system, pharyngeal, or esophageal disorders were common in both groups. Vomiting was controlled in 96% of patients. Fifty-six of 61 (92%) children had at least partial relief of respiratory symptoms postoperatively. The complete relief of these symptoms was more likely in patients without major associated disorders (97% vs 59% P = 0.0009). Central nervous system disorders were present in most children with incomplete resolution of respiratory symptoms. It appears that a significant number of affected infants and children may have respiratory difficulties unrelated to the presence of GER.

Adolescent↗
PubMed1980

Gastroschisis and omphalocele. An eight-year review.

Until recently confusion has existed concerning the clinical features and surgical treatment of gastroschisis and omphalocele. Since 1971 75 infants with these abdominal wall defects have been treated at our institution. Significant differences (p equal to 0.001 in all instances) were noted between the two diseases. Gastroschisis occurred twice as often as omphalocele and is increasing in frequency. Prematurity was commonly seen with gastroschisis (65%). While the overall incidence of malformations associated with gastroschisis was low (23%), the vast majority of the additional malformations were jejunoileal or colonic atresias. The mortality rate was 12.7% among gastroschisis patients, with only one death attributable to prematurity. All other deaths were preventable, indicating that even lower mortality rates are feasible. Omphalocele was associated with a 23% incidence of premature birth but associated anomalies were present in 66% of the patients. Major cardiac (52%) and chromosomal defects (40%) predominated. In addition, 17% of omphalocele patients had either Cantrell's pentalogy or cloacal/bladder exstrophy. The mortality rate in omphalocele (34%) was nearly three times that of gastroschisis. Nine of ten patients who died from omphalocele died either from major cardiac or chromosomal disease. However, in patients without cardiac or chromosomal defects the survival rate was 94%.

Abdominal Muscles↗
PubMed1980

Comparison of glucagon responses to 2-deoxy-D-glucose and hypoglycemia in man.

2-Deoxy-D-glucose (2DG), by competitive inhibition of glucose utilization, produces a state of intracellular glucopenia with resultant activation of both the sympathetic and parasympathetic branches of the autonomic nervous system. We have investigated the relationship between the activation of the autonomic nervous system caused by this drug and glucagon secretion. Subjects experienced symptoms identical to those observed during true hypoglycemia and demonstrated a marked rise in both gastric acid secretion and urinary epinephrine excretion. Mean immunoreactive glucagon (IRG) levels rose only slightly post-2DG (maximal mean increment, 18 pg/ml). Insulin-induced hypoglycemia, although eliciting a similar increase in urinary epinephrine excretion, was followed by a severalfold increase in IRG. Thus, although hypoglycemia and 2DG induced similar discharge of the autonomic nervous system, the glucagon response to hypoglycemia was much greater. These observations provide strong evidence that marked increases in sympathetic and parasympathetic discharge in man are weak alpha-cell stimuli and further support the hypothesis that the rise in IRG that occurs during hypoglycemia is not mediated primarily via the autonomic nervous system.

Adult↗
PubMed1980

Hypothermia in iron deficiency due to altered triiodothyronine metabolism.

Iron-deficient rats become hypothermic and have an excessive catecholamine response when exposed to an ambient temperature of 4 degrees C. This is not due to changes in body insulation, since thickness is unaltered, since differences persist after removal of hair, and since cutaneous vasoconstriction is intact. On the other hand, oxygen consumption of iron-deficient animals at 4 degrees C is reduced, 39 +/- 3 ml . kg-1 . min-1 compared to 63 +/- 2 in control animals. Thyroxine (T4) values at 4 degrees C were 4.34 +/- 0.20 microgram/dl sera as compared to control values of 3.6 +/- 0.32. Triiodothyronine (T3) values of iron-deficient animals in the cold were 48 +/- 6.8 ng/dl as compared to 72 +/- 5.6 in control animals. Treatment of iron-deficient animals with iron was shown to normalize the plasma T3 response at 4 degrees C within 6 days. Thyroidectomized iron-deficient animals injected with T3 did not show hypothermia at 4 degrees C, whereas thyroidectomized iron-deficient animals injected with T4 showed hypothermia, increased catecholamines, and decreased T3 levels as compared to non-iron-deficient animals similarly treated. It is proposed that iron deficiency impairs conversion of T4 to T3 and that this is primarily responsible for the hypothermia observed.

Animals↗
PubMed1979

Patterns of postcibal gastroesophageal reflux in symptomatic infants.

Symptomatic infants displayed three patterns of gastroesophageal reflux after drinking apple juice (20 ml/kg or 300 ml/m2 of body surface area). The type I pattern occurred in patients who had continuous postcibal gastroesophageal reflux, large hiatal hernias and frequently required an antireflux operation. A functional motility disorder suggesting delayed gastric emptying appeared to be important in infants with discontinuous reflux (type II pattern). These infants had frequent gastroesophageal reflux for only 2 3/4 hours postcibally, antral-pylorospasm, increased low esophageal sphincter pressures, and a high incidence of pulmonary symptoms and non-specific watery diarrhea. The mixed (type III) pattern of gastroesophageal reflux occurred in a small number of infants and exhibited features of both type I and II patterns.

Child, Preschool↗