Search PubMed⌕ Search

Biomedical subjects

J C Johnson

Publications and source records attributed to J C Johnson.

At least 181 records · Page 10Linked to original sources
PubMed1976

Anterior infarctional changes occurring during mid and late ventricular activation detectable by surface mapping techniques.

This is a comparative body surface potential map study of 26 patients with a recent acute anterior myocardial infarction. The mean plus or minus two standard deviations (+/- 2 SD) for the voltage distribution was established at 5 msec intervals throughout the cardiac cycle in 30 normal subjects at each of 142 recording sites. Instances in which a patient's potential distribution fell outside the normal range were analyzed as to location, duration and intensity against the expected time course of ventricular activation. Only four patients had departures from the normal distribution confined to the Q time zone. Twenty patients had not only Q time zone abnormalities, but had areas of both positivity and negativity exceeding +/- 2 SD, which occurred well after 30 msec. Two patients with clearly documented diagnostic Q waves during the first few days of hospitalization had lost these findings by the date of body surface mapping. They did retain, however, departure map findings demonstrating significant abnormalities occurring between 30 and 60 msec after onset of ventricular activation. These changes occurring in the mid and late time zones of the activation sequence are not detectable by conventional electrocardiography or vectorcardiography, yet present a strikingly apparent finding by this technique of analysis and display.

Action Potentials↗
PubMed1976

Cerebrospinal fluid prolactin: a reflection of abnormal prolactin secretion in patients with pituitary tumors.

Cerebrospinal fluid prolactin levels were determined in 33 patients with pituitary disease, 3 pregnant women at term and 30 control subjects. Prolactin which was immunologically similar to the human prolactin standard was detected by radioimmunoassay in the CSF of most of these subjects. Elevated serum and CSF PRL concentrations were found in three pregnant subjects and in twelve patients with putuitary tumors. Ten patients with pituitary tumors had serum PRL concentrations greater than their corresponding CSF PRL levels. A significant correlation was noted between the elevated serum and CSF prolactin levels in the twelve hyperprolactinemic patients which suggested that the CSF prolactin concentration was influenced by the serum PRL level. Two patients with pituitary tumor however, had CSF prolactin concentrations higher than their serum levels, which suggested that direct secretion of prolactin from the tumor to the CSF can also occur. Three patients with chromophobe adenomas had normal serum PRL concentrations and elevated CSF prolactin levels which differentiated them from fifteen patients with the primary empty sella syndrome who had normal serum and CSF prolactin levels. The finding of normal CSF prolactin levels in the primary empty sella patients argues against the postulate that the diaphragma sellae significantly influences CSF pituitary peptide concentrations.

Acromegaly↗
PubMed1976

Pituitary tumors and hyperprolactinemia.

Hyperprolactinemia was demonstrated in eight of nine patients with clinical evidence of pituitary tumors without acromegaly or Cushing syndrome. Hourly sampling for 24 hours disclosed elevation of serum prolactin concentrations, whereas, measurable serum growth hormone levels were found rarely. Although eight of these patients were hypersecreting prolactin, only four of them were lactating. Prolactin secretion was characterized by moderate hourly fluctuations of serum levels and absence or blunting of the normal sleep-related augmentation of secretion. Patients with the highest serum prolactin concentrations tended to have the largest pituitary tumors, as indicated by pneumoencephalography. In two patients followed-up with serum prolactin determinations after treatment, a fall in serum prolactin concentrations correlated with clinical improvement. Future study will hopefully establish the value of serum prolactin determinations in following tumor growth before and after pituitary ablative therapy.

Adolescent↗
PubMed1976

Chromophobe adenoma and chiasmal syndrome without enlargement of the bony sella.

Four cases of chiasmal syndrome resulting from chromophobe adenoma with normal-sized sella turcica are reported. The predominantly suprasellar growth of these tumors was probably the result of a well-pneumatized sphenoid sinus and/or a congenitally deficient diaphragma sellae. In patients with chiasmal syndrome, a high suspicion of a surgically treatable lesion must be maintained in spite of radiographs showing a normal-sized sella. In spite of the difficulties presented by normal variations, subtle findings should be searched for on the plain films and given additional weight in the patient with a chiasmal syndrome. An aggressive diagnostic work-up, including pneumoencephalography with thin-section tomography, should be pursued in all such patients before accepting some alternate explanation, such as demyelinating disease, for visual impairment.

Adenoma, Chromophobe↗
PubMed1975

Polytomoencephalography of the optic chiasm and adjacent structures.

The addition of polytomography considerably increases the sensitivity of pneumoencephalography. The chiasmatic area lends itself particularly well to investigation by polytomoencephalography. In a series of 28 patients, the transverse dimension of the optic chiasm ranged from 4 to 20 mm, with a mean of 18 mm. The posterior portion of the chiasm tended to be U-shaped; its anterior portion's shape was that of a dumbbell. Intrachiasmatic tumors distort and enlarge the chiasm. The diaphragma sella is also particularly well evaluated by this technique. The study is safe, reliable, and can be repeated as needed.

Adolescent↗
PubMed1975

Ensiled diet containing processed municipal garbage and sorghum forage for heifers.

Diets of similar proximate analysis formulated with a base of sorghum forage and primarily supplemented with equivalent dry matter of 18.4% of aerobically digested municipal garbage (garbage diet) or 17.5% of cottonseed hulls (control diet) were ensiled for 52 days and then individually and group fed to 16 dairy heifers for 56 and 35 days. Apparent digestibility of dry matter, crude protein, ether extract, crude fiber, and nitrogen-free extract in garbage and control diets averaged 54.2 and 47.4, 50.0 and 41.3, 62.0 and 65.1, 53.1 and 42.3, and 61.8 and 54.5% as determined by chromium oxide technique. Potential advantages from digestibility of the garbage diet appeared to be nullified by a 12% depression of dry matter intake and a consequent deterioration of feed efficiency. Dry matter intakes of garbage and control diets during the 56-day comparison were 1.98 and 2.25% of body weight and daily gains of .42 and .57 kg required 13.9 and 11.8 kg dry matter per kilogram of gain. Over the 91 days of combined comparison feeding, the .62 kg of average daily gain from control diet was 32% above the .47 kg from the garbage diet.

Animal Feed↗
PubMed1975

Differential responses of Duroc, Hampshire, and crossbred pigs to a superimposed experimental infection with the intestinal threadworm, Strongyloides ransomi.

In both spring and fall, 12 Duroc, 12 Hampshire, and 12 Duroc times Hampshire F1 weanling pigs all reared under the same management were fed in pens of 3 to slaughter weights. Three Duroc and 4 Hampshire boars, essentially unrelated within breed, were used in sampling the breeds. Swine herd management allowed pig infection with Strongyloides ransomi and Ascaris suum, but neither clinical nor subclinical parasitism was evident in the herd. Pigs were percutaneously exposed by pens within breed and season, half to none (control) and half to 3,000,000 (exposed) S. ransomi infective larvae, Breed, treatment, and seasons were prominent sources of variation in pig response. Breeds failed to respond alike to parasitism in respect to experimental periods and exposure levels. This interaction response (P smaller than 0.01) showed that S. ransomi egg production increased rapidly for all breed groups but decreased quicker and greater in Durocs, slowest and least in Hampshires, with cross breds intermediate in these respects. The 2.0830 for mean of log A. suum EPG from exposed Durocs was near double that of control Durocs but the mean for exposed Hampshires was less than half that for controls; crossbreds tended to be intermediate in this respect. Daily gains of 0.70 and 0.73 for Durocs and crossbreds were similar (P greater than 0.10) but averaged 11.7% more (P smaller than 0.05) than the 0.64 kg for Hampshires and gains by control pigs were 20.6% above (P greater than 0.01) that of exposed pigs. Exposed pigs required more feed per kg of gain (P greater than 0.05) than control pigs (3.60 vs. 3.33 kg). Comparison of relative gains and feed efficiences of control and exposed pigs among and within breed groups supported the position that a superimposed exposure of 3,000,000 S. ransomi larvae was more severe for Hampshires, intermediate for crossbreds, and least severe for Durocs.

Animals↗