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Biomedical subjects

R B Freeman

Publications and source records attributed to R B Freeman.

At least 73 records · Page 4Linked to original sources
PubMed1986

Pupillary responses to syntactic ambiguity of sentences.

Pupillary responses have proven to be reliable physiological correlates of cognitive effort in a variety of tasks, including language processing. To investigate the relation between psychological and syntactic complexity 20 syntactically ambiguous sentences, balanced for bias, were presented to 16 subjects, while their pupil size was continuously measured. These sentences could be read as verb oriented (syntactically more complex) or object oriented (syntactically less complex). Principal components analysis of pupillary movements revealed that verb-oriented readings, resulted in greater pupillary dilations than object-oriented readings, indicating that syntactically more complex sentences, as determined via a formal grammar, require greater cognitive effort in processing. This is viewed as further evidence for the notion that syntactic and psychological complexity are related. High- and low-bias sentences did not induce comparable differences in pupillary movements, indicating that the "multiple meaning theory" may have to be modified.

Adult↗
PubMed1986

A verbal long term memory deficit in frontal lobe damaged patients.

The retention performance for learned words was compared in two groups of cortically damaged patients: A group of 14 patients with uni- or bilateral damage to the frontal lobes (group F), and a group of 14 patients with postrolandic damage. The patients learned three lists of words each of which had to be reproduced after 15 min. and after 1 day: one list under free recall, one under cued recall, and one under a recognition condition. While the performance of the two groups of patients was similar under all three conditions when tested after 15 min., group F was significantly inferior in the one day free recall retention test. We interpret this deficit as related in part to the classic "frontal" symptomatology (reduced attention and lack of initiative, drive, and concentration), and in part to a distinct disturbance of long term memory. We base this conclusion on the similar performance levels of frontal and non-frontal patients under all other conditions of testing, in particular under the free recall condition after the 15 min. delay. Reasons are given why attentive and drive related components might be mediated by prefrontal cortical neurons themselves, while mnemonic components might be mediated by mediodorsal thalamic neurons projecting to the prefrontal cortex. No or only minor differences could be established between the side of damage or between uni- versus bilateral frontal damage.

Adult↗
PubMed1986

The influence of glucocorticoid dose on protein catabolism after renal transplantation.

Protein catabolic rate (PCR) and protein balance were measured daily by computerized mass balance studies in 20 subjects during hospitalization after renal transplantation. All hospital courses were uncomplicated. Ten subjects received approximately 1 mg/kg/day prednisone, and ten subjects received 3-5 mg/kg/day prednisone on day 1 with a tapering dose to approximately 1 mg/kg/day by discharge. In both groups, PCR rose during the first 3-4 postoperative days then stabilized at an accelerated level. PCR was significantly greater in the higher prednisone group. Despite encouragement most subjects ate less protein than prescribed, and most were in negative protein balance. Mean daily and net protein deficits were more severe in the higher prednisone group. Higher protein intakes improved protein balance. The protein catabolic effects of the two regimens have been defined and a dose dependency demonstrated. In any therapeutic situation the use of the minimum effective dose of steroids seem advised, and high protein intake should be encouraged to improve protein balance. Some steroid morbidity might thus be avoided.

Adolescent↗
PubMed1985

Protein catabolism during the postoperative course after renal transplantation.

Protein catabolic rate (PCR) was measured daily by computerized mass balance studies in 50 subjects during hospitalization after renal transplant. All subjects received 60 mg prednisone per day. PCR rose over the first 3 to 4 postoperative days and then stabilized at an accelerated level, which was sustained through the third posttransplant week. Rejection therapy with either 3 mg/kg/d prednisone or 15 mg/kg/d of methylprednisolone for 3 days further increased PCR, but there was no difference in PCR between these two regimens. Protein restriction did not decrease PCR and subjects offered a higher protein diet did not have further acceleration of PCR. We conclude that 60 mg/kg/d prednisone produces an obligatory acceleration of PCR that is further accentuated by higher steroid doses. The use of minimal maintenance doses of prednisone consistent with adequate immunosuppression seems wise. Protein balance may be improved if protein intake is increased to match individual rates of accelerated protein catabolism.

Adolescent↗
PubMed1985

Altered patterns of posttransplant urinary tract infections associated with perioperative antibiotics and curtailed catheterization.

Postoperative urinary tract infections (UTIs) in renal transplant patients were studied before and after introduction of a protocol requiring single-dose perioperative antibiotics and earlier catheter removal. The overall incidence of UTIs was reduced from 55.4% to 26%. The most dramatic reduction was in nondiabetic males, from 56% to 8.2%. There was a small but statistically insignificant reduction in infection rates in females. There was no change in the rate of infection in diabetics. The incidences of noncoliform and mixed infections, in the group as a whole, were dramatically reduced from 42.9% to 12%, but Escherichia coli infections were totally unaffected. This protocol exposed the special susceptibility of women and diabetics to posttransplant UTIs and the different pathogenesis of E coli versus noncoliform infections. These features need more study.

Anti-Bacterial Agents↗
PubMed1984

Induction of insulin resistance in normal adipose tissue by uremic human serum.

An incubation of uremic human serum with normal rat adipose tissue will make the subsequently isolated adipocytes less responsive to insulin. To examine the extent of insulin resistance, we obtained sera from nondiabetic, uremic patients, who had not undergone dialysis therapy. The sera were then dialyzed (3500 molecular-weight cutoff) for 18 hr against a defined culture medium to eliminate possible in vitro effects of altered levels of end-product metabolites, electrolytes, and metabolic substrates. After an incubation of epididymal fat tissue from normal rats, for 3 hr with the dialyzed sera (50% vol/vol), cells were isolated and washed. The insulin stimulation of 14C-glucose (0.2 mM) incorporation to 14CO2 and total lipids was significantly reduced in the adipocytes pretreated with sera from 19 of the 29 uremic patients. Although elevated in the uremic patients, the sera levels of insulin, and parathyroid and growth hormones were not correlated to insulin resistant activity. Furthermore, incubation of adipose tissue for 3 hr with insulin, glucagon, or PTH did not produce resistance. The uremic sera reduced glucose utilization equally at 0.2 and 50 mM glucose, suggesting that the insulin resistance was induced additionally at a site distal to the glucose transport system. However, the concentration of insulin (22 microunits/ml) required for half-maximal stimulation of glucose metabolism was not altered by pretreatment with uremic serum. Also, neither the isoproterenol-stimulated lipolysis nor the inhibition of this cellular event was influenced by pretreatment with uremic sera.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1983

Age and prior caffeine use alter the cardiovascular and adrenomedullary responses to oral caffeine.

The effects of age and chronic caffeine use (approximately 300 mg/day) on the cardiovascular and humoral responses to 250 mg of oral caffeine (the equivalent of 2 to 3 cups of coffee) were examined. Older subjects had greater increases in blood pressure than younger subjects (p less than 0.03), and caffeine nonusers had greater blood pressure increases than caffeine users, regardless of age (p less than 0.05). Caffeine increased the product of systolic blood pressure and heart rate (an estimate of myocardial oxygen demand) in older caffeine nonusers, but this effect was absent in older caffeine users (p less than 0.01). Cardiovascular effects of caffeine could not be related temporally to changes in plasma epinephrine, which were greater in caffeine nonusers and younger subjects, or to plasma norepinephrine, renin activity or vasopressin, which did not change. Thus, age accentuates and moderate prior caffeine use attenuates the cardiovascular effects of oral caffeine; these effects are not mediated solely through the sympathoadrenal system.

Adrenal Medulla↗
PubMed1983

Renal threshold phosphate concentration in patients with idiopathic nephrolithiasis: correlations with tubular functions, serum parathyroid hormone and 1,25(OH)2D3.

The renal handling of inorganic phosphate was measured in 17 idiopathic nephrolithiasis patients with normal glomerular filtration rate and effective renal plasma flow. TmPO4/GFR was less than 2.5 mg/dl in nine subjects (Group I) and greater than or equal to 2.5 in eight (Group II). The former had serum PO4 of 2.5 +/- 0.13 mg/dl and the latter, 3.5 +/- 0.11 mg/dl (p less than 0.01). Four in Group I and five in Group II were hypercalciuric. There was no significant difference in the serum parathyroid hormone and 1,25(OH)2D3 between the two groups. However, renal tubular functions were abnormal in both groups. The low TmPO4/GFR in 53 per cent of the patients is another manifestation of tubular functional abnormality seen in idiopathic nephrolithiasis.

Adult↗
PubMed1983

Parathyroid hormone in patients with diabetes mellitus and end-stage renal disease on chronic haemodialysis.

Serum immunoreactive parathyroid hormone in patients with juvenile-onset diabetes mellitus and end-stage renal failure on chronic haemodialysis treatment is significantly lower than the values obtained from patients with adult-onset diabetes mellitus and non-diabetic patients with end-stage renal disease being similarly dialysed. The major determinants of parathyroid hormone secretion, such as calcium and magnesium, do not seem to be the factors responsible for this difference. The histology of the parathyroid glands in juvenile-onset patients shows fibrosis and collagen infiltration which reduce the functional mass of the glands.

Adult↗
PubMed1981

Renal transplantation in systemic lupus erythematosus.

3 patients with chronic renal failure due to lupus nephritis received kidney allografts from cadaver donors. Serological activity was present in 2 patients at the time of transplantation, and continued unabated despite intensive immunosuppressive therapy. Their allograft failed at 5 and 7 months after transplantation. Anti-DNA antibody in the allograft was found in 1 patient. The 3rd patient, with no serological activity at the time of transplantation, remained serologically negative, and her allograft functioned for 18 months. The persistence of serological activity in 1 patient, and the recovery of anti-DNA antibody from her allograft provide proof for the recurrence of lupus nephritis in the allograft.

Adult↗