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Biomedical subjects

R B Freeman

Publications and source records attributed to R B Freeman.

At least 19 recordsLinked to original sources
PubMed1992

Memory search for faces and digits in patients with unilateral brain lesions.

To clarify whether the impairment of right-brain-damaged (RBD) patients in face recognition is related to perceptual or mnestic processing stages, we tested unilaterally lesioned patients and controls in a Sternberg-type memory search task. Subjects had to memorize sets of 1, 2, or 3 faces (or, in a control condition, digits) and were then to recognize these memorized stimuli among new ones by speeded choice reactions. In this task, deficits in stimulus encoding and memory search should show up in increased intercepts and slopes, respectively, of the RT function over memory set size. A face-specific impairment of the RBD patient group, consisting in longer reaction times and higher error rates, was confirmed but could not be unequivocally attributed to either stimulus encoding or memory search. However, inspection of individual data suggested that (1) some RBD patients are virtually unimpaired in face recognition and (2) if impairment after right hemisphere damage is present, it may selectively affect either stimulus encoding or memory search.

Adult↗
PubMed1992

Liver transplantation for primary hepatic cancer.

Although early survival following transplantation for primary hepatic cancer is excellent, previously reported high recurrence rates have generally discouraged liver replacement for this indication. Since the inception of the Boston Center for Liver Transplantation (BCLT) in 1983, 33 of 383 (8.6%) liver allograft recipients have undergone orthotopic transplantation as definitive treatment for otherwise unresectable cancer. Diagnoses included hepatocellular carcinoma (HCCA) in 24 patients (73%), and cholangiocarcinoma (CHCA) in 9 patients (27%). Actuarial survival rates for patients with hepatocellular carcinoma were 71%, 56%, and 42% at 1, 2, and 3 years, respectively. The actuarial survival rates for patients with cholangiocarcinoma were 89% at 6 months, and 56% at 1, 2, and 3 years. Of the nine patients with cholangiocarcinoma, 56% (5/9) developed recurrent disease. Although this recurrence rate is disheartening, because of the lack of other morbidity, long-term survival in these patients is comparable to patients with HCCA. In contrast, recurrent hepatocellular carcinoma developed in 25% of recipients (5/20) who survived longer than 3 months posttransplantation. Other causes of death in patients with hepatocellular carcinoma included perioperative complications, 16.6% (4/24); sepsis, 8.3% (2/24); coronary artery disease, 4.2% (1/24); and lymphoma, 4.2% (1/24). Favorable prognostic factors included: primary tumor less than 3 cm in size and absence of associated cirrhosis. These results emphasize that orthotopic liver transplantation can provide a long-term cure for approximately 50% of patients whose primary hepatic malignancy is unresectable by conventional procedures.

Adenoma, Bile Duct↗
PubMed1991

Sequential interleukin 2 and interleukin 2 receptor levels distinguish rejection from cyclosporine toxicity in liver allograft recipients.

Previous studies of renal transplant recipients have demonstrated that allograft rejection is accompanied by an increase in plasma and urinary levels of interleukin 2 and its soluble receptor before the development of clinical symptoms. After measuring interleukin 2 and interleukin 2 receptor levels in the plasma, bile, and urine of liver transplant recipients, we found that rejection is preceded by elevation of plasma and biliary levels of both substances, that cyclosporine toxicity did not affect either of these levels, and that urinary levels of the substances are unaffected in either condition. Levels of interleukin 2 and interleukin 2 receptors increased in bile earlier than in plasma, and interleukin 2 levels did not overlap among stable patients and those experiencing rejection, whereas levels of interleukin 2 receptors did. Serial measurements of interleukin 2 levels, particularly in the product of the transplanted organ, provide a reliable assessment of the immunologic status of the allograft.

Bile↗
PubMed1991

Serologic and DNA follow-up data from HBsAg-positive patients treated with orthotopic liver transplantation.

Fifteen hepatitis B surface antigen (HBsAg) positive patients treated with orthotopic liver transplantation were studied to determine whether any clinical, serologic, or histologic data were predictive for recurrent hepatitis B infection leading to graft failure. Six patients died early, one due to primary graft nonfunction and the remaining five due to septic complications. There were nine patients surviving longer than two months, eight of whom are alive at a mean follow-up of 556 days. HBsAg and hepatitis B core antibody (anti-HBc) reappeared in the sera of all survivors after a variable transient period of clearance. One patient died 3 months posttransplant of fungal sepsis and was found to have histologic evidence for recurrent hepatitis and positive immunoperoxidase staining postmortem. The remaining eight survivors are home and clinically well, with no histologic evidence of hepatitis. Seven of these eight patients have hepatitis B viral DNA in their sera. We conclude that while there is a high early mortality, usually from sepsis, none of the serologic, histologic, or DNA data analyzed can be used to predict graft loss from recurrent hepatitis. No grafts have been lost due to recurrent hepatitis B in this series, and therefore we believe that HBsAg positive patients should not be excluded from transplantation.

Adult↗
PubMed1991

Trends in kidney procurement and transplantation in New York State.

The growth in the number of Medicare patients with end stage renal disease (ESRD) in New York State receiving cadaver kidney transplants in the 1980s substantially lagged behind growth in the nation. Compared to the United States, New Yorkers on dialysis had less access to transplants. The greatest decline in transplant rates was experienced by New York's black population. During the early and mid-1980s, considerable transplant rate growth in New York City was maintained, despite very slow growth in local kidney procurement, by importing kidneys from other states, by residents seeking transplants elsewhere, and by a greater proportion of transplants going to Medicare ESRD patients. Since 1986, the number of kidneys procured in New York City increased while the number procured nationally fell. However, kidney imports to New York City dropped dramatically and thus the number of cadaver transplants declined despite the growth in local procurement. Upstate, procurement and transplants started at a higher level, but grew even more slowly.

Cross-Sectional Studies↗
PubMed1989

End-stage renal disease and the practice of nephrology.

Data from a national survey of 336 nephrologists who provide dialysis care on capitation reimbursement show differences in practice activity associated with the proportion of patients with end-stage renal disease (ESRD). On the average, ESRD patients account for 53% of patients seen by these physicians. Nephrologists who have the majority of their visits with ESRD patients average more than 120 patient encounters per week, approximating the practice workloads of primary care physicians. Nephrologists spend comparable amounts of time providing treatment for ESRD and non-ESRD patients in the same settings, schedule additional office visits for facility dialysis patients, and provide treatment and advice for problems not related to dialysis. Whereas care for acute renal failure patients is primarily based on consultations and involves a narrow focus, treatment for ESRD involves the provision of comprehensive primary medical care by nephrologists to their patients being treated with dialysis.

Ambulatory Care↗
PubMed1988

Surgical treatment of necrotizing enterocolitis: a population-based study in the Grampian region, Scotland.

Ninety-two cases of necrotizing enterocolitis (NEC) were diagnosed in the Grampian Region of Scotland between 1978 and 1984, for a regional incidence of 2.2/1,000 live births. Twenty-seven cases (29.3%) required surgery, 19 acutely and eight for delayed stricture. Acute operative mortality was 10.5%. Disease-related mortality was 3.3%, and overall mortality was 8.7%. Follow-up ranged from 15 to 77 months for surgical patients, with only three of 23 survivors having increased bowel frequency.

Enterocolitis, Pseudomembranous↗
PubMed1988

Case-mix and treatment in end-stage renal disease: hemodialysis v peritoneal dialysis.

The University of Southern California School of Medicine conducted a nationwide survey of 336 nephrologists to obtain demographic and clinical data on 6,411 patients with end-stage renal disease (ESRD). Patient demographic data, along with ESRD etiology and comorbid conditions noted by the physician, were compared across various modalities of dialysis. Characteristics of the treatment provided were differentiated by the mode of dialysis and the location of the patient encounter. Results of the analysis show that patients on peritoneal dialysis are more likely to be female and have higher rates of diabetes compared with hemodialysis (HD) patients. Statistically, patients on intermittent peritoneal dialysis are older, more likely to be black, and have a higher incidence of cardiovascular conditions. Continuous ambulatory peritoneal dialysis patients have greatest problem severity and require more physician time and more complex services, whereas home HD patients require the greatest number of diagnostic tests and therapeutic procedures. Hospital inpatient care shows greater case-mix severity and more intensive treatment, but this does not differ by the mode of dialysis. Finally, patients of freestanding dialysis facilities are more likely to have hypertensive renal disease, whereas patients at hospital-based facilities are older, more likely to be seen in the hospital, have more urgent and severe problems during dialysis rounds, and require more physician time, more complex services, and more diagnostic tests and therapeutic procedures.

Age Factors↗
PubMed1987

Renal tubular dysfunctions in patients with idiopathic calcium nephrolithiasis.

To define the degree of renal tubular involvement in idiopathic calcium nephrolithiasis, 18 patients (aged 23-60 years, 15 men and 3 women, with 1-30 years of renal stone history) with normal glomerular filtration rate (GFR) and effective renal plasma flow with no history of urinary tract infection and on no dietary or drug therapy underwent the following studies: measurement of proximal tubular maximum reabsorption of glucose (Tmglucose) and secretion of para-aminohippurate (TmPAH), urinary concentrating ability after 14 h of fluid deprivation, and urinary net acid excretion following an oral dose of ammonium chloride, 0.1 g/kg of body weight. Seventeen healthy subjects in the same age range served as control. Patients with calcium nephrolithiasis, with normal renal hemodynamic functions, have significantly lower proximal tubular maximum reabsorptive and secretory functions, diminished urinary concentrating mechanism, and reduced urinary net acid excretion following an oral acid load. These tubular functional abnormalities were observed in patients with or without hypercalciuria.

Adult↗
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↗