Biomedical subjects
Publications and source records attributed to J Harrison.
The aversion to daytime illumination in patients with congenital achromatopsia is not well understood. In the present study, we used a magnitude estimation procedure to compare the perceived brightness for 5 congenital achromats and for seven normal subjects. Contrary to the patients' beliefs, results suggest patients' brightness estimates are similar to those of normal subjects.
Type IIA von Willebrand's Disease (vWD) is the most common type II variant, and all reported cases (56 individuals in 26 families) have had autosomal dominant inheritance. An eight-year-old female with an increased bleeding tendency since infancy was found to have laboratory values typical of type IIA vWD, but her parents and siblings were asymptomatic. With the exception of uniformly decreased levels of ristocetin cofactor in relation to von Willebrand factor antigen, the results of family studies were normal including the presence of large multimeric forms of von Willebrand factor antigen. These findings are consistent with the propositus having the homozygous state of an autosomal recessive trait. Desmopressin infusion in the propositus was followed by a significant increase of factor VIII coagulant and von Willebrand factor antigen but a limited change in ristocetin cofactor with no development of large multimers.
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A long-latency (200-500 msec) endogenous potential with characteristics of the human P300 was recorded over 12 sessions in 4 adult cats. Principal components analysis with t tests showed that this potential was significantly larger in response to rare auditory stimuli than to the same stimuli presented frequently. The primary auditory cortex was ablated bilaterally. The preoperative tone-elicited conditioned eye blink response remained postoperatively. After 12 postoperative sessions, statistical analyses of these data demonstrated that the P300-like potential was still present. Thus, the primary auditory cortex is not necessary for generation of the P300-like response in cats.
Motor nerve conduction velocity was measured in six branches of the sciatic nerve in streptozotocin-diabetic rats. It was markedly reduced in nerves to the gastrocnemius, soleus, tibialis anterior, and extensor digitorum longus muscles. The branch to the plantaris muscle remained unaffected. In control rats none of these branches showed any evidence of conduction velocity maturation over the 2-month experimental period. Motor nerve conduction velocity to the interosseus muscles of the foot did show a normal maturation effect, which was halted by diabetes. We conclude that large-caliber motor fibers in mature nerves are particularly susceptible to diabetes.
Since Barrett's original description of the columnar lined lower oesophagus in 1950, this condition has been linked with over 140 cases of adenocarcinoma in the English literature. To date the youngest reported cases are a 23 year old male and a 25 year old male. This report concerns what is believed to be the youngest reported case of adenocarcinoma in a Barrett's oesophagus.
The rat monoclonal antibody NIM-R2 has been shown to be directed towards a cell surface differentiation antigen of murine B lymphocytes which is expressed to a greater or lesser extent at different phases of B-cell activation. In this report, NIM-R2 is shown to be capable of modulating the functional capacity of B cells. In the presence of the monoclonal antibody, the ability of fully mature antibody-forming cells to secrete their product is inhibited. This effect is, however, short-lived, with the cells quickly recovering secretory capacity, even in the continued presence of the monoclonal antibody. NIM-R2 also inhibits the generation of antibody-forming cells in culture, the addition of antibody as late as the third day of a 4-day culture period being effective in this respect. The evidence presented here suggests that these inhibitory effects of NIM-R2 are mediated through interference with separate mechanisms. Our data also indicate that, although NIM-R2 inhibits the generation of antibody-forming cells from their B-cell precursors, it does not affect the B-cell proliferative response. The findings are discussed in terms of their relevance to current models of B-cell activation and differentiation.
Infusion of prothrombin complex concentrates into pigs resulted in evidence of disseminated intravascular coagulation manifested by positive fibrin monomer tests, depletion of coagulation factors and platelets, and the presence of fibrin in small blood vessels at autopsy. All of the nine prothrombin complex concentrates were found to be thrombogenic. The response appeared to be dose-related, and the two activated materials were more thrombogenic than the non-activated products. In contrast, a purified factor IX concentrate resulted in minimal transient changes in only 2 of 5 animals tested, and autopsy findings were negative for fibrin deposition in all. Four of these animals received 200 factor IX units/kg, which was twice the dose used for any of the other products. Control animals received human plasma or albumin with no evidence of coagulation changes or fibrin deposition at autopsy. The porcine model is more sensitive than other animal models for detection of the thrombogenic effects of prothrombin complex concentrates and may be useful for testing new products found to be non-thrombogenic in other test procedures.
Long-latency endogenous responses with characteristics of the human P300 were recorded from young cats (1-3 years). Principal components analysis and paired t tests confirmed that responses within a 200-300 msec latency window were significantly larger to rate stimuli than to frequent stimuli. In contrast, a similar study of long-latency responses in old cats (more than 10 years) showed no significant difference between the 'rare' and 'frequent' responses. These data indicate that the P300 changes functionally with old age in the cat, as in the human, and that the cat provides an important model for P300 generator analysis in the aged as well as in the young brain.
Muramyl dipeptide, N-acetylmuramyl-L-alanine-D-isoglutamine (MDP), is the minimal biologically active subunit of bacterial peptidoglycan and elicits an acute inflammation in vivo. We now report that MDP is degraded by normal rat serum into its constituents, N-acetylmuramic acid and L-alanine-D- isoglutamine. The dipeptide is further degraded into its components L-alanine and D-isoglutamine. These results may help to explain how inflammation elicited by MDP is terminated in vivo.
Serum concentrations of fucose, sialic acid, and eight acute phase proteins were measured in single specimens from patients with cancer in order to determine whether the raised concentrations of protein bound sugars commonly found in cancer correlate with increased concentrations of the acute phase proteins. Strong positive correlations were found only with alpha 1-acid glycoprotein, alpha 1-antitrypsin, and haptoglobins. Changes in protein bound sugars and acute phase proteins were also examined in relation to patients' disease states. Serum fucose was raised more often in patients with advanced disease than in those in whom the spread of the tumour was more restricted; increased sialic acid concentrations, however, were found with a similar frequency in both these groups. Combined use of fucose and sialic acid values gave a high degree of marker positivity which could be only slightly improved on by including measurement of acute phase proteins. The combined use of serum fucose and sialic acid concentrations may have value in monitoring patients with cancer: the sialic acid provides an index of the acute phase response and the fucose a measure of the tumour spread.
Measurement of alpha-fetoprotein concentration and acetylcholinesterase activity in amniotic fluid can be used to identify chromosomal defects as well as neural tube defects. In seven cases of trisomy 21 and one case of partial trisomy 3, alpha-fetoprotein concentrations were below the reference range but values for acetylcholinesterase activity were normal for the appropriate gestational age. One case of trisomy 13 had an increase in acetylcholinesterase activity and normal alpha-fetoprotein concentration.
The calcium content of the central one third of the skeleton was measured using neutron activation analysis in 109 patients with idiopathic calcium nephrolithiasis. The bone mineral content (calcium bone index or CaBI, corrected for body size) was significantly decreased by 5.2% in 20- to 60-year-old patients with calcium nephrolithiasis (p less than 0.01). Under age 50 the decrease was more marked in 64 males (7.1%; p less than 0.02) than in 21 females (4.1%; p = NS). There was a significant negative correlation of CaBI with fasting urine calcium/creatinine ratio (r = 0.39; p less than 0.01), but no correlation with age or indices of parathyroid function. The decrease in bone mineral content did not appear to be progressive. The decrease in CaBI indicates negative calcium balance, either in the past or at present, in patients with calcium nephrolithiasis and does not favour increased intestinal absorption as a primary cause. The lack of correlation of CaBI with parameters of parathyroid function does not support a primary renal loss of calcium. The results suggest that increased bone turnover may be an important component of disordered calcium metabolism in patients with calcium nephrolithiasis.
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A new type II variant form of von Willebrand's disease has been recognized in a mother and daughter who have bleeding manifestations typical of von Willebrand's disease. Laboratory findings include consistently prolonged bleeding times, with normal levels of factor VIII procoagulant and antigen, but decreased ristocetin cofactor activity. Electrophoresis in SDS 1.5% agarose gel and reaction with 125I-labeled anti-factor VIII-related antigen rabbit IgG, followed by autoradiography, revealed that both plasma and platelets lack the large multimers of factor VIII-related antigen. In 2.5% gel, the propositus plasma lacked the normal "triplet" pattern. In 3.0% gel, a 5-band pattern was observed in normal, type IIA, and type IIB plasma, whereas type IIC plasma revealed a 2-band pattern. The patient's plasma revealed a 4-band pattern distinctly different from normal or other type II variants. We suggest that this new variant be labeled type IID, until a more appropriate nomenclature is developed.
Acquisition of a conditioned eyeblink reflex was studied in aged cats 10-23 years old and young cats one to three years old. All ten young cats became conditioned within 1,000 trials, after a mean of 270 trials, with a stimulus protocol including a 1500 msec 4 kHz tone CS+ followed by a shock unconditioned stimulus, and click CS-. Nine of 15 aged cats failed to become conditioned with 1,000 trials. Six old cats became conditioned after a mean of 522 trials. Four aged cats tested with a simpler protocol involving a 400 msec CS+ and no click CS- became conditioned with less than 500 trials. All retained the conditioned response when clicks were added to the 400 msec CS+. Three aged animals which failed to become conditioned with the 1500 msec CS+ and clicks were trained with an 800 msec CS+ without clicks. Only one became conditioned within 500 trials. Thus duration of the tone CS+ was critically important for acquisition of a conditioned eyeblink response by aged cats.