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Biomedical subjects

C Harvey

Publications and source records attributed to C Harvey.

At least 109 records · Page 6Linked to original sources
PubMed1982

Pituitary responses to a neuroactive tripeptide (TRH) in Friedreich's ataxia families.

Oral glucose tolerance, thyroid function tests, as well as thyrotropin, prolactin and growth hormone release after administration of thyrotropin releasing hormone, were evaluated in patients with Friedreich's ataxia and unaffected family members. Impaired glucose tolerance was found in the majority of family members, affected or not. Thyroid hormone levels and PRL and TSH responses to TRH, were similar in all and normal. However, GH responses to TRH were abnormal in half of the patients, but in none of the unaffected family members. Paradoxical responses to neuropeptides may characterize some Friedreich's ataxia patients, and may predict the possibility of therapeutic maneuvers with such peptides in these patients.

Adolescent↗
PubMed1980

Hypertrophic cardiomyopathy in Friedreich's ataxia: symmetric or asymmetric?

We evaluated 15 patients with Friedreich's ataxia (FA) to define the incidence of myocardial involvement and the type of cardiomyopathy observed. All patients with FA had either ECG, vectocardiographic or echocardiographic abnormalities, suggesting some degree of myocardial involvement. In contrast to reports indicating that asymmetric septal hypertrophy (ASH), often obstructive, is associated with FA, symmetric, concentric hypertrophic cardiomyopathy (SCH) was the predominant abnormality (sixty-seven percent of patients). Echocardiograms should be performed periodically in all FA patients since this technique allows the detection of cardiac hypertrophy.

Adolescent↗
PubMed1980

Friedreich's ataxia and oral glucose tolerance: I. The effect of ingested glucose on serum glucose and insulin values in homozygotes, obligate heterozygotes and potential carriers of the Friedreich's ataxia gene.

Glucose tolerance and insulin release were evaluated in 16 families with Friedrich's ataxia. Impaired glucose tolerance differed in incidence according to the method of evaluation, but was increased in number in parents and siblings of Friedreich's cases. Insulin output was not quantitatively different from normal, although the insulin peak was often delayed. This finding, in association with impaired glucose tolerance, suggest a defect in glucose entry into cells.

Adolescent↗
PubMed1980

Friedreich's ataxia and oral glucose tolerance: II. The effect of ingested glucose on serum growth hormone in homozygotes, obligate heterozygotes and potential carriers of the Friedreich's ataxia gene.

Homozygotes, obligatory heterozygotes and potential carriers of the Friedreich's Ataxia gene were tested with an oral glucose tolerance in order to assess a. the prevalence of abnormalities in glucose handling, b. the secretory pattern of two "diabetogenic" hormones, growth hormones and prolactin and c. to evaluate the possibility for detection of an abnormal trend in these hormones to be used as a genetic marker. Despite the high prevalence of glucose abnormalities horizontally and vertically in these families, the basal output and responses of these metabolic hormones to a glucose challenge were appropriate and thus not characteristic of any of the above groups.

Adolescent↗
PubMed1979

Immersion vs pressure-breathing and diaphragmatic function in the upright position.

In seven anesthetized dogs, immersion in the upright position to mid-neck level (IM) was compared to pressure breathing (PB) under dry conditions during constant-stimulus diaphragmatic contraction (EPS). The comparison was in terms of EPS-induced changes in alveolar pressure under static condition (Pmus); EPS-induced tidal volume (VT); and the VT/Pmus ratio (C'). It was found that at iso-lung volume (V): (a) Pmus was greater in IM than in PB, the difference increased at higher V; (b) VT was greater in IM than in PB, but the VT difference (deltaVT) did not parallel that in Pmus; VT was maximum at a V equal to approximately 90% of FRC in air (FRCd) and decreased below and above this volume; (c) during both IM and PB, the VT-V relationship reflected a biphasic relationship of C' to V and appeared to be inherent to the upright position.

Animals↗
PubMed1977

Thymosin alpha1: isolation and sequence analysis of an immunologically active thymic polypeptide.

The amino acid sequence of a biologically active polypeptide isolated from calf thymus, termed thymosin alpha1, has been determined. Thymosin alpha1 is a heat stable, highly acidic molecule composed of 28 amino acid residues. This peptide is one of several present in thymosin fraction 5 that may participate in the regulation, differentiation and function of thymus-dependent lymphocytes (T cells). A nomenclature for the family of polypeptides present in thymosin fraction 5 is suggested.

Amino Acid Sequence↗
PubMed1977

Human tecg changes during prolonged hyperbaric exposures breathing N2-O2 mixtures.

In an effort to determine whether hyperbaric exposures while breathing N2-O2 mixtures have an effect on cardiac depolarization and repolarization, electrocardiograms of 10 divers participating in four N2-O2 saturation dives were analyzed. In all cases, a decline in heart rate was observed upon compression to saturation depth (20-30%); a slow adaptation and return of heart rate toward normal was observed in those dives where the depth and environmental parameters remained constant. twhenever excursion dives were performed, the heart rate responded by decreasing on deeper excursions and increasing on upward excursions. Hyperbaric bradycardia disappeared after 8 days at pressure during the saturation dives at 50 and 60 feet seawater gauge (fswg), but was still present at this time at 200 fswg. The magnitude of the hyperbaric bradycardia produced by excursion dives following saturation at depth was influenced by the state of adaptation of heart rate. Decompression was uniformly accompanied by a rapid increase in heart rate resulting in a significant elevation in the postdive period. Alterations in myocardial repolarization as evidenced by Q-T interval, ST, and T wave changes were observed. Development of slight right ventricular conduction delay compatible with right ventricular strain was noted in four of the divers during the two deepest dives to 100 and 198 fswg. During the latter dive, progressive decrease in P wave amplitudes and eventual loss of P waves resulting in an apparent nodal rhythm was observed in one diver. Multiple premature ventricular contractions occurred in another diver. These observations, along with the reports by other authors, suggest that the different variables associated with the hyperbaric environment--gas density, pressure, inert gas--have a definite effect on the pacemaker activity of the heart and myocardial depolarization and repolarization.

Adaptation, Physiological↗
PubMed1975

Enzymatic multiplication of a chemically synthesized DNA fragment.

A synthetic DNA fragment of 19 residues was enlarged by the enzymatic addition of deoxyadenylate residues to its 3'-end with calf thymus terminal deoxynucleotidyl transferase. The 3'-terminus of this elongated DNA strand was blocked with 2', 3'-dideoxyadenylate to prevent hydrolysis by the 3'-exonuclease function of E. coli DNA polymerase I. This elongated and 3'-blocked fragment was annealed to an oligomeric primer and used as a template for the synthesis of a complementary copy of the synthetic 19-mer. The product of such a repair synthesis was separated by gel filtration and analyzed by nearest neighbor techniques. All template strands were copied with complete repair in over 90% of the chains. Facile recovery of the elongated template by virtue of its size permitted repetition of the copy process, thus allowing accumulation of the desired strand.

Animals↗
PubMed1975

Determination of the 3' terminal nucleotide of DNA fragments.

A new method for determining the 3'-terminal nucleotide of a DNA strand is presented. Use is made of the fact that one (and only one) 2',3'-dideoxyribonucleotide can be added to the 3'-end of a DNA fragment with calf thymus terminal transferase. Addition of more than one nucleotide analog per strand is impossible due to the absence of a 3'-terminal hydroxyl group. If the terminatind dideoxyribonucleotide contains an (alpha 32p) label, the resulting 3'-blocked strand can be digested by "nearest neighbor" techniques and the original 3'-endgroup determined. Picomole quantities of DNA strands can be labeled and the 3'-end determined.

Animals↗