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Biomedical subjects

M L Clark

Publications and source records attributed to M L Clark.

209 records · Page 12Linked to original sources
PubMedDate not supplied

Evaluation of butaclamol in chronic schizophrenic patients.

In a double-blind, placebo-controlled study, an attempt was made to evaluate butaclamol in chronic schizophrenic patients using chlorpromazine (CPZ) as the standard comparative drug. With doses up to 50 mg/day, butaclamol was shown to have significant antipsychotic activity comparable to CPZ but with a much higher incidence of extrapyramidal signs. A more reasonable maintenance dose may be in the range of 5 to 20 mg/day. Rebound insomnia was noted again with butaclamol, which warrants further study.

Adult↗
PubMedDate not supplied

Breathing pattern of neonates during nonnutritive sucking.

Alteration of the breathing pattern seen during oral feeding has been attributed to the behavioral activity of sucking, repeated swallowing, and laryngeal chemoreceptor stimulation. Because it preserves the behavioral activity of sucking but eliminates the laryngeal chemoreceptor stimulation and repeated swallowing that occurs during nutritive sucking, the effects of nonnutritive sucking was evaluated in 19 term infants. The suck-pause pattern seen during nonnutritive sucking is similar to that of nutritive sucking. None of the variables measured (inspiratory duration, expiratory duration, breathing frequency, and tidal volume) were significantly altered during the overall period of nonnutritive sucking when compared with previously obtained control values. These results suggest that the alteration of breathing pattern observed during oral feeding cannot be accounted for by the behavioral activity of sucking per se. However, when the sucking phases of the nonnutritive period were compared with the intervening pauses, a reduction in the expiratory duration (P less than 0.05) and a reduction in tidal volume (P less than 0.05) were observed. Thus, the breathing pattern of human neonates is indeed altered during the sucking phase of the nonnutritive period; pressure changes associated with sucking may account for this alteration.

Humans↗
PubMedDate not supplied

The deposition of hygroscopic phosphoric acid aerosols in ciliated airways of man.

The hygroscopic growth of phosphoric acid aerosol (Dc greater than 0.5 micron) within the human tracheobronchial tree is modeled to investigate changes in deposition characteristics when compared to nonhygroscopic aerosols of identical preinspired size. Phosphoric acid particles are assumed to grow in a stepwise fashion to 99% relative humidity (RH) within conducting airways of the lung, having initially reached equilibrium at 90% RH (T = 37 degrees C) in the trachea. Deposition efficiencies for growth and no growth are calculated from theoretical equations for inertial impaction, sedimentation and diffusion. The results show that neglecting the growth of an inhaled phosphoric acid aerosol may result in underestimation of the total deliverable dose by a factor of as much as 600-700%. Significant differences in regional deposition sites for hygroscopic or nonhygroscopic aerosols are predicted. Increased deposition efficiencies imply that measured physical properties (respirable fraction, aerodynamic diameter) of aerosols alone are not sufficient to assess deposition characteristics within the lung; hygroscopic growth must also be considered.

Aerosols↗
PubMedDate not supplied

Use of a peptide rather than free amino acid nitrogen source in chemically defined "elemental" diets.

Previous studies have shown that amino acid (AA) residues are absorbed more rapidly from di- tripeptides than from free AA. In the present study, an intestinal perfusion technique has been used in normal human subjects to compare absorption of AA residues and total alpha-amino nitrogen (N) from 4 partial enzymic hydrolysates of protein (50--80% of the N contents present as small peptides) and their respective equimolar free AA mixtures. alpha-Amino N absorption was greater from 2 casein hydrolytes and a lactalbumin hydrolysate than from the respective free AA mixtures but similar to that from a fish protein hydrolysate and its AA mixture. The considerable variation in absorption of individual AA residues from the AA mixtures was much reduced when the protein hydrolysates were perfused, as a number of AA which were poorly absorbed from the AA mixtures were absorbed to a greater extent from the protein hydrolysates. The casein and lactalbumin hydrolysates had a stimulatory effect on jejunal absorption of water and electrolytes. In contrast, the fish protein hydrolysate appeared to cause a mean net secretion of fluid and electrolytes. The findings indicate that when absorption is limited by diminished luminal hydrolysis or absorptive capacity, serious consideration might be given to using partial enzymic hydrolysates of whole protein rather than free AA mixtures as the N source in "elemental" diets. Care should be taken, however, in ensuring that the preparation of choice does not promote a net secretion of fluid and electrolytes for such a property could have a deleterious effect in the clinical setting.

Adult↗