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Biomedical subjects

P Downs

Publications and source records attributed to P Downs.

18 recordsLinked to original sources
PubMed1997

The acoustic properties of capsaicin-induced cough in healthy subjects.

Acoustic analysis of cough both in the time and frequency domain has been reported using voluntary and spontaneous cough. The main aim of this study was to discover whether such analysis of capsaicin-induced cough enables differences between normal subjects to be recognized. We present data from 13 healthy subjects (with normal lung function and no history of respiratory disease) using a new method of acoustic analysis, which presents the data in three graphical forms: 1) spectrogram; 2) overall spectral energy, 3) root mean square (RMS) pressure plots. Using the RMS sound pressure traces, different subjects had either two peaks, a single peak or multiple peaks. The occurrence of single and multiple peaks has previously been associated with disease states but we found them in normal subjects. The number of peaks and the visual pattern of the spectrogram was reproducible within and specific to each individual over time. During a peal of coughs in a single expiration, the peak amplitude of successive coughs decreased as lung volume reduced. Despite similarities in the overall spectral energy between individuals, there were marked differences in the small visual details of the spectrograms. However, in an individual, these small details were remarkably constant both within and between days, and can be regarded as a "cough signature". This type of spectrographic analysis provides a new approach to the analysis both of normal and abnormal cough sounds, and has identified similarities and differences in capsaicin-induced cough in normal individuals. It has potential as a tool with which to study the pathophysiology of cough.

Acoustics↗
PubMed1994

Intrageneric amplification of horse microsatellite markers with emphasis on the Przewalski's horse (E. przewalskii).

Primer sequences flanking 13 microsatellite loci isolated from the domestic horse (E. caballus) were successfully used to amplify homologous loci in the Przewalski's horse (E. przewalskii). The results demonstrate that the level of polymorphism at all 13 loci in the Przewalski's horse was comparable to that in the domestic horse and the overall exclusion probability in the Przewalski's horse was calculated to be 0.9994. The results suggest that it should be possible to use E. caballus-derived microsatellite markers to provide parentage verification and additional valuable information to the captive management of E. przewalskii. The ability to amplify corresponding loci in the remaining five species of the genus was also confirmed, illustrating the general application of markers isolated from the domestic horse to the evaluation of polymorphism in the other six species of the genus.

Animals↗
PubMed1987

"Health care is sick in St. Louis.".

The crumbling of the nation's public health care system is nowhere better illustrated than in St. Louis, Mo., where the city administration recently removed its ailing municipal hospital and clinics from public control in one quick, autocratic stroke. Helping the mayor "rescue" St. Louis "out of the health care business" were the city's business elite and the highly paid managers of National Medical Enterprises, one of the nation's largest for-profit health care corporations. The St. Louis story is just one local chapter of an unfolding tragedy which finds the poor and uninsured increasingly shut out and shunted aside as the nation's public and voluntary health sectors fall prey to what is euphemistically called "privatization."

Contract Services↗
PubMed1985

Control of intraabdominal hemorrhage and shock: a comparison of fluid resuscitation, MAST, and balloon occlusion.

Our study examined the efficacy of four treatment modalities in controlling hemorrhage and achieving hemodynamic stabilization in hemorrhagic shock: intravenous fluid replacement (IV); military antishock trousers used concomitantly with fluids (MAST); balloon occlusion at the level of the diaphragm with concomitant fluid replacement (balloon); and a combination of MAST inflation, balloon occlusion, and fluid resuscitation (MAST and balloon). Twenty-eight mongrel dogs were anesthetized, and the spleen was exposed and completely crushed. The abdomen was closed, and treatment was initiated and continued for four hours or until the dog died. For all conditions the hematocrit dropped during the course of the experiment; balloon occlusion was effective at slowing this drop (P less than .0001), but MAST had no statistically significant effect. Animals with balloons bled more slowly into the abdominal cavity than did animals in the other two groups (P less than .0001). MAST also were effective at slowing the bleeding (P less than .05). Of the balloon and the MAST and balloon dogs, all except one survived the entire four hours; this difference between balloon and nonballoon dogs is significant (P = .002). MAST did not have a statistically significant effect on survival. Perfusion pressure (PP) declined during the course of the experiment, and the balloon was effective at slowing this decline (P less than .0001); none of the other comparisons was statistically significant.

Analysis of Variance↗
PubMed1984

Laryngoscopic endotracheal intubation of rats for inhalation anesthesia.

Endotracheal intubation of the rat under direct vision is described together with the details of procedures and apparatus for conducting inhalation anesthesia in this species. Our intubation method requires no special manufacture of equipment, because it employs the human laryngoscope equipped with an infant blade (size 0). Using inhalation anesthetics such as enflurane or halothane for induction, clear laryngoscopic visualization of the glottis is reliably obtained, allowing rapid and routine intubation of the rat in a highly predictable amount of time. In contrast, the injected anesthetics such as ketamine or pentobarbital sodium seem unsuited to laryngoscopic intubation as a result of problems of variable induction times, copious oral secretions, and strong pharyngeal-laryngeal reflexes.

Anesthesia, Inhalation↗
PubMed1983

Venous return in hemorrhagic shock after application of military anti-shock trousers.

UNLABELLED: The effect of Military Anti-Shock Trousers (MAST) on inferior vena cava blood flow was studied during graded hypovolemia using a pump reservoir system and an in-line electromagnetic flowprobe. During hemorrhagic shock MAST inflation increased cardiac output 25.4% ( CONTROL: 0.92 +/- 0.09 l/min) and arterial pressure 50% ( CONTROL: 60 +/- 2 mmHg). The so-called "autotransfusion" effect due to blood displacement from the lower part of the body into the central circulation was found to be only 4.3 +/- 0.6 ml/kg, a volume much less than previously estimated in the literature. We conclude that MAST inflation reliably improves cardiac output and systemic blood pressure above the diaphragm in dogs subjected to hemorrhagic shock. This effect is mainly due to a diversion of the cardiac output to the upper half of the body due to impedance of flow to the abdomen and lower extremities, rather than to a significant volume shift constituting an autotransfusion of blood from the lower part of the body.

Animals↗
PubMed1982

Proteolytic enzyme levels during cardiopulmonary bypass.

Pulmonary damage resembling "shock lung" is frequently seen following cardiopulmonary bypass. In many of these cases a rise in the plasma level of proteolytic enzymes has been observed. In order to establish whether changes in plasma proteinase activity occur as a result of cardiopulmonary bypass per se, or whether hemodilution and surgical tissue destruction may be responsible, three groups of animals were studied. Control dogs were anesthetized, heparinized, and transfused rapidly with Ringer's lactate to a hematocrit of less than 30%. In the second group hemodilution was combined with a sham thoracotomy. The third group was perfused for 90 minutes on total cardiopulmonary bypass at flow rates between 60 and 95 ml/kg/min using a roller pump and an infant bubble oxygenator. Serum beta-glucuronidase and acid phosphatase activity was measured by spectrophotometry immediately after anesthesia and at fixed time intervals during the experimental procedure, as well as on the second and third postoperative days. It was found that beta-glucuronidase increased 78.2 +/- 6.6% during extracorporeal circulation, while acid phosphatase rose 46.3 +/- 4.2%. Increases in enzyme activity were significantly greater in the perfused group when compared with the sham-operated and the control groups. The results suggest that the postperfusion lung syndrome may be attributable in part to proteinase release caused by blood/material interaction within the extracorporeal circuit.

Acid Phosphatase↗
PubMed1981

MAST augmentation of external cardiac compression: role of changing intrapleural pressure.

Ventricular fibrillation was induced in nine dogs weighing 18 to 22 kg. CPR was performed with a mechanical chest compressor. Mean carotid flow during CPR was 7.9 +/- 1.5 ml/min. After MAST inflation to 100 mm Hg, the flow increased to 15.7 +/- 3.7 ml/min. Intrathoracic aortic systolic pressure was also significantly increased from 65 +/- 7 to 73 +/- 8 mm Hg. When the thorax was vented with chest tubes bilaterally, no change in carotid flow or arterial pressure was noted on closing or opening the chest tubes. One liver laceration and two gallbladder contusions were noted at autopsy. MAST inflation apparently augments carotid flow an systolic pressure. Variations in intrapleural pressure do not seem to have a significant influence on CPR.

Animals↗
PubMed1973

Control of thyroid hormone secretion in normal subjects receiving iodides.

The administration of exogenous iodides (saturated solution of potassium iodide, SSKI) to normal male volunteers resulted in a significant decrease in the serum concentration of thyroxine (T(4)) and triiodothyronine (T(3)) and a significant increase in serum concentration of thyrotropin (TSH). During the control period (phase I), serum concentrations of T(4) averaged 6.9+/-1.8 mug/100 ml (mean +/-SD), T(3) 106+/-15 ng/100 ml, and TSH 3.7+/-1.3 muU/ml. During the administration of 1 drop of SSKI twice daily for 11 days (phase II), there was a small but significant decrease in the serum concentration of T(4) and T(3) (5.8+/-1.6 mug/100 ml and 91+/-19 ng/100 ml, respectively) and a small but significant increase in the serum concentration of TSH (6.0+/-3.5 muU/ml). During the administration of 5 drops of SSKI twice daily (phase III) over the following 12-19 days, these changes persisted, except for a small increase in the serum concentration of T(3) (97+/-20 ng/100 ml), which was statistically significant when compared to values obtained during phase II. Values returned to control levels 14 days after withdrawal of SSKI. Almost all these observed changes took place within the limits of the normal range. It is postulated that, in euthyroid individuals, iodides specifically inhibit release of T(4) and probably of T(3). The resulting slight decrease in values for serum T(4) and T(3) elicits a small increase in TSH secretion which, it is postulated, antagonizes the inhibition of hormone release induced by iodides. As a result, a new equilibrium is reached which maintains the euthyroid state.

Adult↗
PubMed1973

Effects of replacement doses of sodium L-thyroxine on the peripheral metabolism of thyroxine and triiodothyronine in man.

Studies of the effect of L-thyroxine administration (0.3 mg daily for 7-9 wk) on the peripheral metabolism of (131)I-labeled triiodothyronine (T(3)) and (125)I-labeled thyroxine (T(4)) and on the concentration and binding of T(4) and T(3) in serum were carried out in 11 euthyroid female subjects. Administration of L-thyroxine led to consistent increases in serum T(3) concentration (137 vs. 197 ng/100 ml), T(3) distribution space (39.3 vs. 51.7 liters), T(3) clearance rate (22.9 vs. 30.6 liters/day) and absolute T(3) disposal rate (30 vs. 58 mug/day), but no change in apparent fractional turnover rate (60.3 vs. 60.6%/day). The proportion and absolute concentration of free T(3) also increased during L-thyroxine administration. Increases in serum total T(4) concentration (7.3 vs. 12.8 mug/100 ml) and in both the proportion and absolute concentration of free thyroxine also occurred. In five of the subjects, the kinetics of peripheral T(4) turnover were simultaneously determined and a consistent increase in fractional turnover rate (9.7 vs. 14.2%/day), clearance rate (0.84 vs. 1.37 liters/day), and absolute disposal rate (64.2 vs. 185.0 mug/day) occurred during L-thyroxine administration. Despite these increases in the serum concentration and daily disposal rate of both T(4) and T(3), the patients were not clinically thyrotoxic. However, basal metabolic rate (BMR) values were marginally elevated and, as in frank thyrotoxicosis, T(4)-binding capacities of thyroxine-binding globulin (TBG) and thyroxine-binding prealbumin (TBPA) reduced, suggesting that subclinical thyrotoxicosis was present. Thus, the often recommended replacement dose of 0.3 mg L-thyroxine daily may be greater than that required to achieve the euthyroid state. The studies have also provided additional evidence of the peripheral conversion of T(4) to T(3) in man and have permitted the calculation that approximately one-third of exogenously administered T(4) underwent deiodination to form T(3). To the extent that a similar fractional conversion occurs in the normal state, it can be calculated that a major fraction of the T(3) in serum derives from the peripheral deiodination of T(4) and that only a lesser fraction derives from direct secretion by the thyroid gland.

Adult↗