Biomedical subjects

C Cronin

Publications and source records attributed to C Cronin.

At least 37 records · Page 2Linked to original sources

PubMed1994

Correction of intramyocardial hypercarbic acidosis with sodium bicarbonate.

Although it has been hypothesized that exogenously administered bicarbonate can exacerbate intramyocardial acidosis and compromise contractile function, this phenomenon has not been demonstrated in an intact model in which intramyocardial pH (pH(int)), regional venous pCO2, and regional contractile function have been simultaneously monitored. In 20 anesthetized dogs, we studied the effects of intracoronary infusions of sodium bicarbonate NaHCO3 30 mEg over 15 min, on regional pH(int), (glass electrode) and regional stroke work (SW, sonomicrometry) before and after creating systemic hypercarbic acidosis by hypoventilation. During NaHCO3 administration, regional coronary venous pCO2 increased rapidly during the first minute (eucapnea; 34 +/- 7 to 55 +/- 18 mm Hg; hypercapnea: 70 +/- 15 to 98 +/- 23 mm Hg, P < 0.05 for both increases). Regional venous pH rose from 7.36 +/- .04 to 7.55 +/- .06 (P < 0.05) after the first minute of NaHCO3 infusion during eucapnea and from 7.09 +/- .09 to 7.22 +/- .09 (P < 0.05) during hypercapnea. During the first minute of NaHCO3 infusion, pH(int) declined minimally. However, during the remaining 14 min of each infusion, pH(int) increased significantly (eucapnea: 7.19 +/- 0.10 to 7.43 +/- 0.12; hypercapnea: 6.86 +/- 0.14 to 7.02 +/- 0.15, P < 0.05 for both changes). Regional SW decreased significantly during the first minute of infusion, both during eucapnea (23,400 +/- 7,400 to 18,000 +/- 6,300 ergs/cm2, P < 0.05) and hypercapnea (27,000 +/- 9,100 to 25,000 +/- 10,000 ergs/cm2, P < 0.05). The first minute of contractile dysfunction was followed by recovery and ultimately supranormal contractile function during the remainder of each bicarbonate infusion. To test the hypothesis that transient intracellular acidosis during bicarbonate infusions was underestimated by measurements of pH(int), measurements of intracellular pH using the pH-sensitive dye, BCECF, were performed in isolated guinea pig papillary muscles incubated in vitro. These measurements confirmed the presence of transient intracellular acidosis during bicarbonate infusion. In conclusion, (1) the intracoronary administration of sodium bicarbonate causes a transient depression in myocardial contractile function that is related to transient intracellular acidosis; and (2) despite exacerbating hypercarbia, sodium bicarbonate ultimately neutralizes intracellular acid and augments myocardial contractile function.

Acidosis↗

PubMed1993

Retrograde coronary sinus perfusion provides non-homogeneous myocardial blood flow.

The ability of retrograde cardioplegia to protect the right ventricle has been questioned. Canine myocardial circulation was assessed by infusing colored microspheres through the coronary sinus. The relative flow index (RFI), a normalized measure of tissue blood flow, was determined for 76 sections of myocardium. Three distinct flow regions were evident from these measurements. A paucity of blood flow through some basal sections of the right ventricle (RFI = 0.23 +/- 0.19) was found to be significantly different (p < 0.005) from regions of the heart with normal flow (RFI = 1.12 +/- 0.06). Sections from the right ventricular apex demonstrated augmented flow (RFI = 3.72 +/- 1.18). These data indicate that retrograde coronary perfusion provides nonuniform flow and under some conditions may provide inadequate perfusion to portions of the right ventricle.

Animals↗

PubMed1993

The effect of living abroad on alcohol expectancies among American adolescents in Germany.

Previous research has indicated that living abroad has a mitigating effect on alcohol use among American adolescents. Self-reported reasons for drinking and alcohol expectancies of American high school students who have lived abroad for 2 years or less were compared to those of American high school students who have lived abroad for over 10 years. Results indicated that students who have lived abroad for over 10 years endorse social and pleasure seeking and tension reduction reasons for drinking less often than students who have spent 2 years or less outside of the United States. Implications for preventive programs are discussed.

Adolescent↗

PubMed1993

Evolving colonoscopy skills in a rural family practice: the first 293 cases.

During the 1980s, many family physicians acquired flexible sigmoidoscopy skills for the early detection and secondary prevention of colorectal cancer. As these skills have matured, some family physicians have advanced from flexible sigmoidoscopy to the performance of colonoscopy. This is a descriptive report of this phenomenon from the private practice of one family physician. The first five years of total colonoscopy experience (293 procedures) were analyzed. No complications were encountered. A learning effect (measured in terms of scope depth and anatomical depth) was present during the first 50 procedures; an improvement in examination depth between the 25th and 50th procedure was present. Previous abdominal surgery had an effect on limiting scope-insertion depths. There were no complications, and among sedated patients, 137/253 (54%) of procedures reached the cecum. Important findings included cancer, polyps, and colitis. Twenty-seven percent (9/34) of important pathological findings were located beyond the reach of the 60 cm sigmoidoscope. This study of full colonoscopy in private family practice suggests it is safe, and the diagnostic yield is substantial. Additional studies by family physicians are needed regarding technique, quality assurance, and patient satisfaction.

Adolescent↗

PubMed1993

Esophagogastroduodenoscopy by family physicians phase II: a national multisite study of 2,500 procedures.

We have prospectively studied 1,783 upper gastrointestinal tract endoscopy procedures as performed by family physicians from thirteen separate office practices. Phase I of the study previously reported on 717 procedures in which patient management was enhanced, diagnostic yields were high, and biopsies were performed where appropriate. In Phase II, the data totaled 2,500 procedures representing 51.1 years of cumulative practice experience by the entire group. All cases were gathered prospectively and biopsies were confirmed by a pathologist's independent tissue analysis. In this series, family physicians were asked to record all complications, and to specify the exact manner in which performance of the procedure enhanced patient management. There have been biopsies in 1,230 (69% biopsy rate) Phase II cases with biopsy reports available in 1,194 (97% reporting rate) cases. There is pathological confirmation of the family physicians' visual diagnosis in 1,104 of 1,194 (93%) available biopsy reports for a 92% accuracy rate. There have been no complications, and the complication rate for the total series (1/2, 500) is now 0.0004.

Biopsy↗

PubMed1992

Calcific aortic stenosis and autonomic dysfunction.

With an aging population, calcific aortic stenosis is becoming more important in medical practice. Its cause is unknown. This paper hypothesises autonomic dysfunction is the abnormality underlying the tendency of the aging aortic valve to calcify, a proposition based on 2 main lines of evidence: 1. the similarity between aortic valvular calcification and medial arterial calcification, the latter a condition in whose pathogenesis autonomic dysfunction is implicated; 2. the similarity between the changes of autonomic denervation and those of natural aging in the aortic valve, of which calcific aortic stenosis is an exaggerated form. Autonomic denervation leads to withdrawal of neurotrophic influences from cells and tissues. The resulting changes in function and in structure, it is proposed, give rise to a condition of vulnerability allowing other stresses, such as haemodynamic trauma, to result in calcification.

Aged↗

PubMed1992

The use of nuclear magnetic resonance imaging in monitoring total body iron in hemodialysis patients with hemosiderosis treated with erythropoietin and phlebotomy.

Two hemodialysis patients with hemosiderosis were treated with combined erythropoietin and repeated phlebotomy. Serial nuclear magnetic resonance (NMR) imaging and serum ferritin levels were used to monitor the efficacy of treatment. This treatment modality has definite advantages over chronic deferoxamine therapy. NMR image-derived parameters offer an objective, accurate, and noninvasive indication of tissue iron stores.

Adult↗

PubMed1992

Recovery of intralipid from lumbar puncture after migration of saphenous vein catheter.

A term female infant was admitted to the intensive care unit with the diagnosis of tetralogy of Fallot with critical pulmonary stenosis. On the seventh day of life a long saphenous line was inserted that remained without complications until seven days later when the infant appeared septic. A lumbar puncture demonstrated the presence of intra-lipid in the cerebrospinal fluid that we interpreted as due to migration of the saphenous catheter. The child had an uneventful recovery.

Catheters, Indwelling↗

PubMed1992

Organized systems of care. A vision of a future healthcare delivery system.

Policymakers no longer question that healthcare system reform will occur; rather they differ on the timing and direction of change. The Washington Business Group on Health envisions a future healthcare delivery system called an organized system of care (OSC). An OSC is an integrated financing and delivery system that uses a panel of providers selected on the basis of quality and cost management criteria to furnish members with comprehensive healthcare services. The most important system attribute of the OSC will be the commitment of all involved to the mission of promoting the health of system members. To accomplish this mission, OSCs will incorporate the principles of continuous quality improvement. Care will be delivered through care management teams, which integrate the physical, psychological, and administrative needs of the member. Such teams might be made up of primary care physicians, nurses, and mental health professionals. Although the entire team would be responsible for the OSC member, one team member would be assigned primary responsibility for overseeing and planning care with the member.

Comprehensive Health Care↗

PubMed1990

Controlled-release morphine bioavailability (MS Contin tablets) in the presence and absence of food.

The bioavailability of a single, orally administered, 30-mg controlled-release morphine tablet (MS Contin Tablet; The Purdue Frederick Company, Norwalk, Conn.) was compared after fasting or a high fat meal in this single dose, randomized, crossover study involving 24 healthy male subjects. There was no significant (p greater than 0.05) difference in the mean extent of morphine absorption over 24 hours in the presence or absence of food (area under the plasma concentration vs. time curve [AUC(0,24)], fed = 107% of fasted). Time to maximal concentration (Tmax) was similar (p greater than 0.05) in the two treatment groups; the mean Tmax for fed volunteers was 2.5 hours versus 2.4 hours for fasted volunteers. The two regimens did not differ significantly (p greater than 0.05) with regard to maximal morphine concentration (Cmax); mean Cmax for fed subjects was 8.22 ng/ml whereas mean Cmax for fasted subjects was 8.53 ng/ It was concluded that consumption of a high fat meal did not affect either the rate or extent of morphine absorption, or any of the other pharmacokinetic parameters tested, following administration of MSC.

Administration, Oral↗

PubMed1990

The overnight dexamethasone test is a worthwhile screening procedure.

The overnight low-dose dexamethasone test is a convenient screening procedure for Cushing's syndrome. Claims that the test is associated with a high incidence of 'false positives', rendering it of little value particularly in obese and hospital in-patients, have been investigated in the present study. The data from 100 consecutive subjects undergoing overnight low-dose dexamethasone tests to examine for the possibility of Cushing's syndrome, were reviewed. Cushing's syndrome was identified in four patients, normal suppression of cortisol values occurred in 84 patients and 12 patients exhibited false positive results. Differences in body weights, body mass indices or in-patient status did not distinguish between those subjects with normal suppression of plasma cortisol and those subjects who yielded false positive results. These data indicate that the simple overnight dexamethasone test substituted for the more cumbersome traditional 48-h dexamethasone test in 84 of 96 patients who did not have Cushing's syndrome. Thus the overnight test provides a useful screening procedure but a small percentage of patients, approximately 12.5%, will require additional procedures to exclude Cushing's syndrome.

Adolescent↗

PubMed1990

Acute renal failure and non-Hodgkins lymphoma in a patient with minimal change glomerulonephritis.

Two rare features of minimal change glomerulonephritis occurring together in an adult patient are described. A 70-year-old man presented with acute renal failure and the nephrotic syndrome. Investigation revealed minimal change glomerulonephritis and non-Hodgkins lymphoma. Anti-lymphoma treatment reversed both the renal failure and the nephrotic syndrome. Minimal change glomerulonephritis, as a cause of acute renal failure and as a manifestation of malignancy, is briefly reviewed.

Acute Kidney Injury↗

PubMed1989