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Biomedical subjects

R E Sosa

Publications and source records attributed to R E Sosa.

At least 19 recordsLinked to original sources
PubMed1996

Oliguria during laparoscopic surgery: evidence for direct renal parenchymal compression as an etiologic factor.

Abdominal insufflation during laparoscopy has been associated with transient oliguria, which abates after desufflation. Direct renal compression evoking a Page kidney effect was proposed as a mechanism. In an effort to confirm this theory, the left kidney was subjected to 15 mm Hg compression in six anesthetized mongrel dogs. For this, a pressure cuff was placed around the kidney excluding the renal hilar structures. The contralateral kidney was left untouched to serve as a control. After a steady-state period, the pressure cuff was inflated to 15 mm Hg for 2 hours. Cuff desufflation was followed by a 1-hour recovery period. Urine output, glomerular filtration rate (GFR), and effective renal blood flow (ERBF) were measured for both kidneys during each clearance period. For the treated kidneys, the mean urine output decreased 63% (P < 0.05) during compression and increased 109% (P < 0.05) after cuff desufflation. The GFR decreased 21% (P < 0.01) during compression and increased 25% (P < 0.05) during recovery. The ERBF decreased 26% (P < 0.05) during compression, and during the 1-hour recovery period, ERBF did not recover to baseline values. For the control kidneys, there were no significant changes in urine output or GFR during the experimental and recovery periods. These data support the view that direct renal parenchymal compression is an important factor in the development of insufflation-induced oliguria. The clinical implications of insufflation-induced oliguria during laparoscopy deserve further investigation.

Animals↗
PubMed1995

Laparoscopic laser-assisted bladder autoaugmentation.

OBJECTIVES: The purpose of this study is to examine the feasibility of performing a laparoscopic bladder autoaugmentation and to assess the urodynamic characteristics of an autoaugmented bladder. METHODS: Laparoscopic bladder autoaugmentation was performed in 9 female canines (20 to 30 kg). Following laparoscopic access to the peritoneal cavity, a midline bladder seromyotomy was performed using the potassium titanyl phosphate 532 nm laser. This produced a large bladder diverticulum. Changes in bladder volume and compliance were quantified over a 3-month period of follow-up. RESULTS: Urodynamic evaluation demonstrated an increase in bladder capacity 6 weeks postoperatively in 8 of 9 dogs, with an average volume increase of 45%. Bladder compliance improved in 7 of 9 dogs with an average increase in compliance of 67%. Three months postoperatively, bladder capacity remained increased in 5 of 9 dogs, with an average increase in volume of only 5.3%. An improvement in compliance was sustained in 5 of 9 animals with an average increase of 13.9%. Laparoscopic exploration revealed grossly normal bladders with adhesions of omentum to the seromyotomy site in all canines and the anterior abdominal wall in 2 of 9 canines. Histologically, the seromyotomy site was devoid of muscle with an intact urothelium and a proliferation of loose connective tissue. CONCLUSIONS: The technique of laparoscopic bladder autoaugmentation can be performed easily in the canine model. Although results at 6 weeks show significant improvement, the longer term, 3-month results were not statistically significant. This technique has the potential to offer a minimally invasive correction for patients with low-capacity, high-pressure bladders that have failed pharmacologic treatment.

Abdominal Muscles↗
PubMed1993

Chromophore enhanced laser welding of canine ureters in vitro using a human protein solder: a preliminary step for laparoscopic tissue welding.

Laser welding of the genitourinary tract has the potential advantage of forming an immediate watertight seal. It may obviate the need for sutures, eliminate the inherent lithogenic reaction to suture, and potentially improve healing. In the current study we employed a KTP-532 laser in vitro to weld canine ureters. Ureters were transected over a stent and immediately repaired using the KTP-532 laser (power density 7.14 W/cm.2, spot size = 0.5 cm.) alone or in combination with different tissue solders. Solders consisted of 40% human albumin alone or with the addition of iron oxide or fluorescein as light absorbing dyes (chromophores). Following the repairs, intraluminal bursting strength and the total energy required to complete the repairs were measured. The KTP laser alone was not able to achieve a satisfactory repair. Successful ureteral repairs were achieved in all solder groups while maintaining ureteral continuity at supraphysiologic pressures.

Anastomosis, Surgical↗
PubMed1993

Laparoscopy.

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Adrenal Gland Neoplasms↗
PubMed1992

Renal divalent cation excretion in secondary hypertension.

1. To determine whether abnormal renal calcium excretion is unique to primary genetic hypertension, blood pressure and 24 h urinary excretion of calcium, magnesium, sodium and creatinine were measured in deoxycorticosterone-saline and two-kidney, one-clip Goldblatt hypertensive rats and in their respective controls on low (0.2%) and high (1.8%) dietary calcium intakes. 2. Calcium supplementation lowered blood pressure (P < 0.05) in deoxycorticosterone-saline rats and in control saline-loaded rats, raised blood pressure in two-kidney, one clip rats, and had no effect in sham-operated control rats. 3. On both diets, calcium excretion was higher in hypertensive than in normotensive rats. The high calcium diet increased urinary calcium excretion in all rats, but the changes in urinary calcium excretion closely paralleled the diet-induced changes in blood pressure. Thus, urinary calcium excretion in deoxycorticosterone-saline animals, in whom calcium lowered blood pressure the most, rose the least (107%). Urinary calcium excretion rose the most in two-kidney, one-clip animals (1113%), whose blood pressure also rose the most. 4. Urinary magnesium excretion was also abnormal in hypertensive rats compared with normotensive rats, falling on the high compared with the low calcium diet in normotensive rats, but not in either hypertensive strain. Furthermore, urinary magnesium excretion was closely linked to urinary calcium excretion in saline-loaded control rats (r = 0.78; P = 0.008), but was dissociated from urinary calcium excretion in deoxycorticosterone-saline rats (r = 0.02; not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Laparoscopy: new applications of an established technique.

The safety and cost-effectiveness of any new procedure is, of course, brought into question in this era of heightened fiscal concerns. In general, a review of initial results with laparoscopic pelvic lymph node dissection appears to reveal sufficient patient benefits to warrant further work with these less invasive techniques. The principal benefits include the following: Decreased patient morbidity, early and latent; Shorter hospitalization; Faster recovery and return to normal daily functions; Equivalent efficacy to open surgical alternatives; Overall cost-effectiveness Cosmetic effect; minimizes loss of body image; Reproducible results. Perfecting the skills necessary for complicated laparoscopic surgery requires a commitment of time and work on the part of the surgeon. This is not a procedure that will be learned by auditing a few cases. Laparoscopic surgery requires diligence in mentally and physically preparing the skills needed for surgery and caution in the application of these skills. Nurses can help to minimize this learning curve by taking an active interest in the current and future practice of laparoscopic surgery and by sharing their knowledge and enthusiasm.

Education, Nursing, Continuing↗
PubMed1990

Relation of plasma renin to end organ damage and to protection of K+ feeding in stroke-prone hypertensive rats.

We studied the effects of regular diet (0.35% NaCl/1.1% potassium), high sodium diet (4% NaCl/0.75% potassium), or high sodium and high potassium diet (4% NaCl/2.11% potassium) on blood pressure, plasma renin activity, renal and cerebrovascular lesions, and incidence of stroke and mortality in male stroke-prone spontaneously hypertensive rats (SHRSP). In the first 4 weeks, the rise in blood pressure was higher in high NaCl than in high NaCl/high potassium or regular diet groups. However, by 8 and 12 weeks, the blood pressure in all three groups was similar. After 4 weeks of diet, plasma renin activity was similar in the three groups (3.4 +/- 0.8, 4.1 +/- 0.9, and 5.2 +/- 1.6 ng/ml/hr, in high NaCl, high NaCl/high potassium, and regular diet groups, respectively) and were not related to sodium excretion. After 8 weeks, plasma renin activity was significantly increased only in the high NaCl group (13.7 +/- 3.7 ng/ml/hr), and by 12 weeks plasma renin activity was significantly higher in the high NaCl group (25.3 +/- 3.6 ng/ml/hr) than in the high NaCl/high potassium (11.1 +/- 2.9 ng/ml/hr) or in the regular diet (7.8 +/- 4.6 ng/ml/hr) groups. Moderate to severe renal vascular lesions were first detected in the high NaCl group by 8 weeks of diet. At 12 weeks, renal vascular damage index (RVDI), estimated histologically, was significantly higher in the high NaCl group (RVDI = 79 +/- 14) than in the high NaCl/high potassium (RVDI = 40 +/- 11) and regular diet (RVDI = 7.8 +/- 4.6) groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Angiotensin II-induced atrial natriuretic factor release in dogs is not related to hemodynamic responses.

Angiotensin II (Ang II) and atrial natriuretic factor (ANF) appear to act as functional antagonists in the regulation of fluid and electrolyte homeostasis and blood pressure. To further define the relations between these hormones in vivo, we investigated the effect of low doses of Ang II (1-10 ng/kg/min) on plasma ANF levels. We also evaluated the influence of ANF release on the renal and hormonal responses to ANG II. Studies were performed in anesthetized and conscious instrumented dogs during sustained saline load and converting enzyme inhibition. In the anesthetized dogs, Ang II significantly increased plasma ANF levels and ANF arteriovenous difference without changing either atrial pressures or hematocrit. In both conscious and anesthetized dogs, ANF increases were not correlated with blood pressure responses to Ang II and did not occur in control groups when Ang II was replaced by vehicle. Ang II-induced sodium retention and stimulation of aldosterone production were attenuated, and renin suppression was enhanced in dogs having the largest changes in plasma ANF in response to converting enzyme inhibition or Ang II. These results demonstrate that in volume-replete dogs Ang II can promote ANF release independently of changes in atrial pressures or systemic hemodynamics, suggesting that Ang II may exert a significant modulatory effect on ANF secretion. The results also show significant relations between ANF and renal and adrenal responses to Ang II, which may suggest that, in turn, endogenous ANF modulates the effects of Ang II.

Adrenal Glands↗
PubMed1989

Laser welding of pedicled flap skin tubes.

The efficacy of the carbon dioxide laser used at high power levels for tissue destruction is well established. This laser at lower power levels has been used to incise and anastomose blood vessels, tendons, nerves, dura, bowel, fallopian tube, vasa deferentia, ureters and skin. Laser welding is faster, reduces surgical manipulation and introduces less foreign material into the wound than conventional suturing techniques. We tested the feasibility of laser welding of pedicled flap skin tubes to determine if there is a potential application in reconstruction, particularly for hypospadias repair.

Animals↗
PubMed1987

Intracellular pH in human and experimental hypertension.

31P NMR spectroscopy was utilized to evaluate intracellular pH in erythrocytes from normotensive (n = 15) and from untreated (n = 16) and treated (n = 24) human essential hypertensive individuals. Intracellular erythrocyte pH was also measured in normotensive rats on different dietary calcium intakes as well as in volume-dependent deoxycorticosterone/saline and renin-dependent, 2 kidney, 1 clip (2K-1C) Goldblatt hypertensive rat models. Untreated essential hypertensives had significantly lower intracellular pH values compared with normotensive subjects [7.17 +/- 0.02 vs. 7.28 +/- 0.02 (mean +/- SEM), significance level = 0.01]. Treated hypertensives had intracellular pH values indistinguishable from normotensives [7.27 +/- 0.02 (mean +/- SEM)]. Similarly, pH values for each rat model varied inversely with blood pressure, regardless of whether increased dietary calcium intake lowered pressure (normotensive and deoxycorticosterone/saline hypertensive rats) or elevated it (2K-1C Goldblatt hypertensive rats). These results demonstrate that lower intracellular pH values are commonly observed in various hypertensive states and suggest that they may contribute to the pathophysiology of the hypertensive process. Alterations in intracellular pH may also underlie the clinically observed linkage of hypertension with other disease syndromes, such as diabetes mellitus and obesity.

Animals↗
PubMed1986

Differing hemodynamic responses to atrial natriuretic factor in two models of hypertension.

Hemodynamic responses to synthetic atrial natriuretic factor (ANF), were studied in renin-dependent two-kidney, one-clip (2K,1C) and deoxycorticosterone (DOC) salt-treated hypertensive rats as well as normotensive controls. ANF infusion (800 pmol/kg prime, 120 pmol X kg-1 X min-1 for 60 min) decreased blood pressure (BP) more in conscious 2K,1C (-24 +/- 4%) than in DOC salt-treated (-12 +/- 4%, P less than 0.05) or control rats. Hemodynamic parameters were also evaluated during graded infusion of three doses, each for 30 min. At 24 and 120 pmol X kg-1 X min-1, ANF lowered BP in 2K,1C rats, both conscious (from 156 +/- 6 to 144 +/- 7, P less than 0.05 and 135 +/- 5 mmHg, P less than 0.05) and anesthetized (from 148 +/- 7 to 138 +/- 7, P less than 0.05 and 128 +/- 7, P less than 0.05). In anesthetized 2K,1C, BP changes were associated with reduction in total peripheral resistance (TPR) that became significant at 120 pmol X kg-1 X min-1 (-10 +/- 2%), whereas cardiac output (CO) and stroke volume (SV) were unchanged. In DOC-salt-treated rats these doses did not lower BP despite progressive falls in CO (-7 +/- 3% and -24 +/- 5%, P less than 0.05) and SV (-8 +/- 2% and -23 +/- 5%, P less than 0.05), which were balanced by a simultaneous rise in TPR (+12 +/- 4% and +26 +/- 10%, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Relationship between renal hemodynamic and natriuretic effects of atrial natriuretic factor.

The degree by which atrial natriuretic factor (ANF)-induced renal hemodynamic changes account for its natriuretic effect was determined by early clamp experiments in six anesthetized dogs. After control periods, perfusion pressure of the left kidney (LK) was reduced to 80-90 mmHg, and synthetic ANF (auriculin A) was infused intravenously (0.3 micrograms X min-1 X kg body wt). After recovery, furosemide (F) was administered as a bolus injection (1 mg/kg body wt). In the right kidney (RK), which served as a time control, ANF increased (P less than 0.05) glomerular filtration rate (GFR) 16 +/- 4% and Na excretion (UNa V) 261 +/- 63%, whereas it decreased urine osmolality (Uosm) 36 +/- 7% without changing free water clearance. ANF also increased diuresis (V) and kaliuresis (UKV). F produced qualitatively the same results without changing GFR. In the clamped LK, ANF failed to increase GFR (22 +/- 4 vs. 26 +/- 4 ml/min), UNaV (30 +/- 9 vs. 33 +/- 11 mueq/min), V, and UKV or to decrease Uosm (841 +/- 97 vs. 840 +/- 114 mosmol/kg H2O). F had similar effects in LK as in RK. The data demonstrate that the natriuretic effect of ANF is abolished when its renal hemodynamic actions are impeded. In addition, the results demonstrate that ANF antagonizes renal vasoconstriction in the dog. The results are consistent with the view that the ANF-induced natriuresis is due in great part to an increase in the filtered load of Na into a washed-out inner medulla.

Animals↗
PubMed1986

Effects of atrial natriuretic factor on blood pressure and the renin-angiotensin-aldosterone system.

Atrial natriuretic factor (ANF) antagonizes vasoconstriction induced by numerous smooth muscle agonists and also lowers blood pressure in intact animals. ANF has particularly marked relaxant effects on angiotensin II-contracted vessels in vitro. Sensitivity to the blood pressure-lowering effect of ANF in vivo appears to be enhanced in renin-dependent models of renovascular hypertension compared with other experimental hypertensive models. The depressor action of low, possibly physiological doses of ANF in two-kidney, one-clip Goldblatt rats is due to a decrease in total peripheral resistance. On the other hand, high doses of ANF can lower cardiac output, particularly in volume-expanded models such as deoxycorticosterone-salt hypertension. ANF markedly inhibits renin secretion in intact animals, probably via increased glomerular filtration rate and load of sodium chloride to the macula densa. This effect is masked when renal perfusion is impaired (e.g., via unilateral renal artery constriction), in which case ANF may stimulate renin secretion slightly. ANF also reduces plasma aldosterone in vivo and inhibits basal and agonist-induced aldosterone release from isolated adrenal cortical cells. This effect appears to be especially marked for angiotensin-induced aldosterone production in vivo and in vitro. These findings indicate that ANF has potentially important interactions with the renin-angiotensin-aldosterone system and suggest a role for ANF in the homeostatic control of blood pressure as well as of extracellular fluid volume.

Adrenal Glands↗