Efficacy of laparoscopic surgery for loop colostomy: a propensity-score-matched analysis.

PURPOSE: Colostomy is a common procedure for fecal diversion, but the optimal colostomy approach is unclear in terms of surgical outcomes and stoma-related complications. The purpose of this study was to examine the efficacy and feasibility of laparoscopic loop colostomy. METHODS: This retrospective cohort study included patients who underwent loop colostomy at Shizuoka Cancer Center in Japan between April 2010 and March 2022. Patients were divided into two groups based on surgical approach: the laparoscopic (LAP) and open (OPEN) groups. Surgical outcomes and the incidences of stoma-related complications such as stomal prolapse (SP), parastomal hernia (PSH), and skin disorders (SD) were compared with and without propensity score matching. RESULTS: Of the 388 eligible patients, 180 (46%) were in the LAP group and 208 (54%) were in the OPEN group. The male-to-female ratio was 5.5:4.5 in the Lap group and was 5.3:4.7 in the OPEN group, respectively. The median age was 68 years (range, 31-88 years) in the LAP group and 65 years (range, 23-93 years) in the OPEN group, respectively. The LAP group, compared with the OPEN group, had a shorter operative time and lower incidences of surgical site infection (3.9% versus 16.3%, respectively; p < 0.01) and SD (11.7% versus 24.5%, respectively; p < 0.01). There was no significant difference between the LAP and OPEN groups in the incidence of SP (17.3% versus 17.3%, respectively) or PSH (8.9% versus 6.7%, respectively). After propensity score matching, the incidences of surgical site infection and SD were significantly lower in the LAP group than in the OPEN group, while there were no significant differences in the operative time or the incidences of SP and PSH. CONCLUSION: Our results suggest that laparoscopic surgery could be beneficial and feasible in loop colostomy.

The influence of electrolytes in the adsorption kinetics of reactive BF-5G blue dye on bone char: a mass transfer model.

The discharge of harmful dyes in water bodies is a serious pollution problem, dangerous for the ecosystem's equilibrium and human health. In this sense, the aim of this work was to determine the influence of electrolytes (NaCl, KCl, CaCl2 and MgCl2) in the adsorption of Reactive Blue BF-5G dye, the most common dye used in industrial process for fabric colouring, using bovine bone char as the adsorbent. The bovine bone char was characterized by pH of point of zero charge (pHPZC), N2 adsorption-desorption isotherms, Fourier transform-infrared spectroscopy (FT-IR) and X-ray diffractometry (XDR). The characterization revealed a mesoporous structure (pore mean diameter of 94 Šand SBET ∼107 m2 g-1) with negative charge distribution at the surface (pHPZC = 3.8). The adsorption experiments revealed that the presence of KCl enhanced the material adsorption capacity (qmax = 195 mg g-1), that the Sips isotherm best fitted the experimental data (R2 > 0.9 except for KCl solution) and the adsorption process was mono- and multilayered. The kinetic adsorption experiments indicated that the inorganic electrolytes increased the initial adsorption velocity and the data was best modelled by the surface diffusional model (SDM), implying a resistance (aqueous > CaCl2 > NaCl > MgCl2 > KCl) to mass transfer at the surface of the pores which, in turn, prevented the dye diffusion to the interior of the adsorbent (qe = 71 mg g-1). Therefore, small quantities of KCl can be used to lower the mass transfer resistance and provide higher adsorption capacity with reduced time of operation, thus increasing the overall process efficiency.

Surgical starting time in the morning versus the afternoon: propensity score matched analysis of operative outcomes following laparoscopic colectomy for colorectal cancer.

BACKGROUND: The number of colorectal cancer cases is increasing, and so the number of laparoscopic colectomy procedures being performed is also increasing, leading to an increased workload for surgeons. However, operating for prolonged time periods may cause surgeons to lose their concentration and develop fatigue. We hypothesized that there is a time-of-day variation in outcome for patients with colorectal cancer who undergo laparoscopic colectomy. The present study aimed to compare the operative outcome between laparoscopic colectomy for colorectal cancer performed in the morning versus the afternoon. METHODS: This was a single-center, retrospective study. All 1961 consecutive patients who underwent laparoscopic surgery for colorectal cancer between 2007 and 2017 were included; 1006 of these patients underwent morning surgery, while 955 underwent afternoon surgery. These patients were analyzed using propensity score matching, giving 791 patients in each group. The short- and long-term outcomes in both groups were compared. RESULTS: Before propensity score matching, the morning group had a larger mean tumor size than the afternoon group (30 cm vs 35 cm; P = 0.0035). After matching, the two groups did not significantly differ in any patient characteristics. Compared with the afternoon group, the morning group had a significantly lesser incidence of intra-operative organ injury (0.25% vs 1.13%; P = 0.027), and a significantly greater incidence of post-operative abdominal abscess (2.03% vs 0.75% P = 0.028). The incidences of other complications and morbidities were similar in both groups. The median operative time in the morning group (201 min) was significantly longer than that in the afternoon group (193 min; P = 0.0124). The two groups did not differ in 5-year overall survival rates and 5-year disease-free rates within any disease stage. CONCLUSIONS: Surgical start times are correlated with surgical outcomes. Our data will help to ensure the safest possible surgeries.

Experimental study of inflammatory response and collagen morphometry with different types of meshes.

PURPOSE: To compare an inflammation score and collagen morphometry after incisional hernia repair with four different meshes at two time points. METHODS: Four types of mesh were used to repair an abdominal wall incisional defect in Wistar rats: high-density polypropylene (HW/PP); low-density polypropylene (LW/PP); polypropylene mesh encapsulated with polydioxanone coated with oxidized cellulose (PP/CE); and expanded polytetrafluoroethylene (ePTFE). An inflammation score based on histological analysis and collagen morphometry was performed after 7 and 28 days after operation (POD). RESULTS: Compared to LW/PP group at 7 POD, HW/PP group had lower (p = 0.014) and PP/CE group had higher inflammation scores (p = 0.001). At 28 POD, higher scores were seen in all the other groups compared to the LW/PP group (HW/PP, p = 0.046; PP/CE, p < 0.001; ePTFE, p = 0.027). Comparing groups individually at 7 and 28 PODs, all demonstrated lower inflammation score values at 28 POD (HW/PP, p < 0.001; LW/PP, p < 0.001; PP/CE, p = 0.002; ePTFE, p = 0.001). At 7 POD, higher amounts of collagen were detected in ePTFE compared to HW/PP (p < 0.001) and LW/PP (p = 0.004) and in PPCE group compared to HW/PP (p = 0.022). At 28 POD, no statistically significant difference was found. Comparing groups individually at 7 and 28 PODs, HW/PP and LW/PP showed larger amounts of collagen at the 28th POD, without any statistically significant differences for the PP/CE and ePTFE groups. CONCLUSIONS: Inflammation scores decreased in all groups at 28 POD. Collagen deposition was higher for non-composite meshes at 28 POD.

Age-dependent decrease in desflurane concentration for maintaining bispectral index below 50.

BACKGROUND: We examined the hypothesis that the minimum alveolar concentration of desflurane for maintaining bispectral index (BIS) below 50 (MACBIS 50 ) decreases with advance of age. METHODS: Sixty young (20-30 year), middle-aged (31-65 year) and elderly (66-80 year) patients were included (n = 20, each group). Five minutes following the start of continuous intravenous administration of remifentanil at 0.25 µg/kg/min, general anaesthesia was induced with propofol 2 mg/kg and rocuronium 0.8 mg/kg to facilitate tracheal intubation. Infusion of remifentanil was stopped immediately after tracheal intubation. When BIS began to increase > 60, maintenance of anaesthesia was started with an end-tidal desflurane concentration of 4.0% and maintained for 10 min followed by 1-min assessment of BIS taken at 10-s intervals. MACBIS 50 of each age group was estimated by up-down methodology. RESULTS: MACBIS 50 of desflurane in young, middle-aged and elderly patients was 4.25% end-tidal (95% confidence intervals 4.04-4.46), 3.58% (3.38-3.79) and 2.75% (2.50-3.00) respectively. MACBIS 50 was higher (P = 0.011) in young patients and lower (P = 0.012) in elderly patients than those in middle-aged patients. CONCLUSIONS: Advance in age significantly decreased the concentrations of desflurane required to maintain BIS below 50. BIS reflected age-associated decrease in end-tidal concentrations of desflurane required for maintaining adequate depth of anaesthesia during resting state.

Transnasal endoscopic approach in medial blow out orbit fractures

Objective: The purprose of this study is to present the team experience and the method efficacy in transnasal endoscopic approach of medial orbital blow out fracture using septum graft. Method: This approach was used in 14 patients with an isolated medial orbital wall fracture between June 2005 and June 2006. A computed tomographic scan was taken before and after surgery. The ocular motility and enophthalmos were checked before and after surgery. The endoscopic transnasal approach provided the appropriete surgical exposure in all cases. Patients were followed up for a mean of 8,2 months (range, 5-14 months) after repairing the orbital wall fracture. Hertel exophthalmometry was performed in all patients. Results: Hertel exophthalmometry showed that among 14 patients: 13 patients showed no enophthalmos. The enophthalmos ranged from 0.5-1 mm in 12 patients and 1.5 mm enphthalmos was noted in 2 patients. A clinically significant enophthalmos =2mm was not found postoperatively. Preoperatively, 2 (15%) patients had a diplopia in the primary position of the gaze and 12 (75%) patients had a diplopia within 30º of the gaze. Postoperatively, all patients had an orthotropia in the primary position but 1(7%) patient had a residual diplopia. Conclusion: The transnasal endoscopic approach using septal graft provides a minimally invasive, effective, and cosmetically pleasing surgical approach for managing an isolated medial wall fracture.

Chronic salt loading and cardiovascular-associated changes in experimental diabetes in rats.

1. High-sodium intake may increase blood pressure and diabetes is a salt-sensitive condition. In the present study, we evaluated cardiovascular changes and their neurohumoral mechanisms in streptozotocin (STZ)-diabetic rats that underwent chronic salt loading. 2. We studied male Wistar rats (150-280 g) 14 days after the injection of either STZ (50 mg/kg, i.v.; D; n = 18) or citrate buffer (C; n = 16). After the induction of diabetes, animals were maintained for 14 days with free access to standard rat chow and tap water (C and D groups) or 1% NaCl solution (C-S and D-S groups). We conducted two experiments. Experiment 1 consisted of basal arterial pressure (AP) measurement (30 min) followed by the evaluation of AP responsiveness to phenylephrine and sodium nitroprusside. One day later, with the rats anaesthetized, a blood sample was collected to test for glycaemia, plasma angiotensin-converting enzyme (ACE) activity and renin. Kidneys were removed for the determination of tissue ACE activity. Experiment 2 comprised 24 h urine collection followed by 3 days of cardiovascular records, which consisted of a 30 min basal AP measurement, followed by injection of blockers of the vasopressin system, the renin-angiotensin system (RAS) and the sympathetic system. Basal haemodynamic data, baroreflex evaluation and AP responses to blockade of the vasopressin system with vasopressin V(1) receptor antagonist (aAVP; 10 mg/kg, i.v.), the RAS by losartan (10 mg/kg, i.v.) and the sympathetic system by hexamethonium (20 mg/kg, i.v.) were determined. 3. Glycaemia was similar between C and C-S (P = 0.612) and between D and D-S (P = 0.552), but higher in diabetic compared with non-diabetic rats (P < 0.0001). The D-S rats had an increment of 24% in mean AP compared with D (120 +/- 4 vs 97 +/- 2 mmHg, respectively; P = 0.0001), which was not seen in C-S compared with C rats. A positive association was noted between urinary sodium and mean AP (r = 0.37; P = 0.04). Plasma renin was undetectable in D-S rats. The response to acute drug blockade of vasopressin and the RAS was similar among groups, but hexamethonium elicited a more pronounced decrease in AP in D-S compared with D rats (P = 0.001). 4. The main neurohumoral mechanisms of salt-induced cardiovascular changes in STZ-diabetes are increased sodium and vascular sensitivity to adrenergic stimuli, which act in combination to produce a final result of higher AP levels, a finding not observed in control rats. Baroreflex derangements induced by diabetes were not affected by salt overload.

Relationship between cardiovascular dysfunction and hyperglycemia in streptozotocin-induced diabetes in rats

Streptozotocin (STZ)-induced diabetes in rats is characterized by cardiovascular dysfunction beginning 5 days after STZ injection, which may reflect functional or structural autonomic nervous system damage. We investigated cardiovascular and autonomic function, in rats weighing 166 ± 4 g, 5-7, 14, 30, 45, and 90 days after STZ injection (N = 24, 33, 27, 14, and 13, respectively). Arterial pressure (AP), mean AP (MAP) variability (standard deviation of the mean of MAP, SDMMAP), heart rate (HR), HR variability (standard deviation of the normal pulse intervals, SDNN), and root mean square of successive difference of pulse intervals (RMSSD) were measured. STZ induced increased glycemia in diabetic rats vs control rats. Diabetes reduced resting HR from 363 ± 12 to 332 ± 5 bpm (P < 0.05) 5 to 7 days after STZ and reduced MAP from 121 ± 2 to 104 ± 5 mmHg (P = 0.007) 14 days after STZ. HR and MAP variability were lower in diabetic vs control rats 30-45 days after STZ injection (RMSSD decreased from 5.6 ± 0.9 to 3.4 ± 0.4 ms, P = 0.04 and SDMMAP from 6.6 ± 0.6 to 4.2 ± 0.6 mmHg, P = 0.005). Glycemia was negatively correlated with resting AP and HR (r = -0.41 and -0.40, P < 0.001) and with SDNN and SDMMAP indices (r = -0.34 and -0.49, P < 0.01). Even though STZ-diabetic rats presented bradycardia and hypotension early in the course of diabetes, their autonomic function was reduced only 30-45 days after STZ injection and these changes were negatively correlated with plasma glucose, suggesting a metabolic origin.

Relationship between cardiovascular dysfunction and hyperglycemia in streptozotocin-induced diabetes in rats.

Streptozotocin (STZ)-induced diabetes in rats is characterized by cardiovascular dysfunction beginning 5 days after STZ injection, which may reflect functional or structural autonomic nervous system damage. We investigated cardiovascular and autonomic function, in rats weighing 166 +/- 4 g, 5-7, 14, 30, 45, and 90 days after STZ injection (N = 24, 33, 27, 14, and 13, respectively). Arterial pressure (AP), mean AP (MAP) variability (standard deviation of the mean of MAP, SDMMAP), heart rate (HR), HR variability (standard deviation of the normal pulse intervals, SDNN), and root mean square of successive difference of pulse intervals (RMSSD) were measured. STZ induced increased glycemia in diabetic rats vs control rats. Diabetes reduced resting HR from 363 +/- 12 to 332 +/- 5 bpm (P < 0.05) 5 to 7 days after STZ and reduced MAP from 121 +/- 2 to 104 +/- 5 mmHg (P = 0.007) 14 days after STZ. HR and MAP variability were lower in diabetic vs control rats 30-45 days after STZ injection (RMSSD decreased from 5.6 +/- 0.9 to 3.4 +/- 0.4 ms, P = 0.04 and SDMMAP from 6.6 +/- 0.6 to 4.2 +/- 0.6 mmHg, P = 0.005). Glycemia was negatively correlated with resting AP and HR (r = -0.41 and -0.40, P < 0.001) and with SDNN and SDMMAP indices (r = -0.34 and -0.49, P < 0.01). Even though STZ-diabetic rats presented bradycardia and hypotension early in the course of diabetes, their autonomic function was reduced only 30-45 days after STZ injection and these changes were negatively correlated with plasma glucose, suggesting a metabolic origin.

Cardiovascular control in experimental diabetes.

Several studies have reported impairment in cardiovascular function and control in diabetes. The studies cited in this review were carried out from a few days up to 3 months after streptozotocin administration and were concerned with the control of the circulation. We observed that early changes (5 days) in blood pressure control by different peripheral receptors were maintained for several months. Moreover, the impairment of reflex responses observed after baroreceptor and chemoreceptor stimulation was probably related to changes in the efferent limb of the reflex arc (sympathetic and parasympathetic), but changes also in the central nervous system could not be excluded. Changes in renal sympathetic nerve activity during volume expansion were blunted in streptozotocin-treated rats, indicating an adaptive natriuretic and diuretic response in the diabetic state. The improvement of diabetic cardiovascular dysfunction induced by exercise training seems to be related to changes in the autonomic nervous system. Complementary studies about the complex interaction between circulation control systems are clearly needed to adequately address the management of pathophysiological changes associated with diabetes.

Cardiovascular control in experimental diabetes

Several studies have reported impairment in cardiovascular function and control in diabetes. The studies cited in this review were carried out from a few days up to 3 months after streptozotocin administration and were concerned with the control of the circulation. We observed that early changes (5 days) in blood pressure control by different peripheral receptors were maintained for several months. Moreover, the impairment of reflex responses observed after baroreceptor and chemoreceptor stimulation was probably related to changes in the efferent limb of the reflex arc (sympathetic and parasympathetic), but changes also in the central nervous system could not be excluded. Changes in renal sympathetic nerve activity during volume expansion were blunted in streptozotocin-treated rats, indicating an adaptive natriuretic and diuretic response in the diabetic state. The improvement of diabetic cardiovascular dysfunction induced by exercise training seems to be related to changes in the autonomic nervous system. Complementary studies about the complex interaction between circulation control systems are clearly needed to adequately address the management of pathophysiological changes associated with diabetes

Quantitative assessment of cranial defect healing and correlation with the expression of TGF-beta.

Circular parietal defects from 3 to 12 mm in diameter were made in 45 6-month old skeletally mature guinea pigs, and animals were sacrificed after survival periods of 3 days to 12 weeks. The original defect was harvested in continuity with a rim of surrounding bone and the adjacent dura and pericranium. After 12 weeks, all 3 and 5 mm defects were completely covered by a bridge of bone, while residual defects were noted within the 8 and 12 mm wounds. Percentage of new bone formation was significantly higher within 3 mm defects, than in all larger defects at each time interval from 1 week on (P < .05), reaching a mean of 93% in 3 mm defects and remaining below a mean of 31% in the remaining defect sizes. Immunolocalization demonstrated an osteogenic front in which the osteoblasts stained strongly for all isoforms of TGF-beta, with the intensity decreasing after the majority of the defects had reossified; this front was located at the advancing bone edge of the defect as well as the endocranial side adjacent to the dura. In conclusion, isoforms of TGF-beta are upregulated during a limited "window" of time corresponding to the period of calvarial reossification, and are localized to osteoblasts within an osteogenic front at the periphery and dural surfaces of the defects.

Osteogenesis in cranial defects: reassessment of the concept of critical size and the expression of TGF-beta isoforms.

Transforming growth factor-betas (TGF-beta) have been demontstrated to be upregulated during osteoblast function in vitro and during cranial suture fusion in vivo. The authors hypothesized that spontaneous reossification of calvarial defects was also associated with upregulation of TGF-beta. The present study was designed to (1) evaluate the concept of a critical-size defect within the calvaria in an adult guinea pig model and (2) investigate the association between the ossification of calvarial defects and TGF-beta upregulation. Paired circular parietal defects with diameters of 3 and 5 mm and single parietal defects with diameters of 8 or 12 mm were made in 45 six-month-old skeletally mature guinea pigs. Three animals per defect size were killed after survival periods of 3 days, 1 week, 4 weeks, 8 weeks, or 12 weeks. New bone ingrowth was evaluated by assessing for linear closure by a traditional linear method and by a modified cross-sectional area method using an image analysis system in which the thickness of new bone was taken into account. Immunohistochemistry was performed using rabbit polyclonal antibodies to localize TGF-beta1, -beta2, and -beta3. All specimens were photographed, and the intensity of immunostaining was graded based on subjective photographic assessment by three independent reviewers. No defect demonstrated any measurable bone replacement after a survival period of 3 days. All 3- and 5-mm defects were completely reossified after 12 weeks based on the linear analysis of new bone, indicating these defects to be less than critical size. However, new bone formation in the 5-mm defects never exceeded a mean of 40 percent by cross-sectional area of new bone. Percent of new bone formation by cross-sectional area was significantly higher within 3-mm defects than in all larger defects 4 weeks after the craniotomy, reaching a mean of 89 percent new bone by 12 weeks. Persistent gaps were noted on linear analysis of the 8- and 12-mm wounds by 12 weeks, and mean percent new bone by cross-sectional area remained below 30 percent. Immunolocalization demonstrated osteogenic fronts at the advancing bone edge and the endocranial side, in which the osteoblasts stained strongly for all isoforms of TGF-beta. The intensity of osteoblast expression waned considerably after the majority of the defect had reossified. These data indicate that histometric analysis based on cross-sectional area more accurately reflects the osteogenic potential of a cranial defect than does linear inspection of defect closure. Although the interpretation of immunolocalization studies is highly subjective, independent assessment by three reviewers indicates that isoforms of TGF-beta were upregulated during a limited "window" of time corresponding to the period of active calvarial reossification, and expression of TGF-beta corresponded to osteoblast activity within osteogenic fronts.

Reductive metabolism of stilbene oxide and styrene oxide to the olefins in rats.

The present study provides the first evidence that stilbene oxide and styrene oxide are reductively metabolized to the corresponding olefins in rats. When cis- or trans-stilbene oxide was given orally to rats, both cis- and trans-stilbene were isolated from the urine and feces. Styrene was also isolated from the urine and feces of rats given styrene oxide. These metabolites were identified unequivocally by UV and mass spectral comparison with authentic samples, and on the basis of their TLC and HPLC behavior. However, these olefins were not detected in the urine or feces of antibiotics-treated rats dosed with cis- or trans-stilbene oxide. Cecal contents of the untreated rats exhibited olefin oxide reductase activities toward cis- and trans-stilbene oxides under anaerobic conditions. The results suggest that intestinal bacteria play an important role in the reduction of olefin oxides to the corresponding olefins in the animal body.

Nitric oxide in the renal medulla protects from vasopressin-induced hypertension.

In the present study, we assessed whether activation of the nitric oxide (NO) system within the renal medulla could serve as a buffer against the chronic hypertensive effects of arginine vasopressin (AVP). NO concentration in the renal medulla of Sprague-Dawley rats was measured with in vivo microdialysis/oxyhemoglobin NO trapping. The results showed that medullary interstitial [NO] was increased after 2 hours of AVP infusion and remained elevated even after 10 days (by 62+/-8% and 42+/-13%, respectively). Western blot analysis showed that 2 days of AVP infusion was insufficient to increase protein expression of any of the NO synthase (NOS) isoforms, but after 10 days of AVP infusion, endothelial NOS expression was significantly increased in the inner medulla with no significant changes in noninducible NOS and inducible NOS levels. When renal medullary NOS enzyme activity was blunted with a nonpressor dose of N(G)-nitro-L-arginine methyl ester (75 microg. kg(-1). h(-1)) that was chronically infused locally into the renal medulla, intravenous AVP infusion (which was shown earlier to be subpressor in chronic studies) produced a sustained elevation in arterial pressure (from 107+/-2 to 121+/-2 mm Hg). These data indicate that chronic elevations in plasma AVP enhance renal medullary endothelial NOS protein expression, which enables sustained elevations of NO concentrations in this region of the kidney to buffer the hypertensive effects of AVP.

Increase in renal medullary nitric oxide synthase activity protects from norepinephrine-induced hypertension.

Studies were performed in conscious Sprague-Dawley rats to determine the role of the alpha(2)-adrenergic receptor-mediated increase in the renal medullary nitric oxide synthase (NOS) activity as a counterregulatory mechanism of blood pressure control in response to increased renal adrenergic stimulation. A subpressor dose of norepinephrine (NE, 8 microg. kg(-1). h(-1)) was infused intravenously, and NOS activity was determined with arginine-citrulline conversion by high-performance liquid chromatography in renal cortical and outer and inner medullary tissues. It was found that after 7 days of intravenous NE infusion, NOS activity was significantly higher in both the outer and inner medullary tissues (158+/-45 versus 30+/-24 pmol. mg(-1). h(-1) [outer medulla] and 5.1+/-0.7 versus 2.0+/-0.5 nmol. mg(-1). h(-1) [inner medulla] for NE-treated versus control rats, respectively). To determine whether the increase of NOS activity was mediated through renal medullary alpha(2)-receptors, the receptor antagonist rauwolscine (RAU, 1 microg. kg(-1). min(-1)) was infused via an implanted renal medullary interstitial catheter, and the consequences of intravenous NE administration were evaluated. NOS activity was significantly lower in the RAU-infused animals and did not increase with infusion of NE. To determine the systemic effects of the renal medullary alpha(2)-receptors, studies were performed to determine the consequences of chronic intravenous infusion of subpressor amounts of NE in the presence and absence of renal medullary alpha(2)-receptor inhibition. Under conditions in which RAU was continuously infused into the renal medulla, the same subpressor dose of NE caused sustained and reversible hypertension (mean arterial pressure increased from 120+/-3 to 131+/-3 mm Hg). Chronic blunting of the renal medullary NOS activity with N(G)-nitro-L-arginine methyl ester (75 microg. kg(-1). h(-1)) also enabled NE to produce a significant rise in mean arterial pressure (from 117+/-2 to 134+/-4 mm Hg). We conclude that the hypertensive effects of moderate elevations of renal adrenergic activity were chronically buffered by the alpha(2)-receptor-mediated increase in NOS activity within the renal medulla.

Utility of colorimetric end-tidal carbon dioxide detector for monitoring during prehospital cardiopulmonary resuscitation.

The purpose of this study was to evaluate a colorimetric end-tidal CO2 (ETCO2) detector (EASY CAP) as a monitor during prehospital cardiopulmonary resuscitation (CPR) without tracheal intubation. This detector was used for 121 patients during CPR with a laryngeal mask airway or face mask by authorized emergency lifesaving technicians. At 7 to 15 minutes after the initiation of CPR, ETCO was <0.5% in 30 cases (group A), 0.5% to 2.0% in 46 cases (group B) and >2.0% in 45 cases (group C). The rate of return of spontaneous circulation was 17% in group A, 24% in group B, and 48% in group C (groups A v C, P < .01). There was a significant difference in the rate of hospital admission between groups A and C. The ETCO2 value may be useful for monitoring during prehospital CPR with a laryngeal mask airway or face mask.

Local renal medullary L-NAME infusion enhances the effect of long-term angiotensin II treatment.

We hypothesized that the relatively high doses of angiotensin (Ang) II required to produce hypertension in rats were related to stimulation of renal medullary nitric oxide production, which in turn blunted reductions in medullary blood flow and the development of hypertension. Ang II was infused (5 days at 3 ng. kg-1. min-1 IV) to uninephrectomized Sprague-Dawley rats in the presence and absence of a continuous medullary interstitial NG-nitro-L-arginine methyl ester (L-NAME) infusion. Renal cortical and medullary blood flows were determined with the use of implanted optical fibers and laser-Doppler flowmetry. Ang II in the absence of medullary nitric oxide synthase inhibition did not change cortical or medullary blood flow or mean arterial pressure. A threshold dose of L-NAME was determined (75 microg. kg-1. h-1) that did not produce significant short- or long-term changes in medullary blood flow and mean arterial pressure. In rats with blunted medullary nitric oxide synthase activity, Ang II infused intravenously resulted in a 30% reduction in medullary blood flow (from 1.3 to 0.9+/-0.2V) and approximately 20 mm Hg increase in mean arterial pressure with Ang II infusion over 5 days. During 70 minutes after the start of intravenous Ang II, there was an immediate reduction in medullary blood flow, with no changes in cortical blood flow or mean arterial pressure. We conclude that the relative insensitivity of rats to long-term elevations of circulating Ang II is due to the potent counterregulatory actions of the nitric oxide system, specifically within the renal medulla. The results provide novel insights of how the organism attempts to protect itself from the hypertensive effects of Ang II.

Inducible nitric oxide synthase and blood pressure.

In the present studies, the influence of inducible nitric oxide synthase (NOS) inhibition with aminoguanidine on renal function and blood pressure was examined in rats. Intravenous aminoguanidine infusion (60 mg x kg-1 x hr-1) for 40 minutes to anesthetized Sprague-Dawley rats (n=7) resulted in no significant changes in mean arterial pressure or renal cortical blood flow, while medullary blood flow was slightly increased. Despite minimal effects on renal blood flow, urine flow was significantly decreased from 14.2+/-2.7 to 10.4+/-2.3 microL x min-1 x g kidney wt-1 during aminoguanidine infusion. To examine the possible effects of inducible NOS on blood pressure, aminoguanidine (10 mg x kg-1 x h-1 IV) was infused chronically into uninephrectomized rats maintained on a high salt (4.0% NaCl) diet. Mean arterial pressure significantly increased from 104+/-2 to 118+/-3 mm Hg after 6 days of aminoguanidine infusion (n=7) and returned to levels not different from those in the control group after 2 days of postcontrol infusion. Calcium-independent NOS activity in the renal medulla, a tissue that expresses inducible NOS in normal rats, was significantly decreased by 49% in the aminoguanidine-infused group (n=6) compared with that activity in the vehicle-infused control animals (n=6). In contrast, calcium-dependent NOS activity in the renal medulla was not significantly altered by aminoguanidine infusion, indicating specificity of aminoguanidine for inducible NOS in these experiments. In a final group of rats (n=5), oral L-arginine administration in drinking water (2% wt/vol) increased plasma arginine levels from 118+/-5 to 232+/-16 micromol/L and blocked the increase in arterial pressure after 6 days of aminoguanidine infusion. The present experiments provide evidence supporting a role for inducible NOS in the control of arterial pressure, possibly by renal tubular effects.

Time course of changes in heart rate and blood pressure variability in streptozotocin-induced diabetic rats treated with insulin

Autonomic neuropathy is a frequent complication of diabetes associated with higher morbidity and mortality in symptomatic patients, possibly because it affects autonomic regulation of the sinus node, reducing heart rate (HR) variability which predisposes to fatal arrhythmias. We evaluated the time course of arterial pressure and HR and indirectly of autonomic function (by evaluation of mean arterial pressure (MAP) variability) in rats (164.5 + 1.7 g) 7, 14, 30 and 120 days after streptozotocin (STZ) injection, treated with insulin, using measurements of arterial pressure, HR and MAP variability. HR variability was evaluated by the standard deviation of RR intervals (SDNN) and root mean square of successive difference of RR intervals (RMSSD). MAP variability was evaluated by the standard deviation of the mean of MAP and by 4 indices (P1, P2, P3 and MN) derived from the three-dimensional return map constructed by plotting MAPn x [(MAPn+1) - (MAPn)] x density. The indices represent the maximum concentration of points (P1), the longitudinal axis (P2), and the transversal axis (P3) and MN represents P1 x P2 x P3 x 10(-3), STZ induced increased urinary glucose in diabetic (D) rats compared to controls (C). Seven days after STZ, diabetes reduced resting HR from 380.6 + 12.9 to 319,2 + 19.8 bpm, increased HR variability, as demonstrated by increased SDNN, from 11.77 + 1.67 to 19.87 + 2.60 ms, did not change MAP, and reduced P1 from 61.0 + 5.3 to 51.5 + 1.8 arbitrary units (AU), P2 from 41.3 + 0.3 to 29.0 + 1.8 AU, and MN from 171.1. + 30.2 to 77.2 + 9.6 AU of MAP. These indices, as well as HR and MAP, were similar for D and C animals 14, 30 and 120 days after STZ. Seven-day rats showed a negative correlation of urinary glucose with resting HR (r=-0.76, P=0.03) as well as with the MN index (r=-0.83, P=0.01). We conclude that rats with short-term diabetes mellitus induced by STZ presented modified autonomic control of HR and MAP which was reversible. The metabolic control may influence the results, suggesting that insulin treatment and a better metabolic control in this model may modify arterial pressure, HR and MAP variability.