Study of the upper pole after subtotal splenectomy in rats

PURPOSE

To evaluate macro/microscopic viability of the upper pole (UP) in rats after 80 days of subtotal splenectomy preserving the upper pole (SSPUP).

METHODS

Twenty-five male Wistar rats were submitted to SSPUP. After 80 days, the rats were euthanized, and the remaining UP was evaluated macroscopically regarding appearance, color, consistency, length, width, thickness, and presence of fibrosis/necrosis; and microscopically regarding presence of red and white pulp, fibrosis/necrosis.

RESULTS

Two rats died during surgery and were removed from the statistical analysis. There was statistically significant increase in length and width between the pre and postoperative in the experimental group, with no significant difference in thickness. In the manipulation group, the macroscopic appearance of the spleen was normal in pre and postoperative, with viability preserved. In the experimental group, two UP of the spleen were not found during the second surgery. Macroscopically, it was observed absence of fibrosis and necrosis in all cases. Microscopically, the white and red pulp were intact in both groups. Two spleens of rats in the manipulation group presented areas with fibrosis and necrosis focus, which were not enough to be considered inviable.

CONCLUSIONS

The UP of the spleen remained viable in 91.3% of the cases.

The influence of splenic tissue on the survival and TCD4 and TCD8 lymphocyte rates in rats subjected to fecal peritonitis induction

PURPOSE

Comparing survival rates of rats subjected to spleen procedures after fecal peritonitis induction. Assessing changes in TCD4 and CD8 lymphocyte rates before and after the procedures. Correlating animal survival with CD4 and CD8 lymphocytes.

METHODS

Thirty male Wistar rats were distributed into 3 groups of ten: spleen manipulation (SM); total splenectomy (TS); subtotal splenectomy with preservation of the inferior pole (IP). Rats were subjected to surgical procedure depending on the group. Seven days after surgery they underwent induction of peritonitis and survival time was recorded. All animals were subjected to two blood collections: before surgery and 70 days after it for TCD4/TCD8 lymphocyte counting.

RESULTS

Mean survival time was longer in the IP and SM groups and shorter in the TS group; there was significant difference between them. The comparison of the median number of CD4 did not present changes, whereas the comparison of the median number of CD8 decreased in the SM and IP groups. The correlation between the median number of TCD4 and TCD8 lymphocytes and the animals' survival was not significant.

CONCLUSION

The maintenance of splenic tissue contributed to increase the survival of rats and there was a change in the number of TCD8 lymphocytes.

Macro and microscopic comparison of the upper pole of the spleen with the lower pole in partial splenectomy

Purpose

To evaluate the viability of the upper (UP) and lower pole (LP) of the spleen from a macro and microscopic point of view, after subtotal splenectomy with preservation (SSP) of the UP and the LP.

Methods

Seventeen male Wistar rats, two months old, were submitted to SSPUP and SSPLP and 5 to simulated operation (SG). After 80 days, the rats were euthanized, and the remaining LP and UP and intact spleens were evaluated macroscopically and microscopically.

Results

Two rats died during the operation. Macroscopic analysis showed that in 15 LP, one of them was not viable and in 15 UP and in 5 spleens in the SG, all were viable. In the statistical analysis, there was no difference in relation to viability. The LP and UP analyzed showed variation. As for the length, the UP increased significantly; however, in relation to the width, there was a significant increase in the LP in relation to the UP. In addition, the weight of the UP was significantly greater than that of the LP. Microscopic analysis attested viability of the splenic remnants.

Conclusion

There was no significant difference regarding the viability of UP and LP, in macroscopy and microscopy.

Maximum inspiratory and expiratory pressures in the pre and postoperative periods of patients with incisional abdominal hernia corrected by Lázaro da Silva technique

OBJECTIVE

To verify the effect of longitudinal abdominal incisional herniorrhaphy on respiratory muscle pressure.

METHOD

The technique of incisional herniorrhaphy used was proposed by Lázaro da Silva. To measure the pressure, we used a water manometer in 20 patients, median age 48.5 years (range 24 70). We analyzed the maximum inspiratory pressure at the level of residual volume (IP-RV) and functional residual capacity (IP-FRC) and the maximum expiratory pressure of functional residual capacity (EP-FRC) and total lung capacity (EP-TLC) in the preoperative and late postoperative (40 90 days) periods, in 13 patients with large incisional hernias and in 7 patients with medium incisional hernias.

RESULTS

There was a significant increase in IP-FRC (p = 0.027), IP-RV (p = 0.011) and EP-TLC (p = 0.003) in patients with large incisional hernias. EP-FRC increased, but not significantly. In patients with medium incisional hernias, the changes were not significant.

CONCLUSION

Surgical correction of large incisional hernias improves the function of the breathing muscles; however, surgery for medium incisional hernias does not alter this function.

Effects of inferior splenic lobe pole fixation and gastrosplenic peritoneal membrane section on the vitality of the remanent of subtotal splenectomy in rats

PURPOSE

To investigate the vitality of the spleen lower pole after subtotal splenectomy with suture to the stomach and after posterior peritoneal gastro-splenic membrane section, using macro and microscopic evaluations.

METHODS

Sixty Wistar rats were used in this study and were randomly distributed in the three groups: Group 1: (n=20), subtotal splenectomy with lower pole preservation, Group 2: (n=20) subtotal splenectomy with lower pole preservation and suture to the stomach, Group 3: subtotal splenectomy with lower pole preservation and posterior peritoneal gastrosplenic ligament section. The animals were sacrificed 45 days after the surgery and the spleen lower poles were removed for macroscopic and microscopic examination.

RESULTS

All animals in this series survived. No macroscopic differences were encountered between the groups. Microscopic evaluation observed statistic difference concerning fibrosis between group 1 and 3 (p ≤ 0.05), but the analysis for necrosis and inflammation presented no differences.

CONCLUSION

Vitality of the spleen lower pole after subtotal splenectomy is minimally modified when it is fixed to the stomach or when the posterior peritoneal gastrosplenic ligament is resected.

Effect of total splenectomy in the lipid profile in mice

PURPOSE

To analyze total splenectomy effect on the lipid profile - total cholesterol, low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), very-low-density lipoprotein cholesterol (VLDL) and triglycerides levels, in Balb/c mice.

METHODS

Thirty Balb/c male mice, one (1) month old and average weight 26.2g ± 4.0 were used in the experiment. They were distributed into three groups of 10 animals each: a control group (non-operated), a simulation group (spleen manipulation) and the splenectomy group. The animals were subjected to blood sampling to measure plasma lipid levels, at three different times: before surgery, days 30 and 75 of the experiment.

RESULTS

Increased total cholesterol and LDL were observed in the control group from the start to end of the experiment. The simulation group showed increased rates of VLDL and triglycerides at the 30th and 75th days. Splenectomized animals showed no significant change.

CONCLUSION

Total splenectomy did not induce increased plasma lipids levels of in Balb/c mice.

Phagocytic function of lower spleen pole and autogenous splenic implants in rats

PURPOSE

To investigate whether there are differences between the phagocytic function of the remaining lower spleen pole after subtotal splenectomy and autogenous splenic implants.

METHODS

Thirty-six male Wistar rats, weighting 364 ± 60g were used. They were subjected to subtotal splenectomy preserving the lower spleen pole and to autogenous splenic implant in the greater omentum. Its viability was assessed microscopically. Phagocytic function was assessed by splenic uptake of the radioisotope-labeled colloid and by macrophages counting.

RESULTS

The viability of the autogenous splenic implant and of the lower spleen pole was found in 33 animals, with no difference between them. The weight of the implants was higher than the lower pole of animals from groups G1, G7, G30, G60 and G120. The implants phagocytic function by radioisotope uptake was higher than the lower pole in G7 and G120 groups and it did not differ from the other groups. The number of macrophages was higher in G1, G60, G90 and G120 and did not differ from the other groups.

CONCLUSION

Until the 16th week, the phagocytic function was more pronounced in autogenous splenic implants when compared with the lower spleen pole, but it became similar thereafter.

Micronucleus test in peripheral blood of rats treated with hyperbaric oxygen after subtotal splenectomy preserving the lower pole

PURPOSE

To assess the mutagenic potential of the oxygen inhalation therapy (HBO), by means of the micronucleus test, performed in peripheral blood of rats that underwent subtotal splenectomy with lower pole preservation (ESTPI), after HBO sessions or simulations.

METHODS

Eighteen male Wistar rats, were distributed into three groups of six animals: group 1 - submitted to ESTPI and HBO sessions; group 2 - submitted to ESTPI and HBO simulations; group 3 - underwent cyclophosphamide administration. In groups 1 and 2, blood samples from the animals' tails were collected before surgery (T0) and immediately after the 13th HBO session or simulation (T1). In group 3, tail blood samples were collected from animals before (T0) and 24 hours after (T1) cyclophosphamide (CP) delivery. The number of micronucleated normochromatic erythrocytes (MNNCE) was determined by blind counting 2000 normochromatic erythrocytes (NCE) per animal.

RESULTS

Micronuclei average after CP delivery in group 3 was higher than before its use, thus confirming the mutagenic activity of this drug (p=0.01). In groups 1 and 2, no significant difference in the average of Micronuclei was observed when comparing it to blood samples before and after the 13th HBO session or simulation.

CONCLUSION

The treatment protocol used in this study did not induce Micronucleus formation in animals submitted to ESTPI and HBO treatment or simulation.

Epidural anesthesia with ropivacaine with or without clonidine and postoperative pain in hemorrhoidectomies

PURPOSE

To determine the safety, pain intensity correlated with age and body mass index (BMI), epidural anesthesia with ropivacaine and clonidine in hemorrhoidectomy.

METHODS

Eighty patients, both genders, 20-70 years old, ASA I or II, for hemorrhoidectomy were randomly divided into two groups: Control (n=38), epidural anesthesia with 14 mL of ropivacaine 0.75 % plus 0.0266 mL/kg of 0.9% saline solution; Experimental (n=42) epidural anesthesia with 14 mL of 0.75% ropivacaine plus 4.0 mcg/kg of clonidine. In preoperative and postoperative period were evaluated: systolic blood pressure (SBP), diastolic blood pressure (DBP ), heart rate (HR ), pulse oximetry (SpO2), electrocardiography (ECG), pain intensity (VAS ) in four, eight and, 12 hours and analgesic consumption.

RESULTS

The VAS values differed between four, eight and 12 hours in the Experimental Group, where correlation of VAS 12h with age (p<0.05) occurred and not with BMI and more patients (p<0.05) did not receive analgesics. SBP, DBP, HR changed similarly in both groups at 15, 30 and 45 min. The ECG and SpO2 remained unchanged.

CONCLUSIONS

Clonidine (4mcg/kg) in epidural anesthesia with ropivacaine 0.75% in hemorrhoidectomy showed safety and greater analgesia within four hours. The pain at 12 hours showed correlation with age and not with body mass index.

Immunoexpression of proliferating cell nuclear antigen (PCNA) in spleen of splenectomized rats with preservation of inferior pole, submitted to hyperbaric oxygenation

PURPOSE

To analyze PCNA immunoexpression on the inferior pole of the spleen of splenectomized rats submitted to hyperbaric oxygenation (HBO).

METHODS

Were analyzed fragments of the inferior pole of the spleen of 20 male Wistar rats submitted to splenectomy with preservation of the inferior pole. The rats were divided in two groups: group A (n=10) without HBO and group B (n=10) submitted to HBO at 2, 5 atmospheres per 120 minutes, twice a day for three days and once a day for seven days. The groups were then subdivided in four subgroups: A15 (n=5), with euthanasia on the 15th day; A45 (n=5), with euthanasia on the 45th day; B15 (n=5) with euthanasia on the 15th day and B45 with euthanasia on the 45th day. Respectively on these days, fragments of the inferior pole of the spleen of all animals were collected and analyzed with the immunohistochemistry technique in order to evaluate PCNA expression.

RESULTS

There was an expressive increase in PCNA immunoreactivity in the group B. The 45 day postoperative period resulted in a higher level of positivity than the 15 day postoperative period (p<0.01).

CONCLUSION

The quantitative analysis of proliferating cell nuclear antigen positive suggests that hyperbaric oxygenation increases cellular proliferation, contributing to splenic regeneration.

Resultados da herniorrafia inguinal bilateral simultânea pela técnica de Lichtenstein

OBJETIVO: analisar os resultados da herniorrafia inguinal bilateral pela técnica de Lichtenstein. MÉTODOS: estudo dos prontuários de 59 pacientes submetidos à herniorrafia inguinal bilateral simultânea, eletiva, no período entre 2003 e 2007. Foram analisados: sexo, idade, peso, tempo operatório, tempo total de internação, classificação de Nyhus, intercorrências no pós-operatório imediato e tardio, e recidiva. Esses dados foram submetidos à análise estatística descritiva. RESULTADOS: dos 59 pacientes, 95% eram homens; e 5%, mulheres. A idade variou de 40 a 60 anos, o peso de 50 a 103 kg, o tempo operatório de 60 a 180 minutos, o tempo de internação de um a seis dias. Trinta pacientes apresentavam hérnias do tipo IIIB; nove, do tipo II; dez, do tipo IIIA; sete, do tipo IV; um, do tipo II à esquerda e tipo IIIB à direita; um, tipo IIIA à direita e IIIB à esquerda; e um, do tipo IIIA à direita e do tipo II à esquerda. No pós-operatório imediato, a dor foi a manifestação mais importante em 30,5% dos casos. Em 94,92% dos casos, não houve complicações tardias. Ocorreram dois casos de inguinodinia e um de dor em queimação local. Observou-se uma recidiva, no 29º mês de pós-operatório. CONCLUSÕES: a herniorrafia inguinal bilateral simultânea pela técnica de Lichtenstein foi segura e eficaz, pois houve baixo índice de complicações, curta permanência hospitalar e, em um período médio de 48 meses de acompanhamento, houve apenas um caso de recidiva.

A study of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) serum levels in rats subjected to fecal peritonitis and treated with intraperitoneal ropivacaine

PURPOSE

The objective of this study was to assess the cytokine serum levels of IL-6 and TNF-α in rats subjected to fecal peritonitis and treated with peritoneal lavage with 0.2% ropivacaine by peritoneal lavage.

METHODS

We subjected 16 Wistar rats to laparotomy 6 hours after the induction of fecal peritonitis with autogenous stool and subsequently divided the rats randomly into 4 groups: I-control, no treatment; II- drying of the abdominal cavity; III- lavage of the abdominal cavity with 3 mL of 0.9% normal saline and drying; IV- lavage of the abdominal cavity with 3 mL of 0.2% ropivacaine and drying. Six hours following the laparotomy, the animals underwent cardiac puncture, and 1 mL of blood was collected for cytokine assessment before the animals were euthanized.

RESULTS

The lavage with ropivacaine resulted in smaller TNF-α levels compared with those observed in the other treatment groups (p <0.05). Regarding IL-6, the ropivacaine group showed lower cytokine levels than those observed in groups I and II, but there was no significant difference (p> 0.05) between groups III and IV.

CONCLUSION

Peritoneal lavage with 0.2% ropivacaine was shown to reduce plasma levels of IL-6 and TNF-α in the treatment of fecal peritonitis in rats.

[Prehospital care to multiple victims with simulated trauma]

OBJECTIVE

To assess the quality of prehospital care agencies conducted in Vitória, capital of Espírito Santo State, Brazil.

METHODS

We conducted a retrospective study in the archives of the League of Academic Surgery and Trauma Care of Espírito Santo (Lacates) regarding 40 victims of a simulated crash between a bus and two cars. The patients were treated by four teams: Military Fire Department of Espírito Santo, Samu 192, County Guard and Civil Defense. The performance of these teams was evaluated by Lacates, through analysis of a check-list with pre-established guidelines for each victim.

RESULT

The Fire Department of Espírito Santo (CBMES), which extricated victims, outlined the danger zones and carried out the screening by the method START, acted correctly in 92.5% of cases. The Samu 192 victims, which attended victims by the mnemonic method (ABCDE) in medical outposts, acted correctly in 92.5% of cases in the category Airway; 97.5% in breathing, 92.5% in circulation, 90% in Neurological Assessment, and 50% in the Exhibition and Environmental Control. The analysis showed that the ABCDE care was correct in 42.5% of cases. The transport of patients was performed correctly in 95% of cases. The County Guard secured the patency of the avenues for transportation of patients and Civil Defense successfully coordinated the work of teams involved in the command post.

CONCLUSION

The triage and transport of victims have been performed satisfactorily. However, more attention should be given to exposure and hypothermia protection of victims, since this item compromised treatment.

Histological features of peritoneal lavage with ropivacaine in rats with fecal peritonitis

PURPOSE

To evaluate the histological features in lungs, peritoneum and liver of rats subjected to fecal peritonitis and treated with peritoneal lavage with 0.2% ropivacaine.

METHODS

Twenty Wistar rats were subjected to laparotomy 6 h after the fecal peritonitis induction with autogenous stool. Rats were randomly distributed into 4 groups: I - (n=5) Control, no treatment; II - (n=5) Drying of the abdominal cavity; III - (n=5) Abdominal cavity lavage with 3 ml 0.9% saline solution and drying; and IV - (n=5) Abdominal cavity lavage with 3 ml 0.2% ropivacaine and drying. The animals that died underwent necropsy, and the surviving ones were subjected to euthanasia on the 11th day post-surgery. Fragments of liver, lungs and peritoneum were removed for histological evaluation.

RESULTS

The animals that received peritoneal lavage (groups III and IV) showed greater survival than the drying and control groups. Lavage with ropivacaine prevented death during the observed period. Peritoneal lavage with ropivacaine maintained the architecture of the lung, peritoneum and liver without any important histological alterations. The histopathological findings analyzed correlated with greater survival of group IV.

CONCLUSION

Treatment of fecal peritonitis in rats with peritoneal lavage using 0.2% ropivacaine demonstrated a reduction in histopathological alterations related to inflammatory response and sepsis.

A new proposal to evaluate the healing of open skin wounds: volumetry

PURPOSE

To present a new proposal to evaluate the healing of an open subcutaneous and skin wound, which we termed "volumetry".

METHODS

A total of 32 circular wounds were performed in the subcutaneous tissues and skin of four feet of pigs (8 each). Each wound had about 1 cm in diameter and was 0.2 cm deep. Volume was calculated from the wound filled with saline and mass Xantopren. With the aid of a magnifying glass and local lighting, the liquid was dripped with a micropipette inside the wound until complete fullness. Volume repletion was calculated in microliters, corresponding to the volume of the wound. The mass of Xantopren was placed inside the wound to obtain a mold of the lesion. Mold volume was calculated using the formula of the volume of a cylinder closest resembling a geometric figure with mold.

RESULTS

The calculation of wound volume was possible with both Xantopren and mold techniques. Volume as calculated by micropipette was 119.37 ± 30.87 microliters while the volume calculated by mold was 122.41 ± 33.90 mm3 (p=0.79).

CONCLUSIONS

Volumetry in pig feet is simple and reproducible. Volumetry perfomed with saline did not differ from the volumetry with mass Xantopren. This method may be a useful tool to help evaluate the healing of open skin wounds in experimental and clinical research.

Colecistectomia videolaparoscópica em 960 pacientes idosos

OBJETIVO: Analisar o tempo operatório, a permanência hospitalar, a taxa de conversão, a morbidade e a mortalidade de pacientes idosos submetidos à colecistectomia videolaparoscópica por doença da vesícula biliar. MÉTODOS: Estudo descritivo, retrospectivo, realizado no prontuário de 960 pacientes, de ambos os sexos, com idade entre 60 e 97 anos no período de janeiro de 1993 a agosto de 2009. RESULTADOS: O tempo operatório variou de nove a 180 minutos. O tempo de internação variou de 24 a 120 horas. A conversão ocorreu em 28 pacientes (2,92%), dos quais 67,9% eram mulheres e 28,6% homens tendo sido em 11 casos (39,3%) realizada minilaparotomia e em 17 (60,7%) a via aberta convencional. As intercorrências no transoperatório foram duas rupturas da vesícula biliar, uma falha no pneumoperitônio e uma na clipagem do ducto cístico. No pós-operatório observaram-se cinco hérnias umbilicais incisionais. As complicações sistêmicas foram: nove arritmias cardíacas, uma icterícia pós-operatória, um infarto agudo do miocárdio e um infarto enteromesentérico. Mortalidade ocorreu em três pacientes (0,3%), um por infarto agudo do miocárdio no transoperatório, uma sepse e um infarto enteromesentérico. CONCLUSÃO: Os pacientes idosos submetidos à colecistectomia videolaparoscópica apresentaram baixo tempo de internação hospitalar e baixa morbimortalidade. O tempo operatório e o de internação hospitalar foram curtos, demonstrando que a colecistectomia videolaparoscópica é procedimento seguro e eficaz nos idosos.

Effect of hyperbaric oxygen therapy in rats with subtotal splenectomy preserving the inferior pole

PURPOSE: To evaluate the effect of hyperbaric oxygen therapy on the survival and weight of rats submitted to subtotal splenectomy and on the viability and growth of the inferior pole. METHODS: Forty Wistar rats underwent subtotal splenectomy with preservation of the inferior pole and distributed into two groups: Group A (n=20) - not treated with hyperbaric oxygen, Group B (n=20) - treated with hyperbaric oxygen. These groups were divided into two subgroups of 10 animals each, according to the time of euthanasia, 15th and 45th days. The survival and weight of the animals were recorded. The inferior pole was measured, weighed and morphologically analyzed. RESULTS: All animals survived. The weight of the animals increased in all subgroups, but decreased on the 10th day in the subgroups treated with hyperbaric oxygen (p<0.001). The viability of the inferior pole was more evident in animals treated on the 15th day, but did not differ on the 45th day. The growth of the inferior pole has not occurred on the 15th day but on the 45th day after surgery in untreated animals (p<0.01) and treated animals (p<0.05). Vascular and cellular increase in treated animals was significantly higher than in untreated ones. CONCLUSION: Hyperbaric oxygen therapy did not affect the survival of animals but reduced their weight. It improved the viability of the inferior splenic pole, but did not interfere with their growth.

Subtotal laparoscopic splenectomy in rats with preservation of the inferior pole

Purpose: To evaluate the feasibility and safety of subtotal splenectomy by laparoscopy with inferior pole preservation and to determine the viability of the splenic remnant. Methods: Twenty male Wistar rats weighing between 365 g and 474 g (mean 417.92 ± 36.15g SD) were operated and randomly assigned to two groups : Group 1 rats were killed on postoperative day 10 (n = 10), and Group 2 on the postoperative day 80 (n = 10). Both the inferior splenic pole and the superior part of the spleen, which was used as a control to measure inferior pole viability, were weighed and morphologically examined. Results: The technique was feasible in all cases. There were two postoperative deaths on immediate postoperative and one not well defined. The average weight percentage of the inferior pole, measured indirectly on the 10th day, was 53.67% ± 11.59% and on the 80th day was 62.69% ± 6.89%. The inferior pole was necrotic, with abscess formation in one case (5.9%) and appeared normal in all other cases. Microscopy showed features that were compatible with normality. Conclusions: Subtotal splenectomy with preservation of the inferior pole by laparoscopy was feasible and safety. The lower splenic pole was viable in 94.1% of animals.

Venous drainage from the tail of the pancreas to the lienal vein and its relationship with the distal splenorenal shunt selectivity

PURPOSE

To identify the veins draining from the pancreatic tail to the lienal vein and its possible relationship with the loss of the distal splenorenal shunt selectivity.

METHODS

Thirty eight human blocks including stomach, duodenum, spleen, colon and pancreas, removed from fresh corpses, were studied with the replenish and corrosion technique, using vinilic resin and posterior corrosion of the organic tissue with commercial hydrochloric acid, in order to study the lienal vein and its tributaries.

RESULTS

The number of veins flowing directly to the splenic vein varied from seven to twenty two (14.52 + or - 3.53). Pancreatic branches of the pancreatic tail flowing to the segmentary veins of the spleen were found in 25 of the anatomical pieces studied (65.79%). These branches varied from one to four, predominating one branch (60%) and two branches (24%).

CONCLUSIONS

In 65.79% of the anatomical pieces studied, the veins of the pancreatic tail flowed in segmentary branches of the splenic vein. These branches could be responsible for the loss of distal splenorenal shunt selectivity. The complete disconnection of the pancreatic tail could increase the selectivity in this procedure.

Aspectos morfológicos e funcionais dos autoimplantes esplênicos em ratos tratados com oxigenio hiperbárico

OBJETIVO: Estudar aspectos morfológicos e funcionais dos autoimplantes esplênicos de ratos submetidos ou não à oxigenioterapia hiperbárica (OHB). MÉTODOS: Foram estudados em dois períodos distintos 105 ratos Wistar. No período mediato (n= 56) os animais foram avaliados até o 11º dia de pós-operatório, e no período tardio (n= 49), até o 70º dia. Em cada período os ratos foram distribuídos nos grupos: A- Simulação, B- Autoimplante esplênico, tratados com oxigênio hiperbárico ou não. Nos animais do Grupo A realizou-se apenas manipulação do baço. Nos animais do Grupo B realizou-se esplenectomia total e a seguir quatro fragmentos do baço foram implantados no grande omento. Em todos os animais foram dosados os lípides e imunoglobulinas e contadas as plaquetas e os corpúsculos de Howell-Jolly no pré-operatório e no 11º ou 70º dia de pós-operatório. O baço dos animais do Grupo A e os autoimplantes dos animais do Grupo B foram retirados e enviados para avaliação morfológica. RESULTADOS: No grupo B11nt houve aumento do colesterol total, LDL-colesterol, VLDL-colesterol e triglicérides. No grupo B70nt houve aumento do colesterol total e LDL-colesterol. Nos grupos tratados não houve alterações lipídicas. A IgM caiu nos grupos B e não alterou nos grupos A. Os corpúsculos de Howell - Jolly foram menos freqüentes nos grupos Bt que nos grupos Bnt. As plaquetas aumentaram nos grupos B11t e B11nt e não se alteraram nos demais grupos. A viabilidade microscópica dos grupos Bt foi melhor que a dos grupos Bnt. CONCLUSÃO: Os autoimplantes esplênicos dos animais tratados com OHB apresentaram melhor função e viabilidade do que os autoimplantes dos animais não tratados.

Growth of the lower spleen pole remaining after subtotal splenectomy in rats

PURPOSE

To determine whether the lower pole of the spleen grows after subtotal splenectomy following ligature of major spleen blood vessels.

METHODS

Thirty-nine Wistar rats (328.8 +/- 27.8 g) submitted to subtotal splenectomy with preservation of the lower splenic pole were divided into two groups: group 1 (control, n=20), immediate removal of the lower pole; group 2 (n=19), removal of the pole on postoperative day 80. The length, width and thickness of the pole were measured. In the control group, mean percent pole weight was calculated immediately after surgery in a direct and indirect manner. In the first case, the weight of the lower pole was divided by overall spleen weight; in the second case, pole weight was divided by the ideal weight of the spleen obtained by linear regression analysis. The results of the two calculations were compared. Macro- and microscopic examinations of the pole were performed.

RESULTS

In group 1, no significant difference in mean percent pole weight was observed between the direct and indirect method. In group 2, mean percent pole weight obtained by indirect calculation on day 80 was higher than in group 1 (p<0.001). In group 2, mean length, width and thickness of the pole remnant increased from the first to the 80th day (p<0.05). Histological analysis showed preserved tissue architecture and features compatible with cell hyperplasia in group 2.

CONCLUSION

The lower pole splenic remnant presented statistically significant growth up to postoperative day 80 after subtotal splenectomy, even after ligature of the major spleen vessels. Light microscopy revealed changes compatible with cell hyperplasia.

Effects of peritoneal lavage with lidocaine on survival of rats with fecal peritonitis

PURPOSE

To study the effects of peritoneal lavage with a 2% lidocaine solution, on the survival of the rats submitted to peritonitis caused by their own feces.

METHODS

Forty-eight Wistar rats, weighting between 300 g and 330 g (mean, 311,45 +/-9,67 g), were submitted to laparotomy 6 hours following induction of fecal peritonitis. Animals were randomly divided into four groups of 12 each as follows: 1- Control, no therapy; 2- Drying of the abdominal cavity; 3- Peritoneal lavage with saline and drying; 4- Peritoneal lavage with a 2% lidocaine solution and drying. Animals that died were submitted to necropsy and the time of their death recorded; survivors were killed on the post-operation 11th day and necropsied.

RESULTS

Death occurred within 52 h in all animals of group 1; within 126 h in 100% of those of group 2; within 50 h in 50% of those of group 3. All animals of group 4 survived. Survival on the 11 th day was higher in groups 3 and 4 than in groups 1 and 2 (p<0.001), and higher in group 4 than in group 3 (p<0.01).

CONCLUSION

Peritoneal lavage with a 2% lidocaine saline solution without adrenaline, prevented the mortality of all animals with fecal peritonitis.

Epidural anesthesia using a 0,75% ropivacaine and subarachnoid anesthesia with a 0,5% bupivacaine associated or not with clonidine in hemorroidectomies

PURPOSE: To study the safety and efficiency of two anesthetic blockages in hemorroidectomy and the effect of clonidine on analgesia. METHODS: 80 patients were studied, randomly divided into four groups: l (n=19)- peridural with a 0,75% ropivacaine; 2 (n=21)-peridural with a 0,75% ropivacaine and 150 µg of clonidine; 3 (n=19)- subarachnoid with a 0,5% bupivacaine; 4 (n=21)- subarachnoid with a 0,5% bupivacaine and 50 µg of clonidine. The intensity of pain was evaluated by the visual analogical scale 8, 12 and 24 hours after surgery. The use of vasoconstrictors on the transoperatory and the amount of analgesics within the 24 hours were registered. RESULTS: The intensity of pain, 8 hours after surgery, was lesser on group 4, and much lesser on group 4 comparing with groups 1 and 2, 12 hours (p=0,022; p=0,001) and 24 hours (p=0,03; p=0,003). The frequency of vasoconstrictors usage on the transoperatory and the analgesics on the post-operatory showed no difference among the groups. There were no anesthetic complications. CONCLUSIONS: The subarachnoid anesthesia with a 0,5% bupivacaine with clonidine, showed better analgesia comparing with the peridural anesthesia with a 0,75% ropivacaine with or without clonidine, however all were safe and efficient. The clonidine aided on the decreasing of pain when subarachnoid anesthesia was used.

[Effects of two types of diet on plasma lipids in rats submitted to splenic surgery]

OBJECTIVE

The objective was to verify the effect of total splenectomy and ligature of the splenic vessels on the plasma lipid levels in rats fed a control diet or a diet supplemented with 2.5% cholesterol.

METHODS

Ninety-nine male Wistar rats weighting between 273 and 427 g (arithmetic mean: 349.46 +/-35.54) were randomly divided into four groups: group 1- control (N=19), nonoperated; group 2 - sham (N=19), laparotomy with spleen manipulation; group 3 -TS (N=31), total splenectomy; group 4 (N=30) simultaneous ligature of the splenic artery and vein. Blood was collected from all animals for determination of plasma lipids at the beginning of the experiment. Rats were than divided into two subgroups receiving either control diet (subgroup A) or diet supplemented with 2.5% cholesterol (subgroup B). Another blood sample was collected 90 days later for a new determination.

RESULTS

No significant difference in plasma lipids between the four groups was observed at the beginning (p>0.05). In subgroups 1A, 2A and 4A, there was no significant difference in the values of HDL, VLDL and triglycerides, except LDL that dropped significantly in subgroup 1A and 2A (p<0.05) and not significantly in subgroup 4A. In subgroup 1B, 2B and 4B there was a significant increase in late postoperative plasma total cholesterol, LDL, VLDL (p<0.05) and a not significant increase of HDL. In total splenectomy, at late postoperative there was a significant increase of cholesterol, LDL, VLDL and triglycerides, especially in subgroup B. In group 3 the cholesterol, LDL and triglycerides were more significant than in groups 1, 2 and 4.

CONCLUSION

Total splenectomy caused a more significant increase of cholesterol, LDL, VLDL and triglycerides in rats fed a cholesterol diet. The simultaneous ligature of vein and artery prevented alterations in plasma lipids observed in rats submitted to total splenectomy and maintained lipid levels similar to those of the control and sham groups.

Comparative study of the resistance of manual and mechanical sutures in the bronchial stump of dogs submitted to left pneumonectomy

OBJECTIVE

To compare the resistance of manual suture with that of mechanical suture immediately after the suture of the left bronchial stump of dogs submitted to pneumonectomy.

METHODS

A total of 15 mixed-breed dogs of both genders, each weighing between 8 and 23 kg, were randomly divided into 2 groups. In group I (n = 7), the bronchial stump was sutured manually (the Sweet method) and, in group II (n = 8), it was stapled. Immediately after the closure of the bronchial stump, the intratracheal pressure was progressively increased in a controlled manner.

RESULTS

The mean rupture pressure of the bronchial stump suture line was 33.71 mmHg in group I and 89.87 mmHg in group II (p < 0.01).

CONCLUSION

These data allowed us to conclude that mechanical suture of the bronchial stump, submitted to pressure immediately after closure, is more resistant than is manual suture in dogs submitted to pneumonectomy.

Preservative spleen surgery and hyperbaric oxygen therapy

PURPOSE: To assess functional and morphological aspects of spleen auto-implants and of the splenic inferior pole of rats, post-operatively treated or not with hyperbaric oxygen, as well as the survival of these animals, were studied. METHODS: Seventy-eight male Wistar rats, weighing between 192 and 283 g ( 238,3 ± 9,6g), were randomly distributed into three groups: Group1-(n=20), spleen manipulation; group 2-(n=36), spleen auto-implantation; group3-(n= 22), subtotal splenectomy preserving the inferior pole. Each group was subdivided as follows: subgroup a, not submitted to hyperbaric oxygen therapy: 1a(n=10), 2a(n=21), 3a(n= 13); subgroup b, submitted to the therapy: 1b(n=10), 2b(n=15), 3b(n=9). Blood was collected pre-operatively and 11 days after surgery, for the estimation of lipids and immunoglobulins and the counting of platelets and Howell-Jolly corpuscles. The spleen and remains were taken for histological study. RESULTS: The number of surviving animals was significantly higher in groups 1(p<0,01) and 3(p<0,05) relative to those of subgroup 2a. Total cholesterol and the LDL fraction increased significantly in subgroup 2a (p<0,01) and 3a (p<0,05), and remained unaltered in subgroups 2b e 3b. IgM decreased more significantly in subgroup 2 than in subgroup 3 (p<0,001 vs p<0,01). The increase of platelet numbers and the appearance of Howell Jolly corpuscles was smaller in subgroup 2b compared to subgroup 2a , and in group 3 compared to group aqui-> 2. The macro and microscopic appearance in subgroup 2b were more viable than in subgroup 2a, and that of group 3 more viable than in group 2. The survival of the animals carrying their whole spleen or its inferior pole was more frequent than that of the auto-implanted animals. CONCLUSION: Functionality and viability of the whole spleen or of its inferior pole, were better than in the auto-implanted animals. Hyperbaric oxygentherapy contributed to increased survival frequency of auto -implanted animals, and to improve the functionality and viability of the auto-implants and the function of the inferior splenic pole, and did not interfere in animals carrying their whole spleen.

Subtotal splenectomy preserving the lower pole in rats: technical, morphological and functional aspects

PURPOSE: To assess the possibility of preserving the lower pole of the spleen, supplied by the inferior lobar vessels and segmental vessels, or by vessels of the gastrosplenic ligament, in subtotal splenectomy; to study the viability and function of the lower pole of the spleen. METHODS: Thirty-six male Wistar rats were used in this study. Said animals weighed 273-390 g ( 355.2 ± 30.5 g ), and were randomly distributed into three groups. Group 1 comprised ten animals which were submitted to exploratory laparotomy with spleen manipulation (sham operation). Group 2 comprised 16 animals which were submitted to total splenectomy. Group 3 comprised ten animals which were submitted to subtotal splenectomy, preserving the lower pole of the spleen. Blood was collected from all animals before and 90 days after surgery to measure the levels of cholesterol and triglycerides. The animals were sacrificed 90 days after surgery. Spleens and remaining spleens were removed for macroscopic and microscopic examination. RESULTS: Surgery was performed with no complications in all groups. Six animals died in group 2. Spleens of groups 1 and 2, and lower poles of group 3 were macroscopically viable. Apparent white pulp hyperplasia was observed in group 1. In group 3, slight inflammation and capsular fibrosis were observed at the incision site, as well as diffuse hemosiderosis in the red pulp. Average mass of remaining spleen was 35.84% ± 4.31%. No significant difference was observed between preoperative and late postoperative lipid levels in groups 1 and 3 (p > 0.05). Late postoperative lipid levels significantly increased in group 2. CONCLUSIONS: Preservation of the lower pole of the spleen (supplied by gastrosplenic vessels or inferior lobar vessels and segmental vessels) was possible with subtotal splenectomy. The lower pole was macroscopically and microscopically viable in all cases. Subtotal splenectomy preserving the lower pole prevented changes in lipid levels, which were observed in rats submitted to total splenectomy. Plasma lipid levels in rats submitted to subtotal splenectomy were similar to those observed in sham operated rats.

Subtotal splenectomy preserving the lower pole in rats: technical, morphological and functional aspects

PURPOSE

To assess the possibility of preserving the lower pole of the spleen, supplied by the inferior lobar vessels and segmental vessels, or by vessels of the gastrosplenic ligament, in subtotal splenectomy; to study the viability and function of the lower pole of the spleen.

METHODS

Thirty-six male Wistar rats were used in this study. Said animals weighed 273-390 g ( 355.2 +/- 30.5 g ), and were randomly distributed into three groups. Group 1 comprised ten animals which were submitted to exploratory laparotomy with spleen manipulation (sham operation). Group 2 comprised 16 animals which were submitted to total splenectomy. Group 3 comprised ten animals which were submitted to subtotal splenectomy, preserving the lower pole of the spleen. Blood was collected from all animals before and 90 days after surgery to measure the levels of cholesterol and triglycerides. The animals were sacrificed 90 days after surgery. Spleens and remaining spleens were removed for macroscopic and microscopic examination.

RESULTS

Surgery was performed with no complications in all groups. Six animals died in group 2. Spleens of groups 1 and 2, and lower poles of group 3 were macroscopically viable. Apparent white pulp hyperplasia was observed in group 1. In group 3, slight inflammation and capsular fibrosis were observed at the incision site, as well as diffuse hemosiderosis in the red pulp. Average mass of remaining spleen was 35.84% +/- 4.31%. No significant difference was observed between preoperative and late postoperative lipid levels in groups 1 and 3 (p > 0.05). Late postoperative lipid levels significantly increased in group 2.

CONCLUSIONS

Preservation of the lower pole of the spleen (supplied by gastrosplenic vessels or inferior lobar vessels and segmental vessels) was possible with subtotal splenectomy. The lower pole was macroscopically and microscopically viable in all cases. Subtotal splenectomy preserving the lower pole prevented changes in lipid levels, which were observed in rats submitted to total splenectomy. Plasma lipid levels in rats submitted to subtotal splenectomy were similar to those observed in sham operated rats.

Níveis de lípides plasmáticos em ratos submetidos à esplenectomia total, ligadura simultânea dos vasos esplênicos e à esplenectomia subtotal com preservação do pólo inferior

OBJETIVO: Verificar o efeito da esplenectomia total, da ligadura dos vasos esplênicos principais e da esplenectomia subtotal com preservação do pólo inferior, nos lípides plasmáticos de ratos alimentados com dieta-controle ou dieta acrescida com 2,5% de colesterol. MÉTODO: Foram utilizados 111 ratos Wistar, machos, pesando entre 273g e 427g, com idade aproximada de 12 semanas, assim distribuídos: Grupo 1, controle (N = 20), não operado; Grupo 2 (N = 20) submetido à manipulação do baço; Grupo 3 (N = 31) submetido à esplenectomia total; Grupo 4 (N = 20), ligadura simultânea da artéria e veia esplênicas; Grupo 5 (N = 20), esplenectomia subtotal com preservação do pólo inferior. Foram dosados os lípides plasmáticos, e os ratos foram distribuídos em dois subgrupos, de acordo com a dieta (Subgrupo A- dieta-controle; Subgrupo B - dieta acrescida com 2,5% de colesterol). Todos os animais foram submetidos à nova colheita de sangue após 90 dias do início do experimento. RESULTADOS: Os animais submetidos à esplenectomia total, independentemente do tipo de dieta, apresentaram aumento significante (p < 0,05) do colesterol total, LDL, VLDL e triglicérides. O aumento da HDL foi significante nos ratos alimentados com dieta-controle (p < 0,05) e não significante nos alimentados com dieta acrescida com 2,5% de colesterol (p > 0,05). Os animais submetidos à ligadura simultânea da artéria e veia esplênicas e à esplenectomia subtotal com preservação do pólo inferior e alimentados com dieta-controle, não apresentaram alterações nos níveis de lípides plasmáticos, exceto pelo aumento da HDL (p < 0,05) observado no grupo da esplenectomia subtotal. Nos animais desses grupos, alimentados com dieta acrescida com 2,5% de colesterol, houve aumento significante de colesterol total, LDL, e VLDL e triglicérides. CONCLUSÕES: A esplenectomia total produz aumento significante do colesterol total, das frações LDL e VLDL e dos triglicérides, tanto nos ratos alimentados com dieta-controle quanto nos alimentados com dieta acrescida com 2,5% de colesterol. O aumento é mais significante nos animais alimentados com dieta acrescida com 2,5% de colesterol. A ligadura simultânea da artéria e veia esplênicas e a esplenectomia subtotal com preservação do pólo inferior previnem contra as alterações dos níveis de lípides plasmáticos observadas em ratos submetidos à esplenectomia total alimentados com dieta-controle ou acrescida com 2,5% de colesterol.

Viabilidade do baço de ratos após a ligadura simultânea da artéria e veia esplênicas

OBJETIVO: A ligadura simultânea da artéria e veia esplênicas, com preservação do baço, é realizada em seres humanos, na pancreatectomia caudal, mas o efeito exato dessa ligadura sobre o baço não é bem conhecido. O objetivo deste trabalho foi verificar o efeito da ligadura dos vasos esplênicos principais no baço de ratos. MÉTODO: Foram operados 58 ratos Wistar, machos, variando entre 230 e 408 g de peso. Os animais foram divididos aleatoriamente em dois grupos: grupo 1, simulação (N=23), submetido à laparotomia e manipulação do baço; grupo 2 (N=35) submetido à ligadura simultânea da artéria e veia esplênica. Todos os animais foram mortos 12 dias após a operação. O baço era retirado, pesado, fixado em formol a 4%, incluído em parafina, e os cortes foram corados pela hematoxilina e eosina para exame microscópico. RESULTADOS: O baço era normal em todos os animais do grupo 1 e em três dos 34 animais ( 8,82%) do grupo 2. Ocorreu infarto branco parcial do baço em 91,18% dos animais do grupo 2. O percentual médio de massa esplênica viável nos baços com infartos foi de 56,9 + 21,8 %. O aspecto histopatológico mostrou arquitetura preservada na porção não infartada, e neoformação conjuntivo-vascular cicatricial substituindo as áreas necrosadas. CONCLUSÕES: A ligadura simultânea da artéria e veias esplênicas resultou em infarto branco parcial do baço em 91,2% dos animais, com preservação mínima de 35% e média de 56,9% de massa esplênica viável. Na maioria dos animais que sofreram ligadura, o infarto se localizou na porção inferior do baço.

Viabilidade do baço de ratos após a ligadura dos vasos esplênicos: efeito do tratamento com oxigênio hiperbárico

OBJECTIVE

To investigate the effects of splenic artery and vein ligation and the influence of hyperbaric oxygen after the double vascular ligation on the viability of spleen tissue.

METHODS

Sixty nine adult male Wistar rats (285-375 g) were randomly separated in three groups: group 1, four rats, sham operated, group 2, 34 rats, submitted to simultaneous splenic artery and vein ligation and group 3, 31 rats, submitted to hyperbaric oxygen during 11 days, after double vascular ligation. All animals were killed on day 12 after surgery. The spleen was removed and paraffin embedded for microscopic examination.

RESULTS

In the groups submitted to vascular ligation, the spleen was normal in 8.82% of rats not treated with hyperbaric oxygen and in 45.16% of rats that received hyperbaric oxygen after vascular ligation (p=0.01). In the spleens with white infarct, the mass of preserved splenic tissue in relation to the total body mass did not differ between the groups treated or not with hyperbaric oxygen. The preserved splenic tissue had normal histology in both groups. The healing process was more accelerated in the group of rats treated with hyperbaric oxygen.

CONCLUSION

Results demonstrate that exposure to hyperbaric oxygen increased the frequency of total spleen mass preservation after simultaneous ligation of the splenic artery and vein but did not alter the percentage of the spleen's viable area, however the healing process in necrotic areas was accelerated.

Lipídios plasmáticos após esplenectomia total e parcial em cães

OBJETIVO: Avaliar o efeito da esplenectomia total e parcial (hemiesplenectomia e esplenectomia subtotal) no lipidograma de cães. MÉTODO: Foram operados 38 animais, adultos, machos, mestiços, com peso entre 13kg e 15kg. No pré-operatório, depois do exame clínico e jejum de 12 horas de uma dieta-padrão, foram realizados hemograma e lipidograma. Após anestesia geral com tiopental sódico os cães foram submetidos à laparotomia mediana supra e infra-umbilical. Procedeu-se no grupo 1, de sete cães, apenas à manipulação do baço (simulado); no grupo 2, de nove cães, à hemiesplenectomia cranial; no grupo 3, de nove cães, à esplenectomia subtotal, com preservação do pólo inferior do baço, após ligadura e secção dos troncos principais dos vasos esplênicos próximos ao hilo; e no grupo 4, de 13 cães, à esplenectomia total. RESULTADOS: No grupo 4 (esplenectomia total), quando comparamos os valores do lipidograma dos diferentes períodos pós-operatórios com os do pré-operatório, os nossos resultados mostraram que houve aumento significante do colesterol total em todos os períodos pós-operatórios (p < 0,05, p < 0,01). O HDL aumentou significantemente no 7º (p < 0,01) e 28º dias de pós-operatório (PO) (p < 0,05), e não significantemente (p>0,05) no 56º PO. O LDL aumentou significantemente no 56º PO (p < 0,01) em relação também aos demais períodos do pós-operatório. Os triglicerídeos e VLDL não apresentaram alterações significantes. Nos animais dos grupos 1 e 3 não houve alterações significantes. Nos do grupo 2, houve aumento significante do colesterol no 7º PO. Não houve diferença estatisticamente significante de peso entre os remanescentes das esplenectomias parciais. CONCLUSÕES: A análise dos resultados nos permitiu concluir que a esplenectomia total induz aumento significante do colesterol total, das frações HDL e LDL, enquanto os níveis de triglicerídios e a fração VLDL não sofrem alterações; a conservação da metade inferior do baço ou a esplenectomia subtotal, com preservação do pólo inferior, protege o animal de alterações lipídicas significantes.

Esplenectomia subtotal, em cães, com preservação do pólo inferior(PI) suprido por vasos do ligamento gastroesplênico

O objetivo desse trabalho foi estudar a viabilidade do pólo inferior (PI) do baço de cães, após a ligadura e secção da artéria e veia esplênicas. Foram operados 24 cães, mestiços, machos, com peso variando entre 12kg e 14kg. Os animais anestesiados foram submetidos a laparotomia mediana supra e infra-umbilical, com 12cm de comprimento. Nos do grupo 1 fez-se a ligadura e secção da porção superior do ligamento gastroesplênico, ligadura e secção da artéria e veia esplênicas. Após a ligadura do ramo descendente dos vasos esplênicos, o baço foi seccionado transversalmente, a superfície de corte do PI foi suturada e a peça enviada para estudo microscópico. A parede abdominal foi suturada por planos. Os cães foram mantidos vivos e sacrificados no sétimo (subgrupo I A - quatro cães), 15° (subgrupo 18 - cinco cães), trigésimo (subgrupo I C - quatro cães) e septuagésimo dia (subgrupo I D - três cães). Nessa ocasião, o Pl foi retirado para estudo. No grupo 2, três cães foram submetidos a laparotomia e manipulação do baço (controle 2 - simulação), para controle morfológico. Esse procedimento foi feito no 15° dia (subgrupo 2A - dois cães) e no sexagésimo dia (subgrupo 28 - um cão). Dos 24 cães operados, cinco foram a óbito. A causa foi evisceração (dois cães), hemorragia intraperitoneal (um cão), hemorragia digestiva baixa de causa não esclarecida (um cão) e indeterminada (um caso). O exame macroscópico do PI comparado àquele dos controles I e 2 mostrou aspecto duvidoso em apenas dois casos, onde o PI apresentava-se aderido firmemente à parede abdominal e alças intestinais. Não houve, no entanto, diferença estatisticamente significante (p>O.O5 - teste exato de Fisher) no número de casos viáveis entre os grupos controles e grupo I. O exame microscópico do PI, comparado àqueles do restante do baço (controle I) e ao controle 2 (simulação), mostrou que a referida porção apresentou alterações morfológicas discretas, na maioria dos casos, e sinais de regressão em dois casos. Esse número não induziu, também, resultados estatisticamente significante (p>O.O5). A análise dos nossos resultados nos permitiu concluir que o PI do baço de cães manteve-se viável em 86,6% dos casos, mesmo com a ligadura da artéria e veia esplênicas.