Effect of uterine artery ligation on ovulation in the rat.

Female rats were divided into six groups: (1) control, (2) one uterine artery (a.) ligated near the utero-tubal (U-T) junction, (3) one uterine a. ligated at the level of the cervix, (4) both uterine aa. ligated separately at the U-T junction, (5) both uterine aa. ligated separately at the cervix and (6) both uterine aa. tied with one ligature at the cervix. Segmental aa. were disrupted in all experimental groups except group 6. Animals were allowed to recover for ten days and killed the first metestrus thereafter. Number of eggs ovulated was determined by flushing the oviduct with saline solution and counting the ova. Control rats ovulated 5.0 +/- 0.4 eggs per ovary. Groups 2 and 3 had an increase in the number of eggs shed from the ovary on the non-ligated side. In contrast, a decrease in the number of ova shed occurred on the ligated side. When both aa. were ligated separately (groups 4 and 5), irrespective of location, a decrease in the number of eggs shed by both ovaries was evident. No effect was found when only one ligature was placed near the cervix (group 6). The data demonstrate that blood supply to the ovary via the uterine artery is essential for the full complement of eggs to be shed.     

Changes in inflammatory mediators in experimental periodontitis in the rhesus monkey.

Ligature-induced periodontitis was monitored for 6 months in eight Macaca mulatta monkeys to examine clinical status, radiographic bone level, and crevicular fluid (CF) levels of prostaglandin E2 (PGE2), thromboxane B2 (TxB2), interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha, and leukotriene B4 (LTB4). A split-mouth design was used, with eight ligated teeth and eight contralateral nonligated teeth which develop soft-chow-promoted (spontaneous) disease. Ligated sites experienced an average attachment loss of 0.94 mm per site and linear bone loss of 0.88 mm per site, with spontaneous-periodontitis sites experiencing approximately half the loss of ligated sites. The CF mediator levels showed increased levels of PGE2 and TxB2 at the ligated sites, as compared with the spontaneous sites, with no significant contralateral differences in the IL-1 beta or LTB4 responses. The concentrations of LTB4 in CF reached an early threefold peak over the baseline level at 1 month. By 2 months there was a statistically significant threefold elevation in CF-PGE2 in the ligated sites and a twofold elevation in the spontaneous sites as compared to the baseline level (P = 0.041 and 0.008, respectively). The monocyte product IL-1 beta increased sharply at 2 months and returned to the baseline level by 6 months at both ligated and nonligated sites. Tumor necrosis factor alpha in CF was below the limit of detection at all sites throughout the experiment (i.e., < 2 ng/ml). The selective elevation of both PGE2 and TxB2 in ligated sites, compared with levels in spontaneous sites, in the presence of similar levels of LTB4 and IL-1 beta provides further evidence that these molecules regulate the magnitude of the tissue-destructive response in progressive periodontitis.     

Cholera toxin and Salmonella typhimurium induce different cytokine profiles in the gastrointestinal tract.

Salmonella infection of the gastrointestinal tract (GT) results in fluid secretion and inflammation. In contrast, cholera toxin (CT) induces fluid secretion but no inflammation. Using a murine ligated intestinal loop model, we investigated cytokine production (interleukin-1 [IL-1], IL-2, IL-4, IL-6, IL-10, gamma interferon, and tumor necrosis factor alpha) in the GT following exposure to these agents. Salmonella typhimurium induced a Th1-like cytokine profile in loops obtained from either nonimmune mice or Salmonella-immunized mice. CT induced only IL-6 and IL-10 production in ligated loops from nonimmune mice but induced a Th2-like cytokine profile in ligated loops obtained from CT-immunized mice. These results show that CT and S. typhimurium induce very different cytokine profiles in the GT.     

The effect of a modified blood supply on the craniofacial growth of rabbits. 2. Masticatory muscles

After ligation of the right common carotid artery, the dry weight of the muscles of mastication on the ligated side did not differ from that of the control animals between the 45th and 225th d of life. On the opposite side, however, the muscles were in some cases significantly heavier than those of the control animals, particularly in male rabbits with ligated common carotid arteries. The methodical application of these results is proposed.     

Association of Escherichia coli with the Small Intestinal Epithelium II. Variations in Association Index and the Relationship Between Association Index and Enterosorption in Pigs

The association between small intestinal epithelium and enteropathogenic Escherichia coli (EEC) was studied in ligated intestinal loops of pigs and rabbits. The association indexes (degree of association) for each of two porcine EEC strains varied widely among pigs and independently of each other. Significant litter-to-litter variations in association indexes among colostrum-deprived newborn pigs were interpreted to be the result of congenital resistance to association with specific EEC in some pigs. Since enterosorption occurred in loops with low association indexes, it was not necessary for EEC to establish a high association index for them to cause enterosorption in ligated intestinal loops. Two strains of EEC which are enteropathogenic for humans caused enterosorption in ligated loops in pigs 3 weeks old or less but not in 6-week-old pigs.     

Effect of the estrous cycle on uterine infection induced by Escherichia coli.

Escherichia coli was inoculated into the uterine lumen of rats and rabbits at different estrous stages; one uterine horn of each animal was ligated at the cervical end. In rats, a large number of E. coli were retained in the ligated horns regardless of the estrous stage. E. coli inoculated at diestrus or pseudopregnancy induced purulent endometritis, but when inoculated at proestrus-estrus the organism caused asymptomatic infection. In nonligated horns, few E. coli were recovered, and marked histopathological changes were not observed. Large numbers of E. coli were retained in the nonligated horn at proestrus as a result of physiological constriction of the cervix. E. coli inoculated at proestrus never caused purulent endometritis in either the ligated horn or the nonligated horn. In rabbits, E. coli infused into ligated horns brought about purulent inflammation irrespective of ovarian states. The number of recoverable E. coli was reduced rapidly at the follicular phase as compared with the luteal phase. These results suggest that the stage of the estrous cycle when animals are inoculated with E. coli influences the course of the uterine infection.     

Effects of immunization with B. macacae on induced periodontitis--preliminary findings

This preliminary study examined the effects of immunization with Bacteroides macacae, the monkey equivalent of the human species of B. gingivalis on ligature-induced periodontitis. During a 12 week immunization period, 8 out of the 12 Macacae fasicularis monkeys were immunized weekly with B. macacae washed cells and 4 were sham-immunized with saline. At the same time, all were scaled and pumiced weekly to establish gingival health. Following this period, the mandibular first molars were ligated in 8 out of the 12 monkeys to induce periodontitis. The immunized, ligated experimental group, the ligated, sham-immunized control group, and the immunized, non-ligated control group were then followed for a 6 months ligation period while plaque was allowed to accumulate. Gingival indices, attachment levels, pocket depths, plaque indices, radiographs, serum and crevicular fluid antibodies and subgingival bacteria were assessed. Immunization led to elevated antibody levels to B. macacae while ligation increased plaque, gingival inflammation, and bone loss. Following the 6 month ligation period, B. macacae comprised 1.7% of the cultivable flora in the immunized, non-ligated monkeys, 2.1% in the immunized, ligated monkeys, and 5.6% in the sham-immunized, ligated monkeys. Similar differences between the immunized, ligated and and the sham-immunized, ligated groups were not seen for B. intermedius, nor B. melaninogenicus. These results suggest a heightened humoral response to B. gingivalis reduces subgingival re-colonization by this organism and modulates the course of ligature-induced periodontitis.     

The role of liver and kidneys in the removal of circulating hyaluronan. An experimental study in the rat

The concentration of circulating hyaluronan was determined in rats after either the liver or the kidneys had been excluded from the systemic circulation. Both conditions caused an increase of the serum levels of hyaluronan. However, the rate of increase was more rapid in the animals with ligated hepatic vessels compared to those with ligated renal vessels. This in vivo investigation indicates that in the rat both kidney and liver systems are important for the removal of hyaluronan from the blood.     

Pathogenic properties of Campylobacter jejuni: assay and correlation with clinical manifestations.

The pathogenic properties of 20 strains of Campylobacter jejuni isolated from persons with clearly defined clinical manifestations were determined. Cell-free broth filtrates were examined for (i) enterotoxin production by Chinese hamster tissue culture assay and an enzyme-linked immunosorbent assay (ELISA) employing GM1 ganglioside and affinity-purified antiserum to Escherichia coli heat-labile toxin, (ii) cytotoxin production by Vero and HeLa cell tissue culture lines, and (iii) their ability to cause fluid secretion in rat ligated ileal loops. Viable bacteria were examined for invasive properties by an ELISA with the immunoglobulin fraction of antiserum to Formalin-killed bacteria of an invasive strain, and by their effect on fluid secretion and morphology in rat ligated ileal loops. None of the eight isolates obtained from asymptomatic carriers had any detectable pathogenic properties. All six strains isolated from persons with bloody invasive-type diarrhea elaborated a cytotoxin; their viable bacteria had high titers in the ELISA for invasive properties and caused fluid secretion in ligated ileal loops, although consistent morphologic abnormalities and evidence of mucosal invasion, examined by immunofluorescence techniques, were not detected. All six strains isolated from persons with watery secretory-type diarrhea produced an enterotoxin, one elaborated a cytotoxin, and broth filtrates of all strains caused fluid secretion in ligated ileal loops; viable bacteria had low titers in the ELISA for invasive properties and evoked fluid secretion in ligated loops by means of enterotoxin production. These observations show (i) that a correlation exists between the pathogenic properties of the infective C. jejuni strain and gastrointestinal manifestations in the infected host, and (ii) that these pathogenic properties can be identified by in vitro assays, including ELISAs.     

Isolation and partial characterization of two different heat-stable enterotoxins produced by bovine and porcine strains of enterotoxigenic Escherichia coli.

Heat-stable enterotoxins (ST-124 and ST-1261) have been isolated from two different enterotoxigenic Escherichia coli of bovine (124) and porcine (1261) origin. The enterotoxin preparations were isolated by ultrafiltration and ion-exchange chromatography and were both active in the suckling mouse test and pig ligated loop test in the nanogram range. The bovine (ST-124) enterotoxin was not stable to heating in its isolated form, and significant differences in amino acid composition were observed between the two enterotoxins. Although both toxins were active at similar levels in the suckling mouse and pig ligated loop tests, ST-124 lacked the ability to cause the profound secretory responses seen with ST-1261 in the weanling pig ligated loop.     

Portal branch ligation in the rat. Reevaluation of a model.

The effects of portal occlusion on the liver have been differently reported in different studies. The authors therefore reevaluated a model of portal branch ligation (PBL) in the rat. Histologic appearance, DNA synthetic activity, labeling count, and mitotic index were serially evaluated in both ligated and nonligated parts of the liver after interruption of the portal flow to one fourth, one third, and two thirds of the liver mass. The authors confirmed the presence of compensatory hyperplasia induced in the nonligated liver lobe(s) by PBL, and its intensity was roughly proportional to the amount of liver tissue devoid of portal perfusion. Portal-deprived liver tissue underwent a rapid and progressive atrophy, and, by the end of the first week, the weight of this part had decreased 10-fold. By a balance between atrophy and compensatory growth, the total liver weight was maintained at the level of sham-operated animals throughout the experiment. PBL invariably resulted in early centrilobular necrosis, which occupied 15-24% of the ligated lobe(s). However, already after 4 days it was almost totally resorbed and did not appear de novo. PBL was not followed by local collateralization.     

Effect of uterine artery ligation on ovulation in the rat

Female rats were divided into six groups: (1) control, (2) one uterine artery (a.) ligated near the utero-tubal (U-T) junction, (3) one uterine a. ligated at the level of the cervix, (4) both uterine aa. ligated separately at the U-T junction, (5) both uterine aa. ligated separately at the cervix and (6) both uterine aa. tied with one ligature at the cervix. Segmental aa. were disrupted in all experimental groups except group 6. Animals were allowed to recover for ten days and killed the first metestrus thereafter. Number of eggs ovulated was determined by flushing the oviduct with saline solution and counting the ova. Control rats ovulated 5.0 ± 0.4 eggs per ovary. Groups 2 and 3 had an increase in the number of eggs shed from the ovary on the non-ligated side. In contrast, a decrease in the number of ova shed occurred on the ligated side. When both aa. were ligated separately (groups 4 and 5), irrespective of location, a decrease in the number of eggs shed by both ovaries was evident. No effect was found when only one ligature was placed near the cervix (group 6). The data demonstrate that blood supply to the ovary via the uterine artery is essential for the full complement of eggs to be shed.     

A modified Sperber technique for direct estimation of true renal tubular excretion fraction.

The Sperber technique in the hen is particularly suitable for the study of renal tubular secretion. However, results obtained with this technique vary considerably, due to an unpredictable and highly variable shunting of renal portal blood. In an attempt to get a total and stable renal perfusion by portal blood from the leg, appropriate shunt vessels were ligated. This procedure was found to force all portal blood from the leg to perfuse the ligated kidney, without affecting the symmetry of glomerular filtration or renal clearance of 125-I-Na-o-iodohippurate between the kidneys. In conclusion, the abolition of renal portal shunt flow allows use of the Sperber technique for a direct estimation of the true tubular excretion fraction (TTEF) of a substance. Thus, TTEFPAH, a measure of the tubular excretion efficiency of para-amino-hippuric acid, was found to be about 70%. The stable renal perfusion in ligated animals will also facilitate comparative studies of renal tubular excretion in the hen. Moreover, no animal has to be rejected due to a low renal perfusion of portal blood. Furthermore, the use of ligated hens makes it unnecessary to use markers for the renal perfusion of portal blood when steady-state experiments are performed. Finally, the total renal perfusion of portal blood in ligated animals will facilitate the demonstration of a secretory component in the renal handling of substances with a low affinity for the renal transport system.     

Prolonged bile duct obstruction: a new experimental model for cirrhosis in the rat.

Hepatic morphological abnormalities were examined in rats whose bile ducts had been either cannulated and then obstructed or irreversibly ligated for 5, 10, 15 and 28 days or longer. Throughout the experiment most of the morphological changes observed in the cannulated group were comparable to those in the ligated group. Portal inflammation and marginal bile duct proliferation were noted with the same frequency in both groups. Biliary obstruction for 15 days or more led to cirrhosis. After 28 days obstruction, five out of six cannulated rats and four out of six ligated animals respectively developed cirrhosis. The development of cirrhosis was progressive and associated with ascites. It is concluded that in the rat the morphological sequelae of long term cholestasis induced by either cannulation and obstruction or ligation of bile ducts are similar and are accompanied by cirrhosis. The advantages of this experimental model for the study of human cirrhosis are discussed.     

Effects of Immunization with B. Macacae on induced Periodontitis-Preliminary Findings

This preliminary study examined the effects of immunization with Bacteroides macacae. the monkey equivalent of the human species of B. gingivalis on ligature-induced periodontitis. During a 12 week immunization period, 8 out of the 12 Macacae fasicularis monkeys were immunized weekly with B. macacae washed cells and 4 were sham-immunized with saline. At the same time, all were scaled and pumiced weekly to establish gingival health. Following this period, the mandibular first molars were ligated in 8 out of the 12 monkeys to induce periodontitis. The immunized, ligated experimental group, the ligated, sham-immunized control group, and the immunized, non-ligated control group were then followed for a 6 months ligation period while plaque was allowed to accumulate. Gingival indices, attachment levels, pocket depths, plaque indices, radiographs, serum and crevicular fluid antibodies and subgingival bacteria were assessed. Immunization led to elevated antibody levels to B. macacae while ligation increased plaque, gingival inflammation, and bone loss. Following the 6 month ligation period, B. macacae comprised 1.7% of the cultivable flora in the immunized, non-ligated monkeys, 2.1% in the immunized, ligated monkeys, and 5.6% in the sham-immunized, ligated monkeys. Similar differences between the immunized, ligated and the sham-immunized, ligated groups were not seen for B. intermedius. nor B. melaninogenicus. These results suggest a heightened humoral response to B. gingivalis reduces subgingival re-colonization by this organism and modulates the course of ligature-induced periodontitis.     

Experimental peripheral neuropathy decreases the dose of substance P required to increase excitatory amino acid release in the CSF of the rat spinal cord.

Partial ligation of the sciatic nerve of rats produces hyperalgesia similar to that seen in humans following nerve injury. In this study, we used microdialysis of the spinal cord cerebral spinal fluid (CSF) to test the hypothesis that hyperalgesia is due to an enhanced release of excitatory amino acids (EAA) in response to substance P (SP). Intrathecal SP caused release of aspartate and glutamate in the CSF of rats with partial sciatic ligation at a dose of SP that did not cause release in sham operated animals. Neonatal capsaicin pretreatment blocked SP-induced EAA release in both sham and sciatic ligated animals. Release of EAAs in ligated animals was not significantly different from release in sham-operated animals following higher doses of SP or chemical nociceptive stimulation. These results demonstrate a partial sciatic ligation-induced decrease in the dose of SP required to initiate EAA release in the CSF of the spinal cord, a change which could play an important role in hyperalgesia.     

Calf ligated intestinal segment test to detect enterotoxigenic Escherichia coli.

The ligated intestinal segment test in the young calf was utilized to establish the enterotoxigenicity of approximately 600 Escherichia coli isolates obtained from fecal specimens intestinal contents of calves with diarrheal disease. One hundred and fifty isolates were routinely tested in a single calf. There was little problem with false-positive reactions. False-negative reactions normally occurred only if the isolate was tested in the posterior 3 m of the small intestine. The ligated small intestine of the calf was distended by E. coli isolates of bovine, porcine, and human origin. Use of the calf ligated intestinal segment test is recommended to determine the enterotoxigenicity of E. coli isolates of bovine origin.     

Contractile properties during development of hypertrophy of the smooth muscle in the rat portal vein

Structural and mechanical alterations during hypertrophy of the rat portal vein were investigated. Growth of the vessel was induced by a partial ligature of the vessel causing an increased transmural pressure. Vessel segments from animals kept with ligature for 1, 3, 5 and 7 days, were compared with vessels from sham-operated animals. Maximal active force and vessel cross-sectional area increased with time in the ligated group. On day 7, force and cross-sectional area at the optimal length, were markedly increased in the ligated group (21.1 +/- 1.0 mN, 0.55 +/- 0.04 mm2, n = 9) compared with the control vessels (11.7 +/- 1.0 mN, 0.30 +/- 0.02 mm2, n = 7). Light and electron microscopy of preparations fixed at optimal length showed that the amount of smooth muscle and the cross-sectional area of cell profiles were almost doubled in the ligated group on day 7, consistent with hypertrophy of the smooth muscle. The force per smooth muscle cell area was similar in the two groups (ligated: 132 +/- 15; control: 145 +/- 16 mN mm-2, n = 4-5). The maximal shortening velocity was significantly lower in the hypertrophied group (ligated: 0.28 +/- 0.02; control: 0.41 +/- 0.01 optimal length s-1, n = 6). In chemically skinned preparations, activated by maximal thiophosphorylation of the myosin light chains, force was higher in the ligated group compared to the controls but no difference in maximal shortening velocity was observed. In conclusion, the increased transmural pressure is associated with a rapid increase in the amount of smooth muscle in the portal vein. The mechanical data show that after 7 days the force generating ability of the contractile system has increased in proportion to the smooth muscle cell mass. The unaltered maximal shortening velocity in the skinned hypertrophied preparations suggests that the kinetic properties of the maximally activated contractile system are unaltered. The decreased maximal shortening velocity in the intact hypertrophied preparations may reflect alterations in the excitation-contraction coupling.     

The organization of the seminiferous epithelium in the mouse testis following ligation of the efferent ductules. A light microscopic study

In order to more fully assess and determine the relationship between the developing germ cells and the Sertoli cell epithelium, efferent ductules of Swiss albino mice testes were ligated and the effects observed. This method stretched the walls of the seminiferous tubules and thus reduced the stratification and complexity of the epithelium. At 48 hours postoperation, the testes were removed in a manner to prevent the escape of accumulated fluid. A marked size difference between the ligated and sham-operated testes was noted. Tissues were fixed in 3% phosphate buffered glutaraldehyde solution and later prepared for sectioning and examination by the light microscope. The seminiferous tubules in the ligated testes had relatively large lumens which contained spermatozoa, and the tubule epithelium was reduced in height. The various stages of cellular associations of the cycle of the epithelium were retained. Defined aggregations of germ cells grouped in specific association with the Sertoli cell elements were observed. The epithelium assumed the form of a series of parallel ridges at right angles to the tubules. Longitudinal sections of the tubules revealed pillarlike epithelial profiles. Each pillar consisted of Sertoli cell cytoplasm together with 2 generations of spermatids. The older generation of spermatids was embedded within the Sertoli cell and the younger generation along the sides. It is suggested that each generation within a ridge constitutes a single clone. The cytoplasmic bridges joining the spermatids and their attachments to the Sertoli cells are thought to determine the organization and structure of the rid ges. Several illustrations show the histological details of the structure.     

NaCl solution ingestion in genetic (SHR) and aortic-ligation hypertension.

Two types of rats with hypertension were investigated to clarify the relation between the free ingestion of NaCl solutions (0.5–3.0% NaCl) and established genetic (SHR Okamoto strain) and renovascular (aortic ligation) hypertension. The acceptability of NaCl was measured by rehydration drinking of a single solution in a 1-hr period. The preference for NaCl was measured by allowing continuous access to both a single NaCl solution and water. Except at the ends of the Nacl concentration range, NaCl solutions were both more accepted and preferred by the SHR strain in comparison to the Wistar-Kyoto (WKY) controls. Water turnover was not different between SHR and WKY animals. In the chronichypertension phase of aortic-ligation, there was no difference in NaCl acceptability between ligated and sham-operated groups. The middle range of NaCl concentrations was nonpreferred by ligated animals relative to the sham-operated group. Water turnover increased markedly for several days in the post-operative period for ligated animals and then descended. However, the turnover remained greater for ligated rats compared to their sham-operated controls. A chronically elevated blood pressure, then, does not in itself appear to produce an increase in NaCl ingestion. In fact, the present results together with other studies made during the chronic phase of renovascular hypertension indicate a relative lack of preference for NaCl solutions. The greater NaCl solution acceptance and preference of the SHR strain cannot be related to the etiology of genetic hypertension at present.