Biomedical subjects

C C Tai

Publications and source records attributed to C C Tai.

At least 19 recordsLinked to original sources

PubMed2006

Five- to 12-year follow-up of a hydroxyapatite-coated, cementless total knee replacement in young, active patients.

We carried out a prospective study of 118 hydroxyapatite-coated, cementless total knee replacements in patients who were </= 55 years of age and who had primary (92; 78%) or post-traumatic (26; 22%) osteoarthritis. The mean period of follow-up was 7.9 years (5 to 12.5). The Knee Society clinical scores improved from a pre-operative mean of 98 (0 to 137) to a mean of 185 (135 to 200) at five years, and 173 (137 to 200) at ten years. There were two revisions of the tibial component because of aseptic loosening, and one case of polyethylene wear requiring further surgery. There was no osteolysis or progressive radiological loosening of any other component. At 12 years, the overall rate of implant survival was 97.5% (excluding exchange of spacer) and 92.1% (including exchange of spacer). Cementless total knee replacement can achieve excellent long-term results in young, active patients with osteoarthritis. In contrast to total hip replacement, polyethylene wear, osteolysis and loosening of the prosthesis were not major problems for these patients, although it is possible that this observation could change with longer periods of follow-up.

Adult↗

PubMed2005

Intra-operative assessment of excision margins using breast imprint and scrape cytology.

Local recurrence in breast cancer surgery is related to the completeness of excision. Histological analysis of excision margins is time consuming and impractical for use intra-operatively. Our group evaluated breast imprint and scrape cytology (ISC) for the assessment of excision margins in a feasibility study in 1993-4, with 10 year clinical follow-up. Twenty-six consecutive women undergoing 27 wide local excisions for breast cancer had excision margins prospectively assessed with intra-operative ISC blinded to histology. All ISC results were ready (range 22-30 min) before surgery was completed. ISC agreed with histology in 21/27 (=78%) and disagreed in 6/27 (=22%) of the cases. In two cases with local recurrence, histology was positive in one case, whereas ISC margins were positive in both. Intra-operative ISC is reliable and could help the surgeon to excise more tissue to prevent a second (re-excision) operation. ISC margins may predict clinical outcome, although a larger interventional follow-up study is required.

Adult↗

PubMed2005

Management of suspected scaphoid fractures in accident and emergency departments--time for new guidelines.

INTRODUCTION: The objectives of this work were to assess the clinical knowledge of clinicians in the accident and emergency (A&E) departments in England & Wales and evaluate the current trend for the acute management of radiologically normal, but clinically suspected, fractures of the scaphoid. SUBJECTS AND METHODS: We conducted a telephone survey on 146 A&E senior house officers (SHOs) in 50 different hospitals. This survey assessed the clinicians' experience, their clinical and radiological diagnostic methods, and their initial treatment of suspected scaphoid fractures. RESULTS: The majority (55.8%) of SHOs performed only one clinical test to diagnose suspected scaphoid fractures. Overall, 41% were unable to cite the number of the radiographic views taken and only 10% of departments have direct access to further radiological investigation. There is wide variation in the early treatment of this injury, with the scaphoid cast used most commonly (46%). The majority of SHOs (89%) were unable to describe the features of immobilisation. The mean follow-up period was 10 days, and 53% of cases were followed-up by the senior staff in A&E. Of SHOs, 54% were not aware of any local guidelines for the management of suspected scaphoid fractures in their departments, and 92% were not aware of the existence of the 1992 British Association for Accident and Emergency Medicine (BAEM) guidelines. CONCLUSIONS: The clinical knowledge and the management of suspected scaphoid fractures in A&E are unsatisfactory. We, therefore, suggest that the dissemination of up-to-date guidelines could help to educate clinicians to provide better care to the patients.

Clinical Competence↗

PubMed2003

Methicillin-resistant Staphylococcus aureus in orthopaedic surgery.

We prospectively studied the incidence of methicillin-resistant Staphylococcus aureus (MRSA) colonisation and infection, the patterns and types of operation associated with MRSA acquisition in an orthopaedic and trauma unit in London, UK. Over the 12-month study period from January to December 2000, we found that 1.6% of the total admission was diagnosed to be either MRSA infected or colonised, with an average of three new MRSA cases detected per month. A significant proportion of patients (23%) were diagnosed within the first 48h of admission. Both hip joint surgery, especially emergency procedures for femoral neck fractures, and the presence of a wound presented higher risk of infection. The Intensive Care Unit (ICU) did not appear to be a significant source for intra-hospital dissemination among the orthopaedic patients. MRSA infection or colonisation contributed to an increased length of hospital stay; 88 days compared to 11 days on average for non-MRSA patients; 41% of the positive patients still carried MRSA on discharge. Our data show the importance of diagnosing MRSA in orthopaedic surgery and emphasises that understanding its epidemiology will be crucial to secure a decrease in the incidence of MRSA. Hand hygiene, patient screening, careful surveillance of infections and the prompt implementation of isolation policies, are essential components of control.

Adult↗

PubMed2003

Acetabular labrum and its tears.

Groin pain is a major cause of morbidity in athletes. Only in the last decade have acetabular labrum tears been recognised as a possible diagnosis. Awareness of this condition is important for appropriate management. The basic science and pathological and clinical features of acetabular labrum tears are reviewed, and diagnostic and treatment options are presented.

Acetabulum↗

PubMed2002

Antibiotic prophylaxis in surgery of the intervertebral disc. A comparison between gentamicin and cefuroxime.

Antibiotics are often administrated prophylactically in spinal procedures to reduce the risk of infection of the disc space. It is still not known which antibiotics are able to penetrate the intervertebral disc effectively. In a prospective, randomised, double-blind clinical study, we examined the penetration of the intervertebral discs of two commonly used antibiotics, cefuroxime and gentamicin. The patients, randomised into two groups, received either 1.5 g of cefuroxime or 5 mg/kg of gentamicin prophylactically two hours before their intervertebral discs were removed. A specimen of blood, from which serum antibiotic levels were determined, was obtained at the time of discectomy. Therapeutic levels of antibiotic were detectable in the intervertebral discs of the ten patients who received gentamicin. Only two of the ten patients (20%) who received cefuroxime had a quantifiable level of antibiotic in their discs although therapeutic serum levels of cefuroxime were found in all ten patients. Our results show that cefuroxime does not diffuse into human intervertebral discs as readily as gentamicin. It is possible that the charge due to ionisable groups on the antibiotics can influence the penetration of the antibiotics. We therefore recommend the use of gentamicin in a single prophylactic dose for all spinal procedures in order to reduce the risk of discitis.

Adult↗

PubMed2000

Tuning metal-to-metal charge transfer of mixed-valence complexes containing ferrocenylpyridine and rutheniumammines via solvent donicity and substituent effects.

A homogeneous series of heterobimetallic complexes of [R-Fc(4-py)Ru(NH3)5](PF6)2 (R = H, Et, Br, acetyl; Fc(4-py) = 4-ferrocenylpyridine) have been prepared and characterized. The mixed-valence species generated in situ using ferrocenium hexafluorophosphate as the oxidant show class II behavior, and the oxidized sites are ruthenium centered. deltaE(1/2), E(1/2)(Fe(III)/Fe(II)) - E(1/2)(Ru(III)/Ru(II)), an upper limit for deltaGo that is an energetic difference between the donor and acceptor sites, changes sharply and linearly with Gutmann solvent donor number (DN) and Hammett substituent constants (sigma). The solvent-dependent and substituent-dependent intervalence transfer bands were found to vary almost exclusively with deltaE(1/2). The activation energy for the optical electron transfer versus deltaE(1/2) plot yields a common nuclear reorganization energy (lambda) of 0.74 +/- 0.04 eV for this series. The equation that allows one to incorporate the effect of both solvent donicity and substituents on optical electron transfer is Eop = lambda + deltaGo, where deltaGo = (deltaGo)intrinsic + (deltaGo)solvent donicity + (deltaGo)substituent effect (deltaGo )intinnsic with a numerical value of 0.083 +/- 0.045 eV was obtained from the intercept of the deltaE(1/2) of [H-Fc(4-py)Ru(NH3)5]2+,3+,4+ versus DN plot. (deltaGo)solvent donicity was obtained from the average slopes of the deltaE(1/2) of [R-Fc-(4-py)Ru(NH3)5]2+,3+,4+ versus DN plot, and (deltaGo)substituent effect was obtained from the average slopes of the corresponding deltaE(1/2) versus sigma plot. The empirical equation allows one to finely tune Eop of this series to Eop = 0.82 + 0.019(DN) + 0.44sigma eV at 298 K, and the discrepancy between the calculated and experimental data is less than 6%.

Journal Article↗

PubMed2000

Neocortical neurons lacking the protein-tyrosine kinase B receptor display abnormal differentiation and process elongation in vitro and in vivo.

The spatial and temporal expression of the protein-tyrosine kinase B (TrkB) receptor and its ligands has been correlated with the development of the neocortex. Activation of the receptor has been associated with neocortical neuronal survival, differentiation, connectivity and neurotransmitter release. Although such findings suggest an important role for TrkB signaling in corticogenesis, conclusive evidence from targeted gene deletion ("knockout"; TrkB -/-) mice has been limited, due in part to the neonatal lethality of most of these mutant mice and the confounding variables associated with the poor health of those few surviving slightly longer postnatally. In the present study, the effects of TrkB signaling on the survival, differentiation and integration of neocortical neurons was directly investigated in vitro and in vivo. First, we conducted a neuron-specific immunocytochemical analysis of TrkB -/- mice to determine whether early cortical structure and patterns of histogenesis were normal or perturbed. We then employed in vitro and in vivo approaches to extend the life of TrkB -/- neocortical neurons beyond the period possible in TrkB -/- mutant mice themselves: (i) dissociated cell culture to directly compare the developmental potential of TrkB -/-, +/- and +/+ neurons; and (ii) neural transplantation into homochronic wild-type recipients to investigate the cell-autonomous effects of the receptor knockout on the differentiation, growth and integration of neocortical neurons. These latter experiments allowed, for the first time, study of the survival and differentiation potential of TrkB -/- neocortical neurons beyond the initial stages of corticogenesis. Direct comparison of brains of TrkB -/-, +/- and +/+ littermates immunocytochemically labeled with antibodies to microtubule-associated protein-2, neurofilament and beta-tubulin III revealed subtle anatomical anomalies in the mutant mice. These anomalies include abnormally diffuse microtubule-associated protein-2 positive neurons just dorsal to the corpus callosum, and heterotopic aggregations of postmitotic neurons in the subventricular zones of the ganglionic eminences, both suggesting delayed neuronal migration and differentiation. Cell culture experiments revealed substantially reduced survival by TrkB -/- neocortical neurons, and a significant reduction in neurite outgrowth by surviving TrkB -/- neurons. In experiments where prelabeled embryonic or neonatal TrkB -/- neocortical neurons were transplanted into the cerebral cortices of neonatal wild-type recipients, a similar quantitatively significant defect in the formation of dendrites, as well as reduced integration of TrkB -/- neocortical neurons, was also evident. These findings demonstrate cell-autonomous abnormalities in the development of neocortical neurons from TrkB -/- mice, and the subtle, but potentially critical, role of protein-tyrosine kinase B signaling in neocortical neuronal survival, differentiation and connectivity.

Animals↗

PubMed2000

Prospective analysis of secondary alveolar bone grafting using computed tomography.

PURPOSE: This study radiographically evaluated the quantity and quality of secondary alveolar bone grafts from the anterior iliac crest to maxillary alveolar clefts in cleft lip and palate patients with the use of computed tomography. PATIENTS AND METHODS: A 1-year prospective study was conducted by using 14 unilateral and bilateral cleft lip and palate patients. Axial and coronal computed tomography (CT) scans were obtained during the immediate postoperative phase and at 1-year follow-up. RESULTS: This study showed that the average alveolar cleft requires a bone graft volume ranging from 0.9 to 3.6 cm3, with a mean volume of 2.10 cm3. The percentage of bone loss derived from the linear dimensional changes to the alveolar bone graft between the immediate postoperative and follow-up CT scans were as follows: 17.9% in maximal bone height, 29.9% in maximal anteroposterior bone width, and 13.7% in maximal transverse width. As compared with the linear measurements, the volumetric analysis showed a disproportional amount of volume loss equaling 43.7% and 42.5% in the coronal and axial studies, respectively. This showed a total average volume loss of 43.1% at approximately 1 year after the secondary alveolar cleft repair. However, as the canine tooth erupts through the bone graft, it can account for up to 53.4% of the total average volume loss. All 14 patients (17 clefts) showed bone bridging between the alveolar cleft radiographically, with good incorporation and maturation of the bone graft, and no recurrence of the oronasal fistula. CONCLUSION: The CT scan is a valuable radiographic imaging modality to assess and follow the clinical outcome of secondary alveolar bone grafting.

Adolescent↗

PubMed1999

Effects of vasopressin on portal-systemic collaterals in portal hypertensive rats: role of nitric oxide and prostaglandin.

This study investigated the effect of vasopressin on portal-systemic collaterals in portal hypertensive rats and the influence of nitric oxide (NO) and prostaglandin on the responsiveness of collateral vessels to vasopressin. The vascular responsiveness to graded concentrations of vasopressin was tested with or without the incubation of n(omega)-nitro-L-arginine (NNA) (100 micromol/L) and/or indomethacin (10 micromol/L) in perfused collateral vascular beds of rats with portal hypertension induced by partial portal vein ligation. In addition, concentration-response curves to vasopressin with incubation of a vasopressin V(1) receptor antagonist d(CH(2))(5)Tyr(Me) arginine vasopressin and concentration-response curves to a V(2) receptor agonist 1-desamino-8-D-arginine vasopressin were performed. Vasopressin significantly increased the perfusion pressure of collaterals, and this effect was suppressed by the addition of the V(1) receptor antagonist. Perfusion with the V(2) receptor agonist had no effect on the collaterals. Incubation with NNA, indomethacin, or both significantly potentiated the response of collaterals to vasopressin. In addition, the pressor response to vasopressin in the combination group was significantly higher than that in the NNA-alone group. The results show that vasopressin produces a direct vasoconstrictive effect on the portal-systemic collaterals of portal hypertensive rats. This effect is mediated by the vasopressin V(1,) but not V(2), receptors. The attenuation of the response to vasopressin by NO and prostaglandin suggest a function role of both mediators in the regulation of the portal-systemic collateral circulation in portal hypertensive rats.

Animals↗

PubMed1999

Enhanced decomposition of NO on the alkalized PdO/Al2O3 catalyst.

Experimentally, decomposition of NO on the alkalized Pd/Al2O3 catalyst is remarkably enhanced at 825-1000 K. The enhancement in N2 yield may be due to the additional basic sites on the alkalized catalyst that can trap NO molecules. However, at T > 1000 K, due to the fact that the absorbed oxygen in subsurface or bulk of Pd was involved in the formation and desorption of oxygen molecules, yield of oxygen was enhanced.

Adsorption↗

PubMed1999

Evidence against a role for endotoxin in the hyperdynamic circulation of rats with prehepatic portal hypertension.

BACKGROUND/AIMS: Excessive formation of nitric oxide may mediate the generalized vasorelaxation and hyporesponsiveness to vasoconstrictors observed in portal hypertensive states. Endotoxin, released from the bowel and detoxified by the liver, could stimulate inducible nitric oxide synthase directly or indirectly via the cytokine cascade. This study investigated the effect of chronic intraperitoneal injection of polymyxin B, a neutralizing antagonist of endotoxin, on the hemodynamics of partially portal vein-ligated (PVL) rats. METHODS: Concomitantly with endotoxin (600 EU) and dactinomycin (80 microg), polymyxin B (0.1 mg) or normal saline (N/S) was administered via an intraperitoneal route to male Sprague-Dawley rats. Twenty-four hours later, mean arterial pressure was determined. In PVL rats polymyxin B (0.1 mg in 5 cc N/S) or N/S was given intraperitoneally twice daily from 2 days prior to operation until 5 days (short-term) or 14 days (long-term) after the operation. Long-term polymyxin B- or N/S-treated sham-operated rats were included as controls. Hemodynamic studies with a thermodilution technique were performed at the end of treatment. Blood samples were collected from another series of PVL rats with long-term treatment to determine plasma levels of endotoxin and tumor necrosis factor-alpha. Plasma levels of endotoxin and tumor necrosis factor-alpha were measured by Limulus assay and the ELISA method, respectively. RESULTS: With the dosage of 0.1 mg polymyxin B, hypotension in rats subjected to endotoxin and dactinomycin administration could be corrected (polymyxin B vs. placebo: 130.0+/-7.7 vs. 108.8+/-6.7 mm Hg, p<0.05). However, long-term or short-term treatment with the same dosage of polymyxin B failed to ameliorate the hyperdynamic circulation of PVL rats. In addition, long-term treatment with polymyxin B did not change systemic and portal hemodynamics in sham-operated rats. Plasma levels of endotoxin and tumor necrosis factor-alpha were comparable in PVL rats treated with long-term polymyxin B or N/S (p>0.05). CONCLUSIONS: Our findings do not support the role of endotoxin in the hyperdynamic circulation of PVL rats.

Animals↗

PubMed1999

Delayed irradiation effects on nasal epithelium in patients with nasopharyngeal carcinoma. An ultrastructural study.

The ostiomeatal complex is responsible for the clearance of most sinus secretions. To evaluate the delayed effects of irradiation. this study examined the infundibulum mucosa of 10 patients who developed sinusitis after receiving radiotherapy for nasopharyngeal carcinoma (NPC). Pathologic findings under the light microscope revealed an increased deposition of dense collagenous fibers in the lamina propria. The epithelial cells also transformed into a stratified arrangement and showed gradual reduction of cytoplasmic volume. Ultrastructural observations detected areas of ciliary loss, intercellular and intracellular vacuolation, and ciliary dysmorphism. Most of these pathologic findings were observed even in a patient 23 years after irradiation. The results presented herein suggest that radiotherapy may cause long-term damage to the nasal epithelium that may be responsible for the prolonged sinusitis of irradiated NPC patients.

Adult↗

PubMed1998

Chronic administration of octreotide ameliorates portal hypertension and portal hypertensive gastropathy in rats with cirrhosis.

1. Portal hypertension and hyperdynamic circulation have been postulated to play a role in the pathogenesis of portal hypertensive gastropathy. Administration of octreotide to portal hypertensive rats has been shown to reduce portal pressure and ameliorate hyperdynamic circulation. 2. This study investigated the effects of chronic administration of octreotide on systemic and portal haemodynamics and the development of portal hypertensive gastropathy in carbon tetrachloride-induced cirrhotic rats. 3. After 12 weeks of carbon tetrachloride induction, cirrhotic rats were randomly assigned to receive either placebo (5% dextrose in water) or octreotide (65 micrograms/kg in 5% dextrose in water) subcutaneously twice daily for 10 days. Haemodynamic studies with a thermodilution technique and gastric morphometric analyses were performed at 10 days after treatment. 4. In cirrhotic rats, octreotide treatment induced a significant increase in systemic vascular resistance (2.7 +/- 0.2 versus 3.4 +/- 0.2 mmHg/ml.min-1.100 g-1, P < 0.05) and decrease in portal pressure (12.5 +/- 1.2 versus 9.9 +/- 0.5 mmHg, P < 0.05) compared with placebo-treated rats. In addition, octreotide treatment significantly reduced the mean cross-sectional area of gastric mucosal vessels (2290 +/- 145 versus 1810 +/- 101 micron 2, P < 0.05). 5. This study shows that chronic octreotide treatment ameliorates the development of portal hypertensive gastropathy in cirrhotic rats. The effect of octreotide on portal hypertensive gastropathy may, at least partly, be due to the alleviation of portal hypertension and hyperdynamic circulation.

Animals↗

PubMed1998

Aminoguanidine ameliorates splanchnic hyposensitivity to glypressin in a haemorrhage-transfused rat model of portal hypertension.

1. Hyposensitivity to vasopressin is a well-documented phenomenon in animals with portal hypertension and patients with cirrhosis subjected to haemorrhage. Excessive formation of nitric oxide is at least partly responsible for the vascular hyporesponsiveness to vasoconstrictors observed in experimental portal hypertension or in rats with haemorrhagic shock. This study investigated whether addition of aminoguanidine, a preferential inducible nitric oxide synthase inhibitor, to glypressin (a long-acting vasopressin analogue) could enhance its portal hypotensive effect in portal-hypertensive rats with bleeding.2. Portal hypertension was induced by partial portal vein ligation. Fourteen days after operation, systemic and portal haemodynamics were measured in stable or bleeding portal vein-ligated rats receiving intravenous glypressin (0.07 mg/kg) or aminoguanidine (70 mg/kg) followed by glypressin infusion. In rats with a hypotensive haemorrhage, 4.5 ml of blood was withdrawn and 50% of the withdrawn blood was reinfused before the administration of glypressin or aminoguanidine.3. Glypressin resulted in a significantly greater decrease in portal pressure in portal vein-ligated rats without bleeding than in those with bleeding (P<0.001). In contrast, glypressin induced similar changes in mean arterial pressure between the two groups (P>0.05). The addition of aminoguanidine significantly potentiated the portal-hypotensive effect of glypressin in bleeding portal vein-ligated rats (P<0.005) without an effect on the changes in mean arterial pressure induced by glypressin infusion (P>0.05).4. Splanchnic hyposensitivity to glypressin exists in a haemorrhage-transfused rat model of portal hypertension. This hyposensitivity can be ameliorated by the administration of aminoguanidine.

Animals↗

PubMed1997

Aminoguanidine corrects hyperdynamic circulation without ameliorating portal hypertension and portal hypertensive gastropathy in anesthetized portal hypertensive rats.

BACKGROUND/AIMS: Portal hypertension and hyperdynamic circulation (i.e. generalized vasodilation and increased cardiac output and regional organ blood flows) may play an important role in the development of portal hypertensive gastropathy. This study investigated the effect of chronic administration of aminoguanidine, a selective inducible nitric oxide synthase inhibitor, to portal hypertensive rats on hemodynamics and the development of portal hypertensive gastropathy. METHODS: Partial portal vein-ligated or sham-operated rats were randomly assigned to receive either placebo (distilled water) or aminoguanidine (approximately 100 mg/kg per day subcutaneously) for 2 days prior to and 14 days. Hemodynamic studies with a thermodilution technique and gastric morphometric analysis were performed at 14 days after the operation. RESULTS: In rats given placebo, portal vein-ligated rats had a significantly lower mean arterial pressure and systemic vascular resistance associated with a significantly higher cardiac index and portal pressure than sham-operated rats (p<0.05). In portal vein-ligated rats aminoguanidine induced a significant increase in mean arterial pressure and systemic vascular resistance accompanied by a significant decrease in cardiac index (p<0.05) without changes in portal pressure (p>0.05). Despite persistence of portal hypertension, the aminoguanidine-treated portal vein-ligated rats had similar mean arterial pressure, cardiac index, and systemic vascular resistance as seen in placebo-treated sham-operated rats. The mean cross-sectional area of gastric mucosal vessels was significantly higher in placebo-treated portal vein-ligated than in placebo-treated sham-operated rats (p<0.05). Treatment with aminoguanidine did not induce changes in the mean cross-sectional area of gastric mucosal vessels in either portal vein-ligated or sham-operated rats (p>0.05). CONCLUSIONS: The results show that in portal hypertensive rats long-term aminoguanidine therapy corrects the hyperdynamic circulation without inducing changes in portal pressure and ameliorating the development of portal hypertensive gastropathy. This study suggests that, instead of correcting hyperdynamic circulation, treatment of portal hypertensive gastropathy should be aimed at reducing portal pressure.

Animals↗

PubMed1997

Hemodynamic studies and esophageal morphometric analyses in portal hypertensive rats with left adrenal vein ligation.

BACKGROUND: Despite many attempts to create esophageal varices in experimental animals, most of them have failed. This study investigated whether rats with partial portal vein ligation (PVL) and left adrenal vein ligation (LAL) develop hyperdynamic circulation and dilated esophageal submucosal veins as compared with sham-operated (Sham) plus LAL rats. METHODS: Two series of experiments were performed to measure (a) systemic and portal hemodynamics and (b) the cross-sectional area of esophageal submucosal veins in Sham, PVL, Sham plus LAL, and PVL plus LAL rats. Hemodynamic studies with a thermodilution technique and esophageal morphometric analyses were performed 14 days after the operation. RESULTS: PVL rats with or without LAL had a significantly lower mean arterial pressure and systemic vascular resistance accompanied by a significantly cardiac index and portal pressure than Sham rats with or without LAL (P < 0.05). LAL did not induce changes in mean arterial pressure, cardiac index, systemic vascular resistance, hear rate, or portal pressure in either Sham or PVL rats (P > 0.05). The mean cross-sectional area of esophageal submucosal veins in PVL rats with LAL (7340 +/- 833 microns2) was significantly larger than that in Sham rats with LAL (4236 +/- 556 microns2; P < 0.05). There was no significant difference in the mean cross-sectional area of esophageal submucosal veins between PVL and Sham rats without LAL. CONCLUSIONS: PVL rats with LAL developed hyperdynamic circulation similar to PVL rats without LAL. In addition, PVL plus LAL rats had larger esophageal submucosal veins than Sham plus LAL rats. This study shows that the esophageal submucosal veins of the 14-day partially portal vein-ligated rats with LAL resemble the structural abnormalities observed in human esophageal varices, suggesting that this model could be useful to investigate this entity.

Adrenal Glands↗

PubMed1997

Hyperdynamic circulation of cirrhotic rats: role of substance P and its relationship to nitric oxide.

BACKGROUND: It has been suggested that excessive formation of nitric oxide (NO) is responsible for the hyperdynamic circulation observed in portal hypertension. Substance P is a neuropeptide partly cleared by the liver and causes vasodilatation through the activation of the endothelial NO pathway. However, there are no previously published data concerning the plasma level of substance P in cirrhotic rats and its relationship to NO. METHODS: Plasma concentrations of substance P and nitrate/nitrite (an index of NO production) were determined in control rats and cirrhotic rats with or without ascites using an enzyme-linked immununosorbent assay and a colorimetric assay, respectively. In addition, systemic and portal hemodynamics were evaluated by a thermodilution technique and catheterization. RESULTS: Cirrhotic rats with and without ascites had a lower systemic vascular resistance (2.6 +/- 0.2 and 3.9 +/- 0.4 mmHg ml(-1) x min x 100 g body weight, respectively) and higher portal pressure (14.6 +/- 0.6 and 11.3 +/- 1.8 mmHg) than control rats (6.5 +/- 0.3 mmHg x ml(-1) x min x 100 g BW and 6.8 +/- 0.2 mmHg, respectively, P < 0.05), and cirrhotic rats with ascites had the lowest systemic vascular resistance. Plasma levels of nitrate/nitrite progressively increased in relation to the severity of liver dysfunction (control rats, 2.7 +/- 0.5 nmol/ml; cirrhotic rats without ascites, 5.6 +/- 1.3 nmol/ml; cirrhotic rats with ascites, 8.3 +/- 2.2 nmol/ml; P < 0.05). Cirrhotic rats with ascites displayed higher plasma values of substance P (57.7 +/- 5.9 pg/ml) than cirrhotic rats without ascites (37.9 +/- 3.1 pg/ml, P < 0.05) and control rats (30.1 +/- 1.0 pg/ml, P < 0.05). There was no significant difference in plasma substance P values between control rats and cirrhotic rats without ascites (P > 0.05). No correlation was found between plasma levels of substance P and nitrate/nitrite (r = 0.318, P > 0.05). CONCLUSIONS: Excessive formation of NO may be responsible, at least partly, for the hemodynamic derangements in cirrhosis. Although substance P may not participate in the initiation of a hyperdynamic circulation in cirrhosis, it may contribute to the maintenance of the hyperdynamic circulation observed in cirrhotic rats with ascites.

Analysis of Variance↗