Biomedical subjects
Publications and source records attributed to Y T Huang.
Mink lung cells were more sensitive than the commonly used MDCK or pRhMK cells for rapid detection of influenza virus A from clinical specimens. Mixed Mv1Lu and A549 cells in a single shell vial were synergistic for detection of influenza virus A and were as sensitive as individual cells for detection of other respiratory viruses.
The Zta protein is a key transactivator involved in initiating the Epstein-Barr virus (EBV) lytic cascade. In addition to transactivating many viral genes, Zta has the capacity to influence host cellular signals by binding to promoter regions or by interacting with several important cellular factors. Based on the observation that tyrosine kinases play central roles in determining the fate of cells, a kinase display assay was used to investigate whether cells expressing Zta have an altered pattern of kinase expression. The assay revealed that TRK-related tyrosine kinase (TKT) is expressed at significant levels in Zta transfectants but not in control cells. Additional evidence was obtained from Northern and Western blotting. Importantly, the upregulation of phosphorylated TKT and TKT downstream effector matrix metalloproteinase 1 in Zta transfectants hinted that TKT might initiate a signaling cascade in Zta-expressing cells. In addition, deletion analysis of the Zta protein revealed that the transactivation and dimerization domains were both essential for the upregulation of TKT transcription. Moreover, correlation of expression levels of Zta and TKT transcripts in nasopharyngeal carcinoma biopsy specimens was clearly demonstrated by quantitative PCR (Q-PCR), which provides the first evidence for an effect of Zta on cellular gene expression in vivo. These findings offer insight into the virus-cell interactions and may help us elucidate the role of EBV in tumorigenesis.
The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) can induce expression of many immediate-early genes, such as c-fos and c-jun. In this study, TPA increased c-fos mRNA, cellular cyclic AMP, and protein kinase A (PKA) activity in the first 30 min with similar inductive time courses. Treatment of NIH 3T3 cells with N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoline sulfonamide (H-89), a PKA specific inhibitor, suppressed TPA induction of PKA activity and c-fos mRNA in a concentration-dependent manner, but did not inhibit serum-induced transcription. H-89 did not inhibit TPA and serum induction of c-jun mRNA. H-89 interfered with TPA-stimulated serum-responsive element-binding activity in a concentration-dependent manner, but did not inhibit TPA-induced mitogen-activated protein kinase 1/2 activity or Elk-1 phosphorylation. TPA stimulation of a c-fos promoter reporter construct was inhibited by overexpression of the dominant negative regulatory protein of PKA. In deletion studies, the H-89 inhibitory element was found to be localized between -563 and -379 in the c-fos promoter region. These results suggest that H-89 will be very useful for investigating the molecular mechanism of TPA induction of c-fos.
Simian immunodeficiency virus (SIV) infection of primates provides an important model for infection of humans by HIV. Since mucosal epithelium is likely to be an important portal of entry, we decided to study aspects of the interaction of SIV with epithelial cells. SIV was shown to produce virus efficiently in polarized epithelial cells (Vero C1008) transfected with SIVmac239 proviral DNA. The virus titer in the epithelial cell culture fluid reached 10(3) TCID50/ml at day 3 posttransfection. Initially after transfected epithelial cells were plated on a permeable membrane, virus budded at both the apical and the basolateral domains. However, after the cells formed a tight monolayer, 95-100% of the virus particles budded basolaterally, as assessed by release of p27 antigen into the fluid above and below the monolayer. This finding was confirmed by electron microscopy, which showed that the mature virus budded basolaterally in polarized cells. After introduction of the CD4 gene into Vero cells by a retrovirus vector, polarizable cells were able to be infected by cell-free SIVmac239 virus. The virus titer reached 10(4) TCID50/ml in culture fluid and virions also budded basolaterally, the same as the virus from transfected cells. Two viruses (SIVmac1A11 and SIVmac251) that contain truncated TMgp28 instead of TMgp41 also budded basolaterally. Furthermore, we found that HIV-1 with full-length or truncated TMgp41 also budded basolaterally.
In vivo administration of bacterial superantigen staphylococcal enterotoxin B (SEB) to BALB/c mice led to thymus atrophy resulting from thymocyte apoptosis. In this study, we demonstrated that SEB induced a substantial reduction in thymocyte numbers in BALB/c, B10. D2 (H-2(d) haplotype), B10.BR, C3H/HeJ, C3H/HeN (H-2(k)), and (BALB/c x B6)F1 (H-2(dxb)), but caused little or no effect in I-E- strains such as B6, B10, A.BY (H-2(b)), and A.SW (H-2(s)) mice. Elimination of CD4(+)CD8(+) cells predominantly accounted for the thymocyte loss, although the numbers of other subpopulations may also be reduced. Thymocyte apoptosis was shown by an increase in the level of DNA fragmentation in BALB/c but not in B6 mice after SEB administration. Treatment with anti-I-Ed monoclonal antibody to BALB/c mice blocked SEB-induced thymocyte apoptosis when anti-I-Ad exerted less effect. In contrast to SEB, staphylococcal enterotoxin A led to comparable levels of thymus atrophy in BALB/c and B6 mice. Studies on the surface marker expression indicated that CD25 expression was upregulated on BALB/c mouse thymocytes but with only a moderate increase in B6 mice. The CD4(+)CD8(+) cells were the major (>90%) population that expressed elevated levels of CD25 in BALB/c mice. An increase in the expression of TCRalphabeta, CD3, and CD69 surface markers was also observed on thymocytes from BALB/c mice, but not from I-E- strains. The differential response of I-E+ and I-E- mice to SEB may be exploited as a model for the study of apoptosis in the thymus.
Nasopharyngeal carcinoma (NPC) is an epithelial cancer that is causally associated with Epstein-Barr virus (EBV) infection. NPC tumor biopsies are characterized histopathologically by an abundant infiltration of nonmalignant lymphocytes. We analyzed the expression of various cytokines in NPC tissues to investigate the interaction of the infiltrating lymphocytes and tumor cells. Analysis using reverse transcriptase-PCR revealed the expression of a panel of cytokines in the NPC biopsies: interleukin (IL)-1alpha, IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-10, IFN-gamma, tumor necrosis factor-alpha, transforming growth factor-beta, and IL-1 receptor types I and II. Elevated expression of IL-1alpha and IL-1beta was observed in primary tumors and NPC metastases compared to control tissues. Interestingly, this increased expression correlated with the EBV-encoded viral IL-10 transcript. To determine which cells were responsible for producing IL-1, we determined the cellular constituents of NPC biopsies by immunoflow cytometric analysis. On the basis of data from these analyses, the three major specific cell populations, epithelial cells, CD4+ T cells, and CD8+ T cells, were selected from five NPC tumors using specific, antibody-coated paramagnetic beads. Reverse transcriptase-PCR of RNA from these fractionated cells showed that transcripts of IL-1alpha and IL-1beta were present not only in the malignant epithelial cells but also in CD4+ T cells infiltrating the tumor, a finding confirmed by immunohistochemical staining. We hypothesize that the unusual synthesis of IL-1alpha and IL-1beta by EBV-positive epithelial cells as well as by CD4+ T cells might contribute to lymphocyte infiltration and/or tumor growth during NPC development.
BACKGROUND/AIMS: Somatostatin and its analogue have been shown to provide beneficial effects in the management of portal hypertension and hyperdynamic circulation. The current study was undertaken to evaluate the effects of lanreotide, a sustained-release somatostatin analogue, on hemodynamics in rats with portal hypertension. METHODS: Immediately after portal vein stenosis, rats were randomly assigned to receive vehicle or a single intramuscular injection of lanreotide 10 mg/kg. Hemodynamic measurements (radioactive microsphere technique) with portal systemic shunts determinations were performed on the 4th and 8th day after surgery, respectively. RESULTS: On the 4th day after surgery, rats treated with lanreotide had significantly lower cardiac index and higher systemic vascular resistance than rats treated with vehicle, while these values were no different on the 8th day after portal vein stenosis. In contrast, the elevation of portal pressure, portal tributary blood flow, and splanchnic fraction of cardiac output had ameliorated following lanreotide administration associated with an increase in splanchnic arterial resistance. Portal systemic shunts were lower in rats receiving lanreotide than in rats receiving vehicle. CONCLUSION: The current study showed that a single injection of sustained-release lanreotide in rats with portal vein stenosis delayed the development of peripheral arterial vasodilatation and hyperdynamic circulation, while it modified the evolution of portal hypertension and splanchnic hyperemia. This treatment also prevents, in part, the development of portal systemic shunts in rats with portal vein stenosis.
BACKGROUND: Herpes simplex virus (HSV) is a common pathogen with two serotypes: HSV-1 and HSV-2. HSV infection does not pose much of a threat to an immunocompetent host but to an immunocompromised host or a neonate the infection can be fatal. The Enzyme-Linked Virus Inducible System (ELVIS) employs a genetically altered baby hamster kidney (BHK) cell line that allows for the rapid overnight detection of HSV but also includes an immunofluorescent stain for the simultaneous detection and typing of HSV-1 and HSV-2. OBJECTIVE: To evaluate the ELVIS HSV ID/Typing System in comparison with HSV identification and typing in primary rabbit kidney (PRK) cells grown in shell vials. STUDY DESIGN: Over a period of 6 weeks, 130 specimens were submitted to the diagnostic virology laboratory and cultured for the presence of HSV. Two PRK shell vials and one ELVIS BHK shell vial were inoculated with patient specimen. PRK shell vials were observed for cytopathic effect (CPE) for up to 4 days. When CPE was observed the PRK shell vials were fixed and one shell vial was stained with HSV-1 monoclonal antibody (Mab) and the other was stained with HSV-2 Mab. The coverslips were observed under the fluorescent microscope for specific apple-green fluorescence. The BHK shell vials were incubated overnight, fixed, and stained with galactopyranoside (X-Gal). If blue cells were present, the specimen was positive for HSV. The coverslip was then observed under the fluorescent microscope for the presence of specific apple-green fluorescence, indicating HSV-2. If no specific apple-green stain was observed, the coverslip was stained with a fluorescent conjugated goat anti-mouse IgG to determine the presence of HSV-1. RESULTS: Of the 130 specimens, PRK shell vials detected 43 positive HSV; 30 were HSV-2 and 13 were HSV-1. The ELVIS BHK shell vials detected 42 positive HSV; 30 were HSV-2 and 12 were HSV-1. One low titer specimen was not identified as being HSV positive. Two specimens were not directly typed by the ELVIS system. One specimen had only one blue cell present and did not show specific staining for either HSV-1 or HSV-2. The other specimen had only five blue cells present and only one fluorescent cell present that was difficult to type. As suggested by the manufacturer's instructions, both specimens that were not directly typed were re-grown overnight from their supernatants and were correctly identified and typed. CONCLUSION: The ELVIS HSV ID/Typing System is a rapid, highly specific and sensitive method of overnight HSV detection and typing.
1. Flavonoids display a wide range of pharmacological properties including anti-inflammatory. Anti-mutagenic, anti-carcinogenic and anti-cancer effects. Here, we evaluated the effects of eight flavonoids on the tumour cell proliferation, cellular protein phosphorylation, and matrix metalloproteinase (MMPs) secretion. 2. Of the flavonoids examined, luteolin (Lu) and quercetin (Qu) were the two most potent agents, and significantly inhibited A431 cell proliferation with IC50 values of 19 and 21 micronM, respectively. 3. The epidermal growth factor (EGF) (10 nM) promoted growth of A431 cells (+25+/-4.6%) and mediated epidermal growth factor receptor (EGFR) tyrosine kinase activity and autophosphorylation of EGFR were inhibited by Lu and Qu. At concentration of 20 micronM, both Lu and Qu markedly decreased the levels of phosphorylation of A431 cellular proteins, including EGFR. 4. A431 cells treated with Lu or Qu exhibited protuberant cytoplasmic blebs and progressive shrinkage morphology. Lu and Qu also time-dependently induced the appearance of a ladder pattern of DNA fragmentation, and this effect was abolished by EGF treatment. 5. The addition of EGF only marginally diminished the inhibitory effect of luteolin and quercetin on the growth rate of A431 cells, treatment of cellular proteins with EGF and luteolin or quercetin greatly reduced protein phosphorylation, indicating Lu and Qu may act effectively to inhibit a wide range of protein kinases, including EGFR tyrosine kinase. 6. EGF increased the levels of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9), while Lu and Qu appeared to suppress the secretion of these two MMPs in A431 cells. 7. Examination of the relationship between the chemical structure and inhibitory effects of eight flavonoids reveal that the double bond between C2 and C3 in ring C and the OH groups on C3' and C4' in ring B are critical for the biological activities. 8. This study demonstrates that the inhibitory effects of Lu and Qu, and the stimulatory effects of EGF, on tumour cell proliferation, cellular protein phosphorylation, and MMP secretion may be mediated at least partly through EGFR. This study supports the idea that Lu and Qu may have potential as anti-cancer and anti-metastasis agents.
The hemodynamic effects of tetramethylpyrazine (TMP) and tetrandrine (TET), both alkaloids isolated from Chinese herbs Ligusticum wallichii Franch and Stephania tetrandra S. Moore, respectively, were assessed in anesthetized cirrhotic rats. TMP induced dose-dependent decreases of portal venous pressure (P.V.P.) and mean arterial pressure (M.A.P.) after intravenous infusion. The maximum percentage reduction of P.V.P. after TMP was 3.6 +/- 0.8%, 6.8 +/- 0.5%, and 17.8 +/- 0.6% of baseline, respectively, for the dosages given (3.0, 9.9 and 30.0 mg/kg). Similarly, TET induced dose-dependent decreases of P.V.P. and M.A.P. The maximum percentage reduction of P.V.P. after TET was 5.4 +/- 1.0%, 9.2 +/- 0.8%, and 23.7 +/- 1.2% of baseline, respectively, for the dosages given (2.0, 6.6 and 20.0 mg/kg). Total peripheral resistance was also reduced by TMP as well as TET. Our results showed that TMP and TET induced P.V.P. reduction in cirrhotic rats, together with reduction in M.A.P. and total peripheral resistance.
Prostaglandins biosynthesis and nitric oxide production have been implicated in the process of carcinogenesis and inflammation. In this study, we investigated the effect of various flavonoids and (-)-epigallocatechin-3-gallate on the activities of inducible cyclooxygenase (COX-2) and inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. Apigenin, genistein and kaempferol were markedly active inhibitors of transcriptional activation of COX-2, with IC(50) < 15 microM. In addition, apigenin and kaempferol were also markedly active inhibitors of transcriptional activation of iNOS, with IC(50) < 15 microM. Of those compounds tested, apigenin was the most potent inhibitor of transcriptional activation of both COX-2 and iNOS. Western and northern blot analyses demonstrated that apigenin significantly blocked protein and mRNA expression of COX-2 and iNOS in LPS-activated macrophages. Transient transfection experiments showed that LPS caused an approximately 4-fold increase in both COX-2 and iNOS promoter activities, these increments were suppressed by apigenin. Moreover, electrophoretic mobility shift assay (EMSA) experiments indicated that apigenin blocked the LPS-induced activation of nuclear factor-kB (NF-kB). The inhibition of NF-kB activation occurs through the prevention of inhibitor kB (IkB) degradation. Transient transfection experiments also showed that apigenin inhibited NF-kB-dependent transcriptional activity. Finally, we showed that apigenin could inhibit the IkB kinase activity induced by LPS or interferon-gamma. The results of further studies suggest that suppression of transcriptional activation of COX-2 and iNOS by apigenin might mainly be mediated through inhibition of IkB kinase activity. This study suggests that modulation of COX-2 and iNOS by apigenin and related flavonoids may be important in the prevention of carcinogenesis and inflammation.
OBJECTIVE: The purpose of this study was to investigate the therapeutic effects of tetramethylpyrazine, an alkaloid isolated from a Chinese herb Ligusticum wallichii Franch, on portal hypertensive rats. METHODS: There were three groups of animals: partial portal vein ligated (PVL) rats, bile duct ligated (BDL) rats and sham-operated (Sham) rats. Each rat in every group was given only one of three treatment regimens: tetramethylpyrazine 30 or 50 mg/kg/12 h, or vehicle (0.2 N HCl, 0.7 ml/12 h). There were seven rats allocated to each regimen, with a total of 63 rats studied. Tetramethylpyrazine or vehicle was given via gastric gavage every 12 h for 8 days, starting just after PVL or 3 weeks after BDL, and haemodynamic parameters were measured thereafter. RESULTS: Both PVL and BDL rats exhibited portal hypertensive and hyperdynamic state as compared with Sham rats. Eight-day tetramethylpyrazine treatment induced dose-dependent reductions of portal venous pressure (PVP), mean arterial pressure (MAP), and total peripheral resistance (TPR) in both PVL and BDL rats. Tetramethylpyrazine at 30 and 50 mg/kg/12 h induced PVP reduction by 10.2 and 16.1% in PVL rats, and 10.5 and 14.8% in BDL rats, respectively, as compared with the vehicle group. There were no significant changes of cardiac index or heart rate (HR) after tetramethylpyrazine treatment in either PVL or BDL rats. In the Sham rats, tetramethylpyrazine did not significantly change PVP, MAP, HR or TPR, despite a tendency of reduction. CONCLUSION: Our results showed that 8-day treatment of tetramethylpyrazine induced reductions of both portal venous and systemic arterial pressure in portal hypertensive rats with and without cirrhosis. Overall, the therapeutic effects are neither outstandingly efficacious nor altogether beneficial.
Latent membrane protein 1 (LMP-1) is the only Epstein-Barr virus (EBV)-encoded oncogenic protein that has been detected in nasopharyngeal carcinoma (NPC), a cancer that is closely associated with EBV. Previous in-vitro studies have demonstrated that LMP-1 can upregulate epidermal growth factor receptor (EGFR) in epithelial cells. It was not established whether this cellular effect exists in NPC. To assess the association between LMP-1 and EGFR in NPC tissues, 60 NPC specimens were examined by immunohistochemistry using anti-LMP-1 antibody (CS 1-4) and anti-EGFR antibodies (EGFR 1, EGFR 1005). The results revealed that 41 (68.3%) specimens were immunopositive for LMP-1 and 44 (73.3%) specimens over-expressed EGFR. Morphologically, the expressions of LMP-1 and EGFR were homogeneously distributed in the tumor nests. In addition, the correlation between LMP-1 and EGFR was statistically significant (P<0.001, chi2 test, d.f. = 1). To elucidate further the correlation between LMP-1 and EGFR in vivo and in situ, an indirect dual immunofluorescence assay was conducted, using secondary antibodies conjugated with fluorescein isothiocyanate (FITC) or indocarbocyanine (Cy3). The results disclosed an intimate co-expression of LMP-1 and EGFR. In summary, the data indicate that over-expression of EGFR is a common phenomenon in NPC, and that EGFR is co-expressed with LMP-1 in NPC. Thus, EBV may play a role in the tumorigenesis of NPC through the effects of LMP-1 and EGFR.
AIMS/BACKGROUND: The purpose of this study was to investigate the therapeutic effects of terlipressin, alone or in combination with DL-028, a synthetic alpha 1-adrenoceptor antagonist on anesthetized portal hypertensive rats. METHODS: Portal hypertension was induced by either partial portal vein ligation (PVL) or bile duct ligation (BDL) in Sprague-Dawley rats. Each portal hypertensive rat received only one of the two regimens: vehicle plus terlipressin or DL-028 plus terlipressin. Terlipressin dosage was 0.017 mg/kg/min infused for 3 min, while vehicle or DL-028 (0.50 microgram/kg/min) was continuously infused for 40 min, starting 10 min before terlipressin infusion. RESULTS: In PVL rats, infusions of vehicle plus terlipressin induced significant, maximum reduction of portal venous pressure (PVP, -11.0 +/- 1.8%) and prominent elevation of mean arterial pressure (MAP, 50.3 +/- 9.0%) from baseline. Infusions of DL-028 plus terlipressin induced maximum PVP reduction (-17.5 +/- 2.8%) and MAP elevation (39.8 +/- 7.4%). In BDL rats, infusion of vehicle plus terlipressin also induced significant, maximum reduction of PVP (-6.8 +/- 2.1%) and prominent elevation of MAP (61.4 +/- 7.8%) from baseline. Infusions of DL-028 plus terlipressin induced maximum PVP reduction (-17.9 +/- 2.2%) and MAP elevation (47.9 +/- 7.4%). Compared to vehicle plus terlipressin, DL-028 significantly enhanced portal hypotensive effects of and attenuated systemic pressor effects of terlipressin in both PVL and BDL rats. CONCLUSIONS: Our results suggest that terlipressin, alone or in combination with DL-028, induced portal hypotensive effects in portal hypertensive rats. The combination of terlipressin with DL-028 was beneficial in enhancing the portal hypotensive effects and ameliorating the systemic pressor effects of terlipressin.
OBJECTIVE: Octreotide has potentially beneficial effects in patients with cirrhosis. However, the effects of octreotide on central hemodynamics and oxygen use have not been established. The present study was undertaken to evaluate the effect of octreotide on central hemodynamics and oxygen use in patients with viral cirrhosis. METHODS: Twenty-five patients with cirrhosis were enrolled in the study. They were randomly assigned to receive either placebo (n = 10) or a continuous infusion of 100 microg/h of octreotide after an initial 100-microg bolus (n = 15). Hemodynamic measurements and oxygenation values were obtained before and 60 min after octreotide or placebo administration. RESULTS: Placebo administration did not have any effect on hemodynamic and oxygenation values. In patients who received octreotide, systemic hemodynamic values including cardiac index, mean arterial pressure, and systemic vascular resistance were not affected. The mean pulmonary arterial pressure tended to increase after octreotide administration but was statistically insignificant. There was a significant increase in pulmonary arterial vascular resistance, whereas the pulmonary capillary wedge pressure and right atrial pressure were significantly decreased. Arterial oxygen tension, systemic oxygen uptake, and oxygen extraction ratio were significantly decreased after octreotide administration, whereas oxygen transport as well as arterial and mixed venous oxygen contents remained unchanged. CONCLUSIONS: In patients with viral cirrhosis, octreotide administration exerted a significant effect on pulmonary circulation. It also resulted in a decrease in systemic oxygen uptake and oxygen extraction ratio. These results suggested that octreotide may impair tissue oxygenation in patients with viral cirrhosis.
Two nasopharyngeal carcinoma (NPC) cell lines and one keratinocyte cell line could be infected with Epstein-Barr virus (EBV) by cocultivation with virus-producing cells but not by cell-free virus. Using porous culture inserts to manipulate the cell-to-cell contact, we demonstrated that contact between EBV donor B cells and EBV recipient epithelial cells was required for the infection. Cell-to-cell contact not only provided a CR2-independent route of infection but also enhanced CR2-mediated infection in a synergistic manner. Activity of two EBV promoters (Cp and Wp) and expression of EBNA2 were detected in the infected population. A small proportion of the infected cells spontaneously entered an EBV lytic state, which could be induced prominently by chemical treatment. This study provides information on how EBV may infect epithelial cells in vivo, such as at the onset of NPC development.
OBJECTIVE: For years, blood transfusion centers in Taiwan have used the Quantitative Buffy Coat (QBC(R)) Hematology System for platelet counts on capillary blood samples in the laboratory screening of apheresis donors. The system has not been evaluated for the prediction of yields in plateletpheresis. Methods : The QBC instrument was evaluated for reproducibility of platelet counts and compared with five electronic cell counters. We also collected both capillary and venous blood from voluntary donors before donation and counted platelets, comparing the QBC system and an electronic blood cell counter (Sysmex K1000). The correlation between donors' predonation platelet counts and plateletpheresis yields was analyzed. RESULTS: The R values for platelet counts between the QBC Hematology System and other electronic counters are lower (0.759-0. 890) than among the electronic counters (0.929-0.973). The mean capillary platelet count and the mean venous platelet count were 241. 9+/-50.3x10(3)/microl and 233.2 +/-47.9x10(3)/microl by the QBC system, and 244.9+/-54.1x10(3)/microl and 218.9+/-46.5x10(3)/microl by the Sysmex K1000, respectively. Linear regression analysis showed that platelet yields correlated well with donors' predonation platelet counts using the Sysmex K1000 counter (R = 0.777- 0.890, p<0.001), but not with the QBC system (R = 0.326 approximately 0.755, p<0.05). CONCLUSION: The QBC Hematology System is not accurate enough to determine predonation platelet counts that are to be used for calculating the number of processing cycles for plateletpheresis.
We operated on 111 patients with 159 congenital club feet with the aim of correcting the deformity and achieving dynamic muscle balance. Clinical and biomechanical assessment was undertaken at least six years after operation when the patient was more than 13 years of age. The mean follow-up was for 11 years 10 months (6 to 36 years). Good and excellent results were obtained in 91.8%. Patients with normal function of the calf had a better outcome than those with weak calf muscles. The radiological changes were assessed in relation to the clinical outcome. The distribution of pressure under the foot was measured for biomechanical assessment. Our results support the view that muscle imbalance is an aetiological factor in club foot. Early surgery seems to be preferable. It is suggested that operation should be undertaken as soon as possible after the age of six months, although it may be carried out up to the age of five years. The establishment of dynamic muscle balance appears to be an effective method of maintaining correction. Satisfactory long-term results can be achieved with adequate appearance and function.