Volume 111 · Issue 06 · 1998

Chronic hepatitis B (HBV) infection is a serious global health problem affecting around 300 million individuals. Of these, many will die of cirrhosis or hepatocellular carcinoma. To date, interferon has been widely used to treat chronic hepatitis B infection. Unfortunately, the use of interferon is not satisfactory in Chinese, because most infections are vertical, leading to long-lasting immune tolerant state.

OBJECTIVE To establish the replicated-deficient recombinant adenovirus-mediated thymidine kinase/acyclovir (Adtk/ACV) system and to evaluate its suicide effect on rat C6 brain gliomas in vitro and in vivo. METHODS The plasmid pAdtk and pJM17 were co-infected into 293 cells (adenovector packaging cells) and the RESULTS were identified by polymerase chain reaction (PCR) assay. After the glioma C6 cells were transduced by Adtk at different multiplicity of infection (MOI) and exposed to different concentrations of ACV or gancyclovir (GCV), the cell survival curves were studied, and the cell surface was observed with scanning electronic microscopy (SEM). C6 gliomas in vivo at different inoculation days were injected with Adtk intratumorally and ACV intraperitoneally daily, and the survival duration and histologic changes of the rats were observed. RESULTS The infectious Adtk virions had a suicide effect which was enhanced with the increase in MOIs of Adtk and ACV doses along with bystander effect. Under scanning electronic microscope, special pathologic changes were observed. ACV had a similar effect as GCV but a higher dose was used. The survival duration in day 3, day 6 and day 8 groups exceeded 90 days, and the rats in day 10 group survived 28.5±4.6 days, but the survival duration in untreated C6 group and AdLacZ/ACV (adenovirus-mediated LacZ/ACV) treated group were 16.8±3.1 and 14.0±2.2 days respectively. CONCLUSIONS Adtk/ACV system can effectively kill the rat brain gliomas in vitro and in vivo.

OBJECTIVE To further investigate the impact of impaired microvasculature of spinal cord and its physiological compensation on postoperative morbidity after intramedullary microsurgery. METHODS In 120 cats, the segmental anterior longitudinal spinal arteries (ALSA), the posterior longitudinal spinal arteries (PLSA), and the unilateral radiculomedullary arteries (RMA) were selectively coagulated in different patterns. Hydrogen electrode technique was used to detect the changes of regional blood flow of the spinal cord at different segments. Benzidine dihydrochloride (BDHC) staining was used to observe the microvascular pattern of the spinal cord, tetrazolium chloride (TTC) staining was applied to morphometric analysis of the ischemic area, and hematoxylin-eosin staining was applied to histologic examination. RESULTS When the segmental ALSA was injured, the blood flow of the gray matter and white matter decreased greatly. Since the central arteries were the terminal blood supply arteries, no compensation occurred after the injury. The blood flow of the segment below the impaired segment hardly changed, indicating that the direction of the blood flow in ALSA altered to adapt the changes of the microvasculature. Injury to the unilateral PLSA and RMA at both cervical and lumbar area only caused a minor decrease in the regional blood flow, unless the perimedullary arterial system was considerably injured. In the thoracic medullary segment, the sparse microvasculature was the main cause for the segment vulnerable to ischemia and infarction. This was caused by not only the rarity of RMA as an anatomic factor, but also the small number and low activity of the neurons at this area. After microsurgery, the impairment and decompensation of the microvasculature were closely related to the ischemic volume of and pathological changes in the spinal cord. CONCLUSIONS The impairment and decompensation of microvasculature after microsurgery are the rudimentary causes of spinal cord ischemia. During operation, one should protect the terminal arteries to decrease the severity of injury to the perimedullary system, and do the best to avoid disturbance of microvasculature to accelerate the recovery of postoperative ischemia and neurological dysfunction of the spinal cord.

OBJECTIVE To explore the mechanism of β-amyloid peptide (β-AP) in Alzheimer's disease at ionic channel level. METHODS Hippocampal CA1 neurons of 7-21 days' rats were acutely dissociated and the effects of β-AP on transient outward potassium current were observed by a whole-cell recording patch clamp technique. RESULTS β-AP can significantly block transient potassium current in dose-dependent, time-dependent and partly voltage-dependent manners. CONCLUSIONS β-AP may decrease the membrane conductance of K+ channels in hippocampal neurons, playing an important role in the pathophysiological mechanism of Alzheimer's disease.

OBJECTIVE To investigate preliminarily the value of phrenic nerve conduction (PNC) and diaphragmatic motor evoked potentials (MEPs) in the evaluation of various respiratory dysfunction (RDF). METHODS Thirty-four patients with various RDF, (19 patients with neurogenical diseases and 15 patients with respiratory disorders) were investigated. Fifty healthy volunteers served as controls. The phrenic nerve was cutaneously stimulated by electrical pulse current at the midpoint of the posterior border of the sternomastoid muscle, and the diaphragmatic muscle compound action potentials (DCAP) were recorded between the 7th and 8th intercostal space and xiphoid process. When the magnetic transcranial stimulation (MTS) of the cortex was given, the recordings were made under the condition of maximal deep inspiration. RESULTS All patients with myopathies had normal PNC. The patients with Guillain Barre syndrome (GBS), hereditary motor and sensory neuropathy (HMSN) and myasthenic crisis had abnormal PNC. The findings in PNC studies remarkably correlated with RDF, while serial examinations were performed in the patients with GBS and myasthenia gravis (MG). In 7 patients with sleep apnea syndrome (SAS), 4 had abnormal PNC, and 2 of 3 patients with chronic obstructive pulmonary diseases (COPD), and 1 of 5 patients with chest tightness or breathlessness on the supine position showed decreased amplitude. When MEPs were recorded, 3 of 5 patients showed abnormal SAS (1 had no response, 2 lower amplitude). Three patients with COPD had normal MEP. CONCLUSIONS PNC studies could not only evaluate neuromuscular RDF and predict the outcome of diseases, but also supply additional information about diaphragmatic dysfunction for the RDF caused by respiratory disorders. The results of PNC and diaphragmatic MEP may differentiate the types of SAS.

OBJECTIVE To detect the gene defect of mitochondrial DNA (mtDNA) from skeletal muscles in 2 patients with chronic progressive external ophthalmoplegia (CPEO). METHODS After extraction of mtDNA, Southern hybridization was performed after restrictive digestion by Pvu Ⅱ, EcoRI, Hind Ⅲ, and Sacl. Then, we carried out polymerase chain reaction (PCR) and the enzyme digestion of the PCR products. Finally, mtDNA sequencing was done by automatic DNA sequence analyzer. RESULTS In case 1, a 5 kb deletion was found by Southern blot analysis and PCR. And dosage analysis showed a heteroplasmic change with 44% mtDNAs deleted. In case 2, PCR plus restriction endonuclease Pvu Ⅱ digestion demonstrated a mutation which was confirmed by DNA sequencing to be a single base substitution (T→C) inducing a novel Pvu Ⅱ site around 10,909 on mtDNA sequence. The laser image analyzer measurement revealed the mutation was almost homologous (99.4% mutant). CONCLUSIONS In case 1, a 5 kb deletion found in mtDNA is called "common deletion" according to the literature. In case 2, a novel Pvu Ⅱ site was found. It seems to be a de novo point mutation affecting ND4 in published CPEO research and is first reported in Chinese population. This point mutation does not induce an amino acid(Phe) change according to the published human mitochondrial genetic code as well as the mtDNA sequence. Whether it affects the translation efficiency or transportation of signals between mitochondrial and nuclear genome needs further studies.

OBJECTIVE To investigate the role of catecholamines in the pathogenesis of portal hypertension. METHODS Serum epinephrine (E) and norepinephrine (NE) concentrations in the peripheral vein, portal vein and superior vena cava (SVC) were measured by high pressure liquid chromatography in 38 portal hypertensive patients, 28 idiopathic hypertensive patients and 34 controls, respectively. RESULTS Peripheral venous E concentrations in portal hypertensive patients and controls were 57.5±37.4 ng/L and 23.5±11.2 ng/L, respectively (P<0.01), and peripheral venous NE concentrations were 451.1±381.2 ng/L and 183.0±83.3 ng/L, respectively (P<0.01). Compared with controls, peripheral venous E (54.9±39.9 ng/L vs 23.5±11.2 ng/L, P<0.01) and NE (524.3±219.9 ng/L vs 183.0±83.3 ng/L, P<0.01) in idiopathic hypertensive patients were also significantly increased. E and NE in SVC, portal vein and peripheral artery in portal hypertensive patients were also increased, but only the elevation of E in SVC was statistically significant (207.2±55.4 ng/L vs 83.7±46.7 ng/L, P<0.05). CONCLUSIONS Our results reveal significant metabolic disorders of E and NE in portal hypertensive patients, which may play an important role in the pathogenesis of portal hypertension.

OBJECTIVE To investigate the changes of alpha-1 adrenergic receptors in cirrhotic liver and the relationship between the changes and the pathogenesis of portal hypertension. METHODS The concentration and affinity of alpha-1 adrenergic receptors in the liver plasma membranes of posthepatitic cirrhotic patients with portal hypertension were quantitatively measured using radioligand binding analysis. RESULTS Compared with 8 controls without hepatic pathological changes, the maximal binding capacity (Bmax) of 9 posthepatitic cirrhotic patients decreased (129.1±12.0 vs 142.1±14.1 fmol/mg protein, P>0.05), dissociation constant (Kd) values increased (0.3945±0.0974 vs 0.2382±0.0548 nmol/L, P<0.01), and the receptor maximal content (RMC) decreased (417.4±76.8 vs 739.9±167.6 fmol/g liver, P<0.01). CONCLUSIONS The decreased concentration and affinity of alpha-1 adrenergic receptors may play an important role in the metabolic disturbances of catecholamines often seen in some cirrhotic patients, and have implications in the pathogenesis of portal hypertension.

OBJECTIVE To confirm the existence of plaque or stenosis in the extracranial carotid arteries of patients with transient ischemia attack (TIA) or stroke, and to analyze the prevalence of extracranial carotid atherosclerotic stenosis, as well as the relation between the hemispheric symptoms and the degree of stenosis. METHODS From January 1995 to March 1996, 188 patients underwent routine carotid artery duplex scan at Zhongshan Hospital, Shanghai. Of the 188 patients, 134 had TIA or stroke in the carotid territory during the previous 12 months, 54 were with peripheral arterial occlusive disease (PAOD). All patients were divided into three groups, that is, stroke/TIA group (Group 1, n = 128), PAOD group (Group 2, n = 36), and stroke/TIA + PAOD group (Group 3, n = 24). The classification of degree of stenosis in our study was as same as that applied by North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST). RESULTS A total of 376 internal carotid arteries were examined by duplex scanning in this study. The prevalence of severe stenosis in the three groups was 12.5%, 8.3% and 37.5% separately. The severity of stenosis had a close relation with patients' symptoms (P<0.01). CONCLUSIONS Patients with stroke or TIA have atherosclerotic plaques in the carotid arteries. The prevalence of extracranial carotid stenosis is comparable to that reported in the literature. PAOD may be helpful to identify patients at high risk for severe carotid stenosis. Carotid duplex scanning should be performed as a routine examination for patients with stroke, TIA, and PAOD.

OBJECTIVE To test the hypothesis that in a rat model of acute intestinal ischemia/reperfusion injury, endotoxemia from the gastrointestinal tract would play a role in mediating tumor necrosis factor (TNF) response and remote organ dysfunction. METHODS Wistar rats underwent 45 minutes of superior mesenteric artery occlusion followed by 6 hours of reperfusion. The rats were treated intravenously with either TNF monoclonal antibody (MoAb) or saline solution 90 minutes prior to the onset of ischemia. RESULTS Significant elevation of plasma TNF level in both portal and systemic circulation was detected immediately after the onset of reperfusion. The level peaked at two hours after reperfusion (P<0.01). Similarly, a remarkable TNF mRNA expression in the intestine in controls was detected at 0.5 hour post-reperfusion, and sustained a marked elevation throughout the observation period (P<0.05-0.01). TNF elevation was found associated with gut-origin endotoxemia, and the maximal TNF response occurred approximately 0.5-2 hours after the initial appearance of endotoxin in the portal vein. Concomitantly, multiple organ dysfunction in response to local ischemic insult was also observed in untreated controls upon reperfusion, but it was significantly attenuated by pretreatment with MoAb against TNF. CONCLUSIONS Intestinal injury can result in the gut becoming a cytokine-liberating organ. The escape of endotoxin and bacteria from the gut may be responsible for the TNF expression and release, which would be an important mechanism underlying pathophysiological alterations associated with intestinal ischemia/reperfusion injury.

OBJECTIVE To study the replicative competency and pathogenicity of precore gene mutants of duck hepatitis B virus (DHBV) in the duck model. METHODS Three site-directed point mutations in the precore region of cloned DHBV were constructed. Head-to-tail dimers were formed. The three plasmids were named: pEDM1-2 (initiation codon ATG mutated to TTG), pEDM2-2 (an "A" was inserted down stream of codon 12, leading to frame shift in the distal end of precore region), pEDM3-2 (codon 38 was changed from TAT to TAA, leading to a stop codon at the 3'-end). Mutants and wild-type cloned DNA dimers were first separately used to transfect LMH cells (a chicken hepatoma cell line) and viruses were collected from supernatant and used to infect 6 one-day-old ducklings per group. Serum duck hepatitis B surface antigen (DHBsAg) and DHBV DNA were assayed. Six weeks after infection, ducks were killed and liver tissues were studied for histopathological changes. RESULTS After transfection, pEDM1-2, pEDM2-2 and pEDM3-2 expressed similar level of DHBsAg. Replication of pEDM1-2 and pEDM3-2 was similar to that of the wild type clone, while pEDM2-2 replicated at a significantly decreased level. Infection study employing the supernatant of transfected cells was as follows: pEDM1-2 infected 5/6 ducklings, pEDM2-2 non infected, pEDM3-2 infected 2/6 ducklings, wild type virus infected 6/6 ducklings. Positive serum samples from both pEDM1-2 and pEDM3-2 were at a lower serum DHBV level compared to that of the wild type virus. Pathological changes were more significant in pEDM3-2 infected duck livers, with numerous inflammatory cells in portal tract and infiltration into parenchyma. CONCLUSIONS Mutations in the initiating codon or generation of a stop codon at the 3'-end of the precore region resulted in decreased replication competency of DHBV, while frame-shift mutation of the precore region, covering the epsilon encapsidation signal abolished the replication of DHBV. When the mutants replicated in hosts, more severe pathological changes were observed in ducks infected with mutant harboring a stop codon at the 3'-end. Data suggest that replicative-competent DHBV precore mutant can be more pathogenic than wild-type DHBV.

In this paper it is intended to unify the standard lead and the augmented unipolar limb lead (aV lead) system into a single lead system. Viewing from the angle of lead axes, the standard leads and the aV leads are not only reflecting the frontal plane vector, but are also actually complementary to each other. By now it has become quite obvious that they not only can, but also should be unified into a single system. Viewing these six leads (from standard lead and aV lead systems), starting from aVL, lead Ⅰ, reversed aVR, lead Ⅱ, aVF to lead Ⅲ, an arc including approximately 150 degrees is formed. It is suggested that this unified system may be called "F" system with each of the above leads renamed as F1-F6 leads, respectively, since they are all reflecting the vectors of the frontal plane. In this F-lead system each lead is approximately 30 degrees apart. If such a system would be adopted it is only necessary to time the amplitude of the P, QRS and T of aV lead by 1.15 (a figure calculated by vector analysis). If this suggestion is widely adopted there will be only a F lead system for the frontal vectors and the present V system for the "horizontal" vectors in the electrocardiogram.

Escherichia coli has seldom been reported to cause pseudobacteremia. The investigation of an outbreak of amoxycillin-clavulanic acid-resistant E. coli pseudobacteremia is described. Seventeen cases occurred over a five-day period. The source of the E. coli was traced to the blood culture specimen of a patient (index patient) with genuine bacteremia as a result of urinary tract infection. The other 16 case-patients had pseudobacteremia which was found to be the result of cross-contamination during subculture of blood specimens. The E. coli strain was carried over from the culture bottle of the index patient, through the contaminated gloved hands of a technician to the culture bottles of the other 16 cases. Although the pseudobacteremia occurred over a five-day period, they all resulted from cross-contamination during blood culture processing within one day. An early outbreak investigation was prompted by the unusual finding of amoxycillin-clavulanic acid resistance in the case E. coli isolates in a short period. The relatedness of the E. coli strains from the 17 cases was confirmed by arbitrary-primed polymerase chain reaction. Clinicians should be alerted to the possibility of a blood E. coli isolate being a contaminant despite its predominant role as a true pathogen.