Biomedical subjects

H Li

Publications and source records attributed to H Li.

At least 1,459 records · Page 81Linked to original sources

PubMed1996

Expression of extracellular matrix macromolecules around demineralized freeze-dried bone allografts.

In the present study histochemical techniques were used to identify specific macromolecular components of the extracellular matrix associated with the tissue reaction to demineralized freeze-dried bone allografts (DFDBA) placed under barrier membranes for ridge augmentation. Small biopsies were obtained from tissues underneath the membranes at various times after placement of the DFDBA and processed for routine immunohistochemistry. Sections were stained with antibodies to osteocalcin, collagen type I, collagen type III, decorin, and biglycan. Non-immune serum, irrelevant antibodies, and omission of the primary antibodies served as negative controls. Histologic examination of the biopsies revealed allograft particles surrounded by well-formed fibrous connective tissue with little or no evidence of new bone formation. Vital autogenous bone fragments were present in the peripheral portions of the biopsies and served as positive controls for comparative purposes with the DFDBA particles. Only 7 out of the 20 biopsies studied were found to have any signs of bone formation around the DFDBA particles and in these such bone formation was irregular and inconsistent around the DFDBA particles. Around the periphery of the allograft particles, osteocalcin, collagen type I, collagen type III, decorin, and biglycan all showed relatively strong staining. Osteocalcin staining was also noted within the vital bone matrix but not in the surrounding fibrous connective tissue. Decorin, biglycan, collagen type I, and collagen type III were also found within the vital bone matrix. None of these antibodies stained the DFDBA particles. The unremarkable osteogenic response of the tissues to the DFDBA particles after healing periods of up to 12 months raises questions as to the predictability of these agents in inducing new bone.

Adult↗

PubMed1996

Changes in clinical features of fungemia in a Japanese University Hospital over a 12-year period.

Forty-five patients with fungemia during 1982-1993 (periods I = 1982, II = 1986-1989, III = 1990-1993) in a Japanese university hospital were reviewed to follow changes in the clinical features of fungemia. The percentage of fungi among microorganisms isolated from blood cultures was almost constant (6-10%) throughout the study period. Fungemia was highly associated with use of intravascular catheters, and some changes in clinical features were observed: 1) Candida albicans, C. parapsilosis and C. glabrata were the main isolates, and the number of fungal species showed a tendency to increase. 2) The percentage of patients over 65 years old increased from 36 to 50%. 3) The percentage of patients who were treated with anti-fungal agents and/or removal of catheter increased from 50 to 89 and to 86%. 4) The percentage of patients who died within 28 days after isolation of fungus decreased from 64 to 27%. The improved prognosis was thought to be due to the development of new anti-fungal agents and faster removal of intravascular catheter when infection was suspected.

Adolescent↗

PubMed1996

Diagnostic accuracy and safety of CT-guided percutaneous needle aspiration biopsy of the lung: comparison of small and large pulmonary nodules.

OBJECTIVE: The purpose of this study was to compare the diagnostic accuracy and safety of CT-guided percutaneous needle aspiration biopsy of pulmonary nodules less than or equal to 1.5 cm in diameter with those of nodules greater than 1.5 cm in diameter. MATERIALS AND METHODS: We retrospectively reviewed a consecutive series of 97 patients who underwent CT-guided percutaneous needle aspiration biopsy of a lung nodule and then surgical resection (n = 95) or autopsy (n = 2). By examining CT images, we classified 27 nodules as small ( < or = 1.5 cm) and 70 nodules as large ( > 1.5 cm). Diagnostic accuracy was calculated by comparing cytologic diagnoses based on biopsy with final diagnoses based on histologic findings from surgery or autopsy. Each case was reviewed for possible complications, including pneumothorax and chest tube placement. RESULTS: The diagnostic accuracy of CT-guided percutaneous needle aspiration biopsy of large nodules was 96%. The diagnostic accuracy for small nodules was 74%, a statistically significant difference (p < .05). The prevalences of pneumothorax in our population were nearly identical for small and large nodules (22 and 21%, respectively). The prevalence of chest tube placement in our population was approximately 2%. The prevalences of chest tube placement were 0% for small nodules and 3% for large nodules. CONCLUSION: CT-guided percutaneous needle aspiration biopsy is significantly less accurate for small pulmonary nodules than for large pulmonary nodules, but the complication rates for both are low.

Adult↗

PubMed1996

Prevalence of antibody to malignant catarrhal fever virus in wild and domestic ruminants by competitive-inhibition ELISA.

A competitive-inhibition ELISA (CI-ELISA), based on a monoclonal antibody to an epitope conserved among malignant catarrhal fever virus (MCFV) strains of both wildebeest and sheep origin, was used to determine the prevalence of antibody to MCFV in selected domestic and wild ruminants, both free-ranging and captive, from the USA. We evaluated 2528 sera from 14 species between 1990 and 1995, including 80 pronghorn antelope (Antilocapra americana), 339 bighorn sheep (Ovis canadensis), 103 biston (Bison bison), 17 black-tailed deer (Odocoileus hemionus columbianus), 395 domestic cattle (Bos taurus), 291 domestic goats (Capra hircus), 680 domestic sheep (Ovis ammon), 323 elk (Cervus elaphus), 41 llamas (Lama glama), 21 mouflon sheep (Ovis musimon), 54 mountain goats (Oreamnos americanus), 101 mule deer (Odocoileus hemionus), 20 muskox (Ovibos moschatus), and 63 white-tailed deer (Odocoileus virginianus). A high seroprevalence (37 to 62%) was observed in domestic sheep, domestic goats, muskox, and some bighorn sheep populations. Seroprevalence in these species was generally age-related: a very low seroprevalence was present in these animals under one year of age. A low seroprevalence (2% to 13%) was found in clinically-susceptible species such as domestic cattle, deer, elk and bison, supporting the concept that significant numbers of non-lethal infections occur among clinically susceptible ruminants.

Age Factors↗

PubMed1996

Effects of long-term cocaine exposure on spermatogenesis and fertility in peripubertal male rats.

PURPOSE: This study was conducted to investigate the effects of long-term administration of cocaine on spermatogenesis and fertility in adult male rats. MATERIALS AND METHODS: Thirty-day-old male Sprague-Dawley rats were given cocaine hydrochloride (15 mg./kg. body weight, corresponding to an average single dose for a heavy cocaine user) either daily or twice weekly (weekend group, cocaine given on Saturday and Sunday) and mated with pregnancy-proven female rats after 100 and 150 days of exposure to the drug. Pregnancy rates and litter birth weights were evaluated. Serum testosterone, follicle stimulating hormone and luteinizing hormone levels were measured in all adult rats. Morphologic analysis of the testis entailed the evaluation of quantitative and qualitative histologic parameters to assess the effect of cocaine on various stages of spermatogenesis. RESULTS: After 100 days of treatment, the rats receiving daily cocaine had a pregnancy rate of only 33% versus 86% for the controls (p < 0.05). In rats exposed to cocaine for 150 days the pregnancy rate was 50% compared with 100% for controls (p < 0.05). The birth weights of offspring from the group receiving daily cocaine was 10% less than that of controls (p < 0.05). The weight of the testis and epididymis was not affected by cocaine exposure. Morphometric analysis showed significant differences between the cocaine-treated groups (both the daily cocaine and twice weekly cocaine groups) and their respective controls. The mean diameter of seminiferous tubules in the daily and twice weekly cocaine groups was reduced when compared with their respective controls. These differences between treated groups and their controls were statistically significant (p < 0.05). Similarly the thickness of the germinal epithelium was less in the cocaine-treated groups than in the controls (p < 0.05). Degenerating cells were more numerous in both daily and twice weekly cocaine groups than the controls. Furthermore, the number of step VII spermatids was reduced in both daily and twice weekly cocaine groups, a difference that was statistically significant (p < 0.05). CONCLUSION: Our findings demonstrate that chronic administration of cocaine to peripubertal male rats has a profound effect on their testicular function. Even with twice weekly administration there was a significant adverse effect on spermatogenesis although this was not manifested by diminished fertility in this group. These findings confirm that chronic administration of cocaine to male rats can have a deleterious effect on spermatogenesis and fertility.

Animals↗

PubMed1996

Yeast ribosomal protein L32 recognizes an RNA G:U juxtaposition.

Yeast ribosomal protein L32, RPL32, specifically represses splicing by binding to a purine-rich asymmetric loop adjacent to the 5' splice site of its own transcript. A potential G:U pair closes the internal loop and the goal of the present study is to understand what features of the putative G:U pair are recognized by RPL32. Two RNA oligomers containing 10 and 13 nt were annealed to form a bimolecular stem-loop-stem protein-binding site. Protein binding to each of 16 sequence variants was examined using electrophoretic bandshift and filter-binding experiments. The proteins binds to only the duplex RNA and not to the individual oligomers, and the G:U pair is critical for full-strength binding. Mutational studies show that the duplex having a G:U has the highest protein affinity (Kd = 10 nM), followed by RNAs bearing G:A, C:C, U:A, U:C, or G:G. Duplexes containing the other possible pairs bind very weakly and Watson-Crick pairing does not favor protein binding. The G of the G:U is required for strong protein binding, but replacement by inosine reduces binding only modestly. Therefore, the minor groove guanine amino group is not a key protein recognition element. Both nucleotides of the pair influence the binding strength, but their contributions are in general not additive. These data imply that the G:U is probably paired and influences binding indirectly through its effect on the conformation of the RNA.

Base Composition↗

PubMed1996

[Site-directed mutagenesis of the gene of Echistatin Leu14-Lys15-Glu16].

In order to probe relationship of inhibition activity of platelet aggregation and RGD conformation beneficial to binding in Echistatin, we used the site-directed mutation technique to install another RGD sequence into one of irregular loops retaining a degree of conformational flexibility and substituting Leu-14, Lys-15, Glu-16 of (Leu-28) Echistatin. The mutant (Arg-14, Gly-15, Asp-16, Leu-28) Echistatin did not lose its inhibition activity of platelet aggregation; however, it showed at least as high activity as (Leu-28) Echistatin, or even a little higher than (Leu-28) Echistatin. This suggested that both RGD sequences inserted in one loop with a degree of conformational flexibility. The original RGD (Arg-24, Gly-25, Asp-26) motif projecting significantly from the surface of the scaffold or core might contribute synergistically to the function of inhibiting platelet aggregation induced by 10 mumol/ L ADP (final concentration). These results are useful in the elucidation of the relationship of structure and function of Echistatin-like disintegrins and GPIIb/IIIa-like integrins.

Amino Acid Sequence↗

PubMed1996

[Regeneration of free nerve endings and sensory corpuscles after implantation of nerve into the denervated skin in the monkey].

Two rhesus monkeys were used. Their fingers were denervated first and then the nerve was implanted into the denervated skin. The results showed that: (1) the process of regeneration of nerve fibers was similar to that of previous experiments in rabbits; (2) regeneration of nervous tissue included 2 kinds of sensory receptors with capsule-Meissner corpuscles and Merkel cell-dendrite complex; (3) the regenerative rate of Meissner corpuscles increased progressively and their morphology and structure became matured with elapse of time; (4) no regeneration of pacinian corpuscle was found in 6 months after nerve implantation; (5) Meissner corpuscles also regenerated in the transplanted glabrous skin.

Animals↗

PubMed1996

Neurobiological mechanisms of the meridian and the propagation of needle feeling along the meridian pathway.

The present experiments attempt to find the meridian phenomenon and how the needle feeling propagates along the given meridian channels. The neurobiological mechanisms of the meridian were studied with neuroelectrical recording from the motor neurons and CB-HRP retrograde histochemistry technique in both rats and cats. The results demonstrated that most, but not all, of alpha motor neurons supplying a muscle group of a given meridian were selectively activated by afferent inputs originating not only from homonymous or heterogeneous, but synergistic muscle, but also from the skin nerve overlying the muscle group of the homonymous meridian. However, the afferent inputs from the heterogeneous meridian have very weak or no effect. On the other hand, the labeled motor neurons supplying a given meridian muscles from a discrete longitudinal column with a definite bound in the lateral ventral horn. There are oriented dendro-dendristes projections between the labeled motor neurons. The characteristics of both selective responses of the motor neurons to afferent inputs and their neuro-anatomical arrangements in spinal cord offer neurobiological evidence for the meridian phenomenon.

Acupuncture Therapy↗

PubMed1996

[Reversal of malignant phenotype of cells of human pancreatic adenocarcinoma cell line by recombinant retroviral vector expressing antisense c-myc].

A recombinant retroviral vector expressing antisense c-myc was constructed. The recombinant virus DNA was packaged with packaging cell line PA317 cells by the calcium phosphate coprecipitation method. The virus supernatant was used to infect human pancreatic carcinoma cell line PC-2. After selection with G418, resistant colonies were obtained. Stable expression of retrovirus in both PA317 and PC-2 cells were confirmed by Northern blot hybridization. A down-regulation of endogenous c-myc was found in PC-2 cells infected with antisense c-myc construct. It was demonstrated that the antisense c-myc did inhibit the cell growth rate and 3H-TdR incorporation rate of PC-2 cells. The ability of colony formation in soft agar and tumorogenicity in nude mice of PC-2 cells were significantly suppressed by the antisense c-myc. The results implicate that recombinant retroviral vector containing antisense c-myc could inhibit target gene expression and partly reverse malignant phenotype of pancreatic adenocarcinoma cells.

Adenocarcinoma↗

PubMed1996

[Expression of LIF as autocrinal growth factor in human medulloblastomas].

In this study, in vivo and in vitro expression of LIF and its signal transducer genes, LIFR and gp130 in medulloblastoma cells and its role(s) in the cell proliferation were investigated by different approaches. The results revealed that 12 out of 13 cases examined were found to express LIF and more than 90% of the samples to express LIFR and gp130. Functional evaluation of LIF using Med-3 cells showed that the cell growth and DNA synthesis could be efficiently inhibited (P < 0.001) by neutralization of LIF bioactivity. Our data thus demonstrated the importance of LIF as autocrtinal growth factor in the proliferation of medulloblastoma cells and also implicated a potential new therapeutic approach for a better treatment of the tumors through blockage of LIF gene expression and/or ligand interaction.

Antigens, CD↗

PubMed1996

Microglia-derived macrophages in early multiple sclerosis plaques.

One of the characteristics of ongoing demyelination in multiple sclerosis (MS) is the accumulation of lipid-laden macrophages in active lesions. Little is known about the source of these macrophages in the early stages of plaque evolution as microglial-derived and haematogenous macrophages share morphological characteristics and most cell surface antigens. A key issue in understanding the pathogenesis of MS is the reliable identification of phagocytes capable of degrading myelin and presenting autoantigen to T cells at the onset of demyelination. Using a combination of histochemistry and immunocytochemistry, an average of 60% of EBM11+ phagocytes (EMBII is a pan-macrophage marker) in early active MS plaques, defined as lesions with myelin-containing phagocytes but no obvious parenchymal myelin loss around these cells, were judged to originate from microglia as they exhibited nucleoside diphosphatase activity, a microglial marker. Only 4-15% of EBM11+ phagocytes in these lesions exhibited non-specific esterase activity, an enzyme marker for monocytes and macrophages. In contrast, 30-80% of EBM11+ phagocytes in more advanced active plaques with partial or complete myelin loss in the parenchyma were non-specific esterase+. Lysosomal enzyme acid phosphatase activity was strongly exhibited by 90% of phagocytes in all active plaques and there was a significant correlation between numbers of acid phosphatase+ cells and oil red O+ foamy macrophages. The results indicate that microglia are the main population of phagocytes in the early stages of demyelination and may play an important role in the pathogenesis of MS.

Acid Phosphatase↗

PubMed1996

Detection of hepatitis C virus RNA using ligation-dependent polymerase chain reaction in formalin-fixed, paraffin-embedded liver tissues.

Reverse transcription polymerase chain reaction (RT-PCR) has been used to detect hepatitis C virus (HCV) sequences in liver tissue. However, RT-PCR has a variable detection sensitivity, especially on routinely processed formalin-fixed, paraffin-embedded (FFPE) specimens. RNA-RNA and RNA-protein cross-links formed during formalin fixation is the major limiting factor preventing reverse trans criptase from extending the primers. To overcome this problem, we applied the ligation-dependent PCR (LD-PCR) for the detection of HCV RNA in FFPE liver tissue. This method uses two capture probes for RNA isolation and two hemiprobes for the subsequent PCR. Despite cross-links, the capture probes and the hemiprobes are able to form hybrids with HCV RNAs released from the FFPE tissue. The hybrids are isolated through binding of the capture probes to paramagnetic beads. The hemiprobes are then ligated by a T4 DNA ligase to form a full probe that serves as a template for the Taq DNA polymerase. A total of 22 FFPE liver specimens, 21 with hepatocellular carcinoma (HCC) and 1 with biliary cirrhosis secondary to bile duct atresia were selected for this study, of which 13 patients were HCV seropositive and 9 seronegative. HCV RNA was detectable by ID-PCR from all 13 HCV-seropositive HCCs and from 5 of 8 HCV-seronegative HCCs but not from the HCV-seronegative liver with biliary atresia. By contrast, RT-PCR detected HCV sequences in only 5 of the HCV-sero-positive and in 1 of the HCV-seronegative HCCs. To resolve the discordance between the LD-PCR and RT-PCR results, RT-PCR was performed on frozen liver tissue of the discrepant specimens, which confirmed the LD-PCR positive results. In conclusion, LD-PCR is a more sensitive method than RT-PCR for the detection of HCV sequences in routinely processed liver tissues. A high rate of HCV infection (86%) is found in HCC specimens, indicating a previously underestimated role of HCV in HCC pathogenesis.

Base Sequence↗

PubMed1996

Micellar electrokinetic capillary chromatographic analysis of platelet activating factor in human blood by indirect ultraviolet detection.

In this paper, 1-O-hexadecyl and 1-O-octadecyl-2-acetyl-sn-glycero-3- phosphorylcholine (C16-AGEPC and C18-AGEPC) in the platelet activating factor of human blood were analyzed by micellar electrokinetic capillary chromatography (MECC) with indirect ultraviolet absorption detection at 254 nm. The optimum running buffer for the separation contained 50 mmol/l sodium dodecy sulphate, 20 mmol/l potassium hydrogen phthalate, 10 mmol/l borax and 3 mol/l urea (pH 6.8). The separation was completed within 10 min. The detection limits of C16-AGEPC and C18-AGEPC were the same, i.e. 60 ng/ml (k = 3). The analytical precision (n = 6) was 2.8-3.0% and 1.4-1.7% for the determination (peak height mode) and for the measurement of the migration times, respectively. The application of this method to the clinical samples was demonstrated.

Borates↗

PubMed1996

Treating tuberculous pleurisy with effusion by artificial pneumothorax.

The efficacy of artificial pneumothorax therapy was evaluated in subjects with tuberculous pleurisy with effusion. The patients (57 cases) were divided into two groups at random: 30 cases in the control group and 27 cases in the group under treatment. They were all given standard treatment with antituberculous drugs drawing liquid accumulated and injecting antituberculous drugs and corticosteroids into their intrapleural cavity. In addition, the treating group received artificial pneumothorax to enhance the treatment efficacy. The frequency and amount of liquid drawn in the treating group were obviously less than those in the control group. Time necessary to draw all the liquid was substantially shortened in the former case with a higher degree of efficiency (92.59%) than that of the latter (83.33%). We also found that the artificial pneumothorax could raise the intrapleural pressure of 2 to 4 cm H2O, reduce leakage in parietal pleura and evidently increase the absorption in visceral pleura. The results suggest that artificial pneumothorax can reduce the liquid leakage and accelerate absorption of the liquid in thorax. As the two layers of pleura can be isolated by the air in thorax, the occurrence rate of pleural adhesion can be cut down. Hence, it is an effective assistant therapy for tuberculous pleurisy with effusion.

Adolescent↗

PubMed1996

Brain aggrecan.

During development, the extracellular matrix (ECM) is a complex dynamic structure whose components and organization help to establish the requisite position and state of differentiation. Until recently, the large chondroitin sulfate proteoglycan, aggrecan, has been localized predominantly to skeletal tissue and considered a hallmark of cartilage differentiation. We have identified the presence of aggrecan in two other highly differentiated systems, brain and notochord, with clearly distinct expression patterns. In chick cartilage, aggrecan starts to be expressed at embryonic day 5 in limb rudiments, continues through the entire period of chondrocyte development, and remains a biochemical marker of the cartilage phenotype thereafter. In brain, aggrecan has a very low level of expression beginning at day 7, increases up to day 13, markedly decreases after day 16, and is not expressed posthatching. This pattern coincides with migration and establishment of neuronal nuclei in the chick telencephalon and has been proposed to be a component of the migration arrest mechanism. In very primitive embryos, aggrecan is detected as early as stage 16 in the notochord, long before chondrogenesis occurs, is then expressed up to day 5 and decreases thereafter. The expression of aggrecan occurs during the time of active neural crest migration and through the onset of sclerotomal differentiation, and correlates with the notochords' ability to inhibit neural crest cell migration. Animal models defective in aggrecan biosynthesis have been invaluable in delineating these functions. In addition we have characterized these proteoglycans by chemical, biosynthetic, and molecular analyses. Although significant post-translation differences distinguish the cell-specific aggrecan species, their core proteins are the products of a single gene. Our findings of the expression of the same gene (aggrecan) in multiple ontogenously unrelated differentiating tissue systems and at different times over the developmental life of an organism provide an elegant model system to study the regulation and interplay in expression of that gene, as well as the effect of alterations in that single gene simultaneously in several developing programs.

Aggrecans↗

PubMed1996

Expression of TGF-beta 1, PDGF and IGF-1 mRNA in lung of bleomycin-A5-induced pulmonary fibrosis in rats.

OBJECTIVE: To investigate the influence of alveolar macrophages (AMs), fibroblasts and interstitial cells on development of lung fibrosis, and the interactions among TGF-beta 1 PDGF and IGF-1 and these cytokines-effects on lung fibrosis. MATERIAL AND METHODS: Expressions of TGF-beta 1, PDGF and IGF-1 mRNA in the lung cells and lung tissues in different stages of Bleomycin-A5-induced pulmonary fibrosis in rats were studied through Northern hybridization. RESULTS: The expressions of TGF-beta 1 and PDGF mRNA reached their peaks in AMs of pulmonary fibrosis in rats on the 7th day after Bleomycin-A5 instillation. It was similar with that in the lung tissues. IGF-1 mRNA remained relatively stable in AMs during the course. PDGF and IGF-1 mRNA increased gradually in fibroblasts, and reached the highest expressions in the interstitial cells. There was almost no TGF-beta 1 mRNA expression in all groups of fibroblasts. CONCLUSIONS: AMs are the main sources of TGF-beta 1 and PDGF in the lung tissues with fibrosis induced by Bleomycin-A5 AMs are activated in the first weekend and secrete TGF-beta 1 and PDGF to promote fibroblasts proliferation and fibrosis. As fibrosis developed, fibroblasts have established PDGF and IGF-1 autocrine and these three cytokines paracrine nets combined with the interstitial cells to promote lung fibrosis.

Animals↗

PubMed1996

A scanning electron microscopic study of trabeculae in osteoporotic femoral head.

OBJECTIVE: To investigate osteoclastic resorption in trabeculae of osteoporotic femoral head. METHODS: Osteoporotic femoral heads were collected from 7 aged women with an average age of 72.4 years, who underwent endoprosthetic replacement for intracapsular hip fracture. Femoral head trabeculae from 3 young adults killed in traffic accidents served as control. The two types of specimens were processed and studied under scanning electron microscope. RESULTS: The trabeculae of femoral head formed round or roundish arch structure. The columnar trabeculae of femoral head in the aged women showed overt osteoclastic resorption, manifested in thinning, tapering and perforation, resulting in formation of icicle-like trabeculae, which then became rounded, lost height and eventually turned into small tubercle. As a result, the inter-trabecular space enlarged markedly. Under high magnification, the trabeculae could be discerned oval, narrow oval or spindle-shaped. Howship resorption lacunae, which varied in size, depth and content, but all revealed punched-out margin. During bone resorption, the inorganic and organic components were successively resorbed. In the Howship lacunae and surrounding areas, newly formed collagen fibrils and bone tissues emerged, signifying reversal and new bone formation phases after bone resorption phase. CONCLUSION: Osteoclastic resorption markedly compromises the structural integrity and strength of the trabeculae of the arch structure of the femoral head in the aged women.

Age Factors↗