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Biomedical subjects

L C Lu

Publications and source records attributed to L C Lu.

9 recordsLinked to original sources
PubMed1995

Sensory neuropeptides modulate cigarette smoke-induced decrease in neutral endopeptidase activity in guinea pig airways.

Cigarette smoke (CS) inhalation stimulates C-fibers to release sensory neuropeptides which mediate airway reflex responses to prevent irritants from entering the lower airways. When CS is inhaled via the upper airways, these airway defense responses may modulate the effect of CS on airway NEP activity and related airway hyperresponsiveness. To examine this possibility, we exposed guinea pigs to 1:10 diluted mid-tar cigarette smoke 100 puffs per day for 7 days and recorded pulmonary resistance of cumulative doses of neurokinin A (NKA, 10(-12)-10(-8) mol/kg, i.v.) or methacholine (Mch, 1-50 micrograms/kg, i.v.). NEP activity in the tracheobronchi was measured using fluorometric assay. Exposure of CS alone failed to alter the dose-response to NKA or Mch compared with air control. NEP activity in the airways after CS exposure was slightly but significantly lower than that of air control. Capsaicin pretreatment 1 week before CS exposure significantly shifted the dose-response curves of NKA, but not Mch, to the left and decreased NEP activity in the airways to a greater extent compared with CS exposure alone group. Capsaicin pretreatment alone failed to alter the responsiveness to NKA or NEP activity. CS also induced a significant increase in neutrophil counts in airways. Capsaicin pretreatment enhanced the effect of CS on neutrophil recruitment. We conclude that sensory neuropeptides may have a protective role in modulation of airways NEP activity downregulation induced by CS, probably by preventing CS from entering the lower airways or the chronic release of sensory neuropeptides induced by CS providing increased amount of substrata for NEP upregulation, and therefore modify the direct effect of CS on NEP activity and related airway hyperresponsiveness.

Airway Resistance↗
PubMed1989

Experimental vertical transmission of Japanese encephalitis virus by Culex tritaeniorhynchus and other mosquitoes.

Vertical transmission of Japanese encephalitis virus to the F1 adult stage was demonstrated in Culex tritaeniorhynchus, Cx. annulus, Cx. quinquefasciatus, and Armigeres subalbatus. Transmission to the F1 larval stage was demonstrated in Cx. pipiens, Aedes vexans, Ae. alcasidi, and A. flavus. In Cx. tritaeniorhynchus, vertical transmission rates (the percentage of parent females transmitting to progeny) varied (12-100%). Filial infection rates (the percentage of progeny infected) for a given mosquito virus combination were markedly affected by the interval of time between parental infection and oviposition, suggesting that vertical infection was not transovarial in nature but occurred at oviposition. Filial infection rates for Cx. tritaeniorhynchus also varied widely by family and, as measured in F1 larvae, rates in excess of 20% were observed in a family. Filial infection rates in Cx. tritaeniorhynchus F1 adults were about 4 times lower than those in larvae. Japanese encephalitis virus was sexually transmitted from male to female Cx. tritaeniorhynchus.

Animals↗
PubMed1989

A longitudinal study of the prevalence of Japanese encephalitis virus in adult and larval Culex tritaeniorhynchus mosquitoes in northern Taiwan.

Adult females and larvae of Culex tritaeniorhynchus were collected year-round for 3 1/2 years at a site near Taipei, Taiwan. One hundred sixty-four isolates of Japanese encephalitis (JE) virus were obtained from approximately 142,000 adult females and 1 isolate of the virus was obtained from approximately 382,000 larvae. Virus was recovered from adult females every year, except the first, beginning in May. The single larval isolate was from specimens collected in June. The vertical transmission of JE virus in Cx. tritaeniorhynchus as a possible inter-epidemic viral survival mechanism is examined.

Animals↗
PubMed1989

The relation between Campylobacter pylori and inflammatory cell infiltration of antral mucosa in patients with dyspepsia.

In order to understand the relation between the prevalence of Campylobacter pylori and the severity of gastritis, we conducted a survey of 166 randomly selected dyspeptic patients. The presence of C. pylori on the antral mucosa was aseptically determined by both urease and bacterial culture tests. Specimens of antral mucosa were obtained for pathologic gradings of inflammation: active gastritis, mononuclear cell infiltration C0 (nil) to C3 (lymphoid follicle); presence or absence of intestinal metaplasia. Pathologically, chronic gastritis was invariably present in almost all patients with dyspepsia: three-fourths of them showed evidence of active gastritis, one-third showed intestinal metaplasia. Half of the dyspeptic individuals had C. pylori colonization. The results suggest that the prevalence of C. pylori was closely related to the different grades of active gastritis; neither the different grades of chronic gastritis nor intestinal metaplasia affected the prevalence of C. pylori on gastric mucosa. We conclude from this study that C. pylori is closely related to active chronic gastritis because of the common presence of chronic gastritis in patients with dyspepsia.

Adult↗
PubMedDate not supplied

Medical treatment of duodenal ulcer: acid inhibition or Helicobacter pylori eradication?

To ascertain whether acid inhibition or Helicobacter pylori (HP) colonization is the decisive factor in the healing of duodenal ulcer, we treated 54 patients with famotidine and carried out long-term follow-up. Helicobacter pylori colonization was found in 70.4% of patients before treatment. There were no differences in the pre-treatment characteristics between patients with HP positive or HP negative ulcers. The 4-week and 8-week healing rates after famotidine treatment were 72.5% and 82.4% respectively. No difference in HP colonization was found between patients with ulcer healed and those with ulcer not healed (78.4% vs 64.3% at 4th week and 77.3% vs 71.4% at 8th week, P greater than 0.05). In patients with ulcer healed at 4th week, the intragastric pH was raised significantly and the antral acute inflammation was less severe than those with ulcer not healed. Ulcer recurrence was found in 76.9% of patients within 1 year, but there was no difference in ulcer recurrence between the patients with positive or negative HP colonization at the time of ulcer healing. Our results suggest that duodenal ulcer healing and recurrence are closely related to acid inhibition rather than to HP colonization.

Duodenal Ulcer↗