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L H Hu

Publications and source records attributed to L H Hu.

At least 19 recordsLinked to original sources
PubMed2006

Modeling fire-induced smoke spread and carbon monoxide transportation in a long channel: Fire Dynamics Simulator comparisons with measured data.

Smoke and toxic gases, such as carbon monoxide, are the most fatal factors in fires. This paper models fire-induced smoke spread and carbon monoxide transportation in an 88m long channel by Fire Dynamics Simulator (FDS) with large eddy simulation (LES). FDS is now a well-founded fire dynamics computational fluid dynamic (CFD) program, which was developed by National Institute of Standards and Technology (NIST). Two full scale experiments with fire sizes of 0.75 and 1.6MW were conducted in this channel to validate the program. The spread of the fire-induced smoke flow together with the smoke temperature distribution along the channel, and the carbon monoxide concentration at an assigned position were measured. The FDS simulation results were compared with experimental data with fairly good agreement demonstrated. The validation work is then extended to numerically study the carbon monoxide concentration distribution, both vertically and longitudinally, in this long channel. Results showed that carbon monoxide concentration increase linearly with the height above the floor and decreases exponentially with the distance away from the fire source.

Carbon Monoxide↗
PubMed2001

Benzopyran derivatives from Mallotus apelta.

From the leaves of Mallotus apelta, seven benzopyran compounds were obtained and their structures were determined using spectroscopic methods. One showed moderate antibiotic activity against Micrococcus lutens.

Benzopyrans↗
PubMed2001

Three new hyperforin analogues from Hypericum perforatum.

Three new analogues of hyperforin (1), pyrano[7,28-b]hyperforin (2), (2R,3R,4S,6R)-6-methoxycarbonyl-3-methyl-4,6-di(3-methyl-2-butenyl)-2-(2-methyl-1-oxopropyl)-3-(4-methyl-3-pentenyl)cyclohexanone (3), and (2R,3R,4S,6S)-3-methyl-4,6-di(3-methyl-2-butenyl)-2-(2-methyl-1-oxopropyl)-3-(4-methyl-3-pentenyl)cyclohexanone (4), were isolated from the aerial parts of Hypericum perforatum (St. John's wort). The structures of 2-4 were elucidated by spectroscopic methods.

Anti-Bacterial Agents↗
PubMed2000

Phloroglucinol derivatives from Hypericum japonicum.

The isolation and identification of a new phloroglucinol derivative (2), a diterpenol (4), together with the known compounds flavesone (1) and sarothralen B (3), from the aerial parts of Hypericum japonicum are reported. Their structures were established by extensive spectral analysis and the structure of (3) has also been confirmed by a single crystal X-ray determination.

Crystallography, X-Ray↗
PubMed2000

New products from alkali fusion of ginkgolides A and B.

Alkali fusion of ginkgolides A and B has afforded five unexpected products 3-7. Their structures were established from their spectral data and chemical reactions. They were evaluated for their in vitro activity to inhibit the platelet-activating factor-induced aggregation of rabbit platelets and show less potency than ginkgolides A and B.

Animals↗
PubMed1999

Cytotoxic polyprenylated benzoylphloroglucinol derivatives with an unusual adamantyl skeleton from Hypericum sampsonii (Guttiferae).

[formula: see text] The structures of sampsoniones I and J, isolated from the aerial parts of the Chinese medicinal plant Hypericum sampsonii, have been elucidated by detailed spectral analysis. They are complex adamantyl derivatives, and sampsonione I is the first polyprenylated benzoylphloroglucinol derivative with the unique caged tetracyclo[7.3.1.1.0]tetradecane-2,12,14-trione skeleton. Cytotoxic sampsonione I has also been obtained by the biomimetic transformation of sampsonione J.

Adamantane↗
PubMed1998

A 3D-QSAR study on ginkgolides and their analogues with comparative molecular field analysis.

Comparative molecular field analysis (CoMFA), a three-dimensional quantitative structure-activity relationship (3D-QSAR) paradigm was used to study the correlation between the physicochemical properties and the in vitro bioactivities of ginkgolide analogues. The correlation derived from CoMFA analysis has a good predictive capability. Based on the result of CoMFA analysis, we designed some compounds. Pharmacological assay indicated that three of these new designed compounds are 2 and 4 times more potent than that of ginkgolides.

Diterpenes↗
PubMed1997

Consistent allelic loss on mouse chromosome 7 distal to tyrosinase in 4-nitroquinoline-1-oxide-induced oral cavity tumors with loss of heterozygosity at Ha-ras-1.

We have previously shown that all CBA/J mice exposed to 4-nitroquinoline-1-oxide (4NQO) eventually develop oral cavity squamous cell carcinomas, and two-thirds of these tumors have Ha-ras-1 (Hras1) point mutations at codon 12. Half of the tumors with Hras1 mutations have loss of heterozygosity (LOH) at Hras1. In the study reported here, seven tumors with LOH at Hras1, six heterozygous for Hras1, and six without Hras1 mutations were analyzed to define the extent of LOH on chromosome (Chr) 7. Microsatellite polymorphisms present in CBA/J mice were used as informative allelic markers. Tumors with LOH at Hras1 showed consistent allelic loss at the distal portion of Chr 7. The boundary of allelic loss lay between the tyrosinase and hemoglobin beta chain loci, which are 6 cM apart. None of the tumors that remained heterozygous for Hras1 or had no Hras1 mutations had evidence of chromosomal loss involving Chr 7. Because LOH was only detected in advanced lesions long after exposure to 4NQO had ceased, we presume that the chromosomal alterations by which LOH occurred were independent of the carcinogen exposure. The development of LOH in only half of the tumors with Hras1 point mutations suggests that LOH was not caused by the initial Hras1 point mutation but was a highly selected event during tumorigenesis.

4-Nitroquinoline-1-oxide↗
PubMed1996

Frequent DNA polymorphisms exist in inbred CBA/J and C3H/HeN mice.

Although occasional DNA polymorphisms have been observed in inbred mice, CBA/J and C3H/HeN mice have two microsatellite alleles at over 1/3 of microsatellite loci tested. Since DNA polymorphisms were not detected in DBA/2J, C57BL/6J, and BALB/cJ, the frequency of microsatellite polymorphisms appears to be strain specific. Thus, genetic studies in inbred mice require testing for preexisting polymorphisms. The polymorphisms detected in CBA/J mice appear to be stable and do not represent microsatellite instability or a mutator phenotype. Somatic mosaicism was not observed and no more than two alleles were detected per locus. CBA/J propagated only by brother-sister mating maintained seven of eight polymorphisms over 5 years. These data suggest that the polymorphisms are due to an inherited trait and that the pattern of inheritance is not due to Mendelian distribution. As breeding analysis was not performed, the pattern of allelic inheritance is unknown.

Animals↗
PubMed1996

Distinct regions of thyroglobulin control the proliferation and suppression of thyroid-specific lymphocytes in obese strain chickens.

The effect of thyroglobulin (Tg)iodination on the proliferation and suppression of thyroid-specific lymphocytes was examined in vivo in the obese strain (OS) and Cornell strain chicken models of autoimmune thyroiditis. Spleen cells from OS chickens were able to transfer disease to Cornell strain recipients. The ability to transfer disease was markedly reduced if the donors were raised on an iodine-depleting regimen. This deficiency was corrected by immunization of donor chickens with iodinated Tg. Immunization with low iodine Tg was ineffective. Neonatal tolerance induction with either iodinated or low iodine Tg reduced thyroiditis in 2-week-old OS chickens. Spleen cells from these tolerized chickens transferred to 4-day-old OS chickens were less thyroiditogenic. These results indicate that thyroid autoreactive cells are responsive to iodinated Tg, but not to low iodine Tg. Both of the Tg preparations, however, can induce tolerance to the disease. We conclude that distinct regions of the Tg molecule regulate the proliferation and suppression of thyroid-reactive lymphocytes, respectively. Only the former is dependent on the iodination of Tg. These results emphasize the importance of Tg as a self-antigen and provide one mechanism by which iodine may induce autoimmune thyroiditis.

Animals↗
PubMed1993

[Intrathecal meperidine attenuates shivering induced by spinal anesthesia].

Shivering is a common and complex phenomenon that occurs in many patients during spinal anesthesia. Shivering can increase oxygen consumption up to 500 per cent which may be detrimental to patients with decreased myocardial reserve. The metabolic costs and cardiorespiratory consequences of shivering are important particularly for patients with anemia, coronary arterial disease, cardiopulmonary insufficient, debilitated status or are elderly. We studied whether intrathecal meperidine could prevent shivering after spinal anesthesia. 60 patients with ASA class I-II were divided into intrathecal meperidine group (Group I) (n = 30) and control group (Group II) (n = 30). Group I received spinal tetracaine 12-16 mg with meperidine 0.2 mg/kg and Group II received spinal tetracaine 12-16 mg without meperidine. During operation the highest level of spinal anesthesia, ambient and rectal temperatures, blood pressure (BP) and heart rate (HR), presence or absence of shivering, intensity of shivering in both groups were recorded. Close observation for side effects was given post-operatively. There was a significant reduction (p < .005) in incidence of shivering in group I patients (16.7%) when compared with group II (56.7%). There was no or less side effects observed with other neuraxial opioids except nausea. We concluded that intrathecal meperidine could suppress shivering induced by spinal anesthesia.

Adult↗
PubMed1992

[Intramuscular meperidine for the prevention of shivering in spinal anesthesia].

Intravenous meperidine 25mg has been employed effectively to treat shivering following regional anesthesia and general anesthesia. The study was designed to evaluate the effectiveness of intramuscular meperidine for the prevention of shivering in spinal anesthesia. The series consisted of 60 patients who were divided into 2 groups with 30 patients in each, undergoing lower abdominal or lower extremity surgery. All patients were given diazepam 0.1mg/kg i.v. for anxiolysis when they came to the operating room. In a double blind and randomized fashion, patients in the study (meperidine) group received meperidine 25mg IM (= 0.5ml). In the control group 0.9% N/S 0.5ml IM was given instead. All patients received spinal anesthesia 15 minutes later. Measurement of the levels of sensory loss to pinprick was made. The ambient temperature and the rectal temperature were continuously monitored to evaluate the effect of the change in body temperature on shivering during operation. The degree and the occurrence of shivering were carefully evaluated and recorded by a blind-trust observer. There was no significant difference in maximal analgesic level, ambient temperature and change of rectal temperature during operation between the groups. Shivering occurred in 17 patients (56.7%) in the saline group with an onset time of 7.9 +/- 2.5min following spinal anesthesia. In the meperidine group, shivering occurred only in 3 patients (10%) with an onset time of 54 +/- 29.5min after spinal anesthesia. There was a significantly lower incidence of shivering in the meperidine group than in the saline group (p < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1990

Serial adoptive transfer of experimental autoimmune uveoretinitis in rats.

Experimental autoimmune uveoretinitis (EAU) and pinealitis induced by an interphotoreceptor retinoid-binding protein (IRBP)-derived peptide (R4) was serially transferred into naive recipient rats, using spleen cells from recipients of previous "orders" of transfer. The cells initiating the disease in recipients of the first order were either lymph node cells from rats immunized against peptide R4, or lymphocytes of a cell line specific toward this peptide. The serial transfer was successfully carried out through as many as four orders of sequential recipients.

Amino Acid Sequence↗
PubMed1989

Identification of an immunodominant and highly immunopathogenic determinant in the retinal interphotoreceptor retinoid-binding protein (IRBP).

Interphotoreceptor retinoid-binding protein (IRBP), a glycoprotein specific for the retina and pineal gland, induces inflammatory changes in these two organs in immunized animals. We report here on the identification of an immunodominant determinant of bovine IRBP that is highly immunogenic and immunopathogenic in the Lewis rat. The peptide, which comprises the sequence 1169-1191 of bovine IRBP, was shown to be immunodominant by its capacity to stimulate lymphocytes sensitized against whole IRBP. A comparison was made between peptide 1169-1191 and another peptide, 1158-1180, which is nondominant but is immunogenic and immunopathogenic in the Lewis rat. Peptide 1169-1191 was found to be superior in its immunological capacities; the minimal dose of 1169-1191 needed to induce cellular immune response or disease in Lewis rats (0.02-0.1 nmol/rat) is congruent to 1,000 times smaller than that of 1158-1180. In addition, unlike the ocular disease induced by 1158-1180, the disease produced by 1169-1191 resembled that induced by whole IRBP in its kinetics and histopathological features. The immunological activity of 1169-1191 in the Lewis rat was localized to the 10 residues at the COOH terminus; no such activity was exhibited by the truncated peptide 1169-1188, which comprises the 20 residues at the NH2 terminus of the full peptide. The usefulness of this unique experimental system in analyzing the role of immunodominance in peptide immunogenicity and immunopathogenicity is underscored.

Amino Acid Sequence↗