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Biomedical subjects

L H Yu

Publications and source records attributed to L H Yu.

11 recordsLinked to original sources
PubMed2001

Characterization of a high-gain harmonic-generation free-electron laser at saturation.

We report on an experimental investigation characterizing the output of a high-gain harmonic-generation (HGHG) free-electron laser (FEL) at saturation. A seed CO2 laser at a wavelength of 10.6 microm was used to generate amplified FEL output at 5.3 microm. Measurement of the frequency spectrum, pulse duration, and correlation length of the 5.3 microm output verified that the light is longitudinally coherent. Investigation of the electron energy distribution and output harmonic energies provides evidence for saturated HGHG FEL operation.

Journal Article↗
PubMed2000

Inverted papilloma.

BACKGROUND: Inverted papilloma, a benign sinonasal lesion, constitutes 0.5% to 4% of all nasal tumors. Its local aggressiveness, high recurrence rate, association with malignancy or malignant transformation, and tendency toward multicentricity lead most physicians to advocate radical surgery. Nonetheless, conservative surgery is effective for selected patients with limited disease. This study was done to reassess the efficacy of both radical and conservative surgery. METHODS: The records of all patients with the diagnosis of inverted papilloma treated at the Taipei Veterans General Hospital between January 1986 and October 1998 were collected. A minimal follow-up period of 12 months was required for inclusion in the study. Clinical manifestations, radiologic findings, methods of treatment, pathology reports and recurrence rates were all retrospectively reviewed. RESULTS: Sixty patients with an average age at diagnosis of 58 years were studied. The follow-up period ranged from 12 to 195 months, with a mean of 43 months. The most common presenting symptom was unilateral nasal obstruction. The duration of symptoms ranged from one month to 30 years, with a mean of 36 months. The lateral wall and middle meatus were the most commonly involved sites. Bone erosion and intracranial or intraorbital extension were observed in some patients. Medial maxillectomy was the most common surgical treatment, followed by functional endoscopic sinus surgery and the Caldwell-Luc operation. The overall recurrence rate was 23%, with an average interval from initial treatment to recurrence of 42 months (range, 2-93 months). The recurrence rates for the two groups undergoing medial maxillectomy and conservative surgery were 16% and 27%, respectively. CONCLUSIONS: Early diagnosis relies on high suspicion and biopsy. The treatment modality is related to the location and extent of the disease, which is assessed by preoperative imaging studies. Any tumor with extensive involvement of the sinuses or inaccessibility to the endoscope should be treated with traditional medial maxillectomy for best control. The endoscopic technique is good for preoperative biopsy and follow-up.

Adult↗
PubMed1999

Malignant otitis externa.

BACKGROUND: Malignant otitis externa is an infrequent but severe infection of the external auditory canal, most often affecting elderly diabetic patients. Early diagnosis is necessary due to its high morbidity and mortality. METHODS: From 1990 to 1997, all patients with malignant otitis externa at the Veterans General Hospital-Taipei were reviewed retrospectively. The clinical features and the strategy of diagnosis and treatment are discussed. RESULTS: Twelve patients with an average age of 65.3 years were included. Eleven of these patients were diabetic. All had the presenting symptoms of otalgia and otorrhea at diagnosis. Bacterial cultures grew Pseudomonas aeruginosa in eight patients and methicillin-resistant Staphylococcus aureus in four patients. The mean duration of admission was 82 days. Appropriate antibiotics were given according to the results of bacterial culture and sensitivity test. 99Technetium scans and 67gallium scans were performed to evaluate the extent of involvement and monitor the effects of treatment. Eventually, four patients died due to renal failure, meningitis, pneumonia and upper gastrointestinal bleeding, respectively. CONCLUSIONS: Malignant otitis externa is a life-threatening infection arising from the external auditory canal. A high degree of suspicion for malignant otitis externa is mandatory. Vigorous local and systemic antimicrobial treatment should be initiated early in the course of the disease to achieve a satisfactory outcome. 99Technetium and 67gallium scans are important for the diagnosis and evaluation of the treatment results.

Adult↗
PubMed1998

A novel MT gene of rice plants is strongly expressed in the node portion of the stem.

We identified a cDNA encoding a metallothionein (MT)-like protein from a cDNA library of rice endosperm. This cDNA (ricMT) encoded an open reading frame of 80 amino acids, with two cysteine-rich domains at the amino-terminus and carboxy-terminus, respectively. The deduced amino acid sequence was homologous to those of class I MT-like proteins. Southern blot analysis revealed that the gene exists at one locus in the rice genome. Northern blot analysis with rice seedlings showed that the transcript level in shoots was elevated by the addition of metal ions, such as Cu, Zn, Cd, Fe, Pb and A1, whereas in roots it was reduced in the presence of metal ions other than copper. The expression level of ricMT in mature rice plants was extremely high in stems relative to leaf blades, leaf sheaths, endosperm and roots. In the first nodes, the yield of the transcript was 150-times higher than that in leaf blades. These results suggest that ricMT protein may play an important role in the metabolism of metal elements in the stem.

Amino Acid Sequence↗
PubMed1998

Tympanoplasty for pars flaccida.

BACKGROUND: The formation of a retraction pocket of the pars flaccida remains a difficult problem for otologists to treat. It may lead to ossicular erosion and the development of a cholesteatoma, especially when the pocket is adherent to the malleus neck. We designed a new method of surgery for the treatment of small attic cholesteatomas. METHODS: From 1986 to 1996, 20 patients with a retraction pocket of the pars flaccida or a small attic cholesteatoma underwent surgery as described below. The complete lesion was removed after widening the posterior-superior bony external ear canal wall and placing pieces of conchal cartilage (usually less than 10 pieces, according to their scutum defect) lateral to the malleus neck or incus. The temporalis fascia was then laid. RESULTS: The average follow-up period was 32 months. The paired t-test was used to compare the results of preoperative and postoperative air conduction and air-bone gap. The preoperative average air conduction was 31.17 dB and the air-bone gap was 15.09 dB. The postoperative average air conduction was 20.66 dB and the air-bone gap was 3.09 dB. The difference between preoperative and postoperative measurements was considered significant (p < 0.05). No recurrent retraction pockets or cholesteatomas were noted during follow-up. CONCLUSIONS: Tympanoplasty for correction of a retraction pocket of the pars flaccida can prevent further attic retraction and the development of cholesteatomas. Postoperative hearing results were also encouraging.

Adolescent↗
PubMed1998

Effects of acute brainstem compression on auditory brainstem response in the guinea pig.

BACKGROUND: The purpose of this study was to establish the norm for parameters of auditory brainstem response (ABR) in the guinea pig and to investigate if acute brainstem compression results in significant changes to these parameters. METHODS: Thirty-six guinea pigs with positive Preyer's reflex were anesthetized. A craniectomy was performed to remove the right occipital bone and the dura mater was opened to expose the brain, cerebellum and cerebellopontine angle (CPA). A small inflatable balloon was placed into the CPA precisely and slowly. ABR was recorded before incision of the skin as a baseline value, after placement and after inflation of the balloon with water at 0.1-ml intervals. RESULTS: Five stable peaks were recorded in 27 experimental animals. When the balloon was inflated with 0.1 ml water, the absolute latency (AL) of peaks IV and V and the interpeak latency (IPL) of peaks III and IV, and IV and V were prolonged. The amplitude ratios (AR) of peaks II, III, IV and V to peak I decreased. Inflation of the balloon with 0.2 ml of water caused further elongation of ALs of peaks IV and V and decreases in each AR. When the balloon volume increased to 0.3 ml, peak V became unrecognizable and peaks III and IV showed significant elongation of AL; peaks I and II did not show significant change in ALs. Further increase of the balloon volume to 0.4 ml resulted in disappearance of peaks III, IV and V; AL of peak II was also elongated. However, the amplitude and AL of peak I remained unchanged. Similar changes were observed in IPLs. CONCLUSIONS: This study establishes the norm of parameters of ABR in guinea pigs and demonstrates that acute brainstem compression causes elongation of ALs and IPLs of peaks II, III, IV and V. This suggests that peaks II, III, IV and V come from the brainstem and that peak I is not generated from the brainstem in the guinea pig.

Animals↗
PubMed1997

[Effects of semen Cuscutae, rhizoma Curculiginis, radix Morindae officinalis on human spermatozoan's motility and membrane function in vitro].

OBJECTIVE: To observe the effects of Semen Cuscutae (SC), Rhizoma Curculiginis (RC) and Radix Morindae Officinalis (RMO) on human sperm motility in vitro and cytomembrane function. METHODS: Compare the sperm motility of the above-mentioned medicinal plants with modified Tyrode's solution (MTS) and MTS added caffeine in vitro. Human spermatozoa were incubated with decoctions of medicinal plant at various concentrations in 37 degrees C for 30 minutes. The motility of sperm was evaluated by the sperm capillary penetrating test, sperm speed test and sperm activity index calculations. The spermatozoa membrane function was evaluated by spermatozoal hypo-osmotic swelling test together with eosin staining methods. RESULTS: The sperm motility improved markedly and sperm membrane function became more stabilized after incubation, the SC had best effect, RC took second place, RMO was relatively poor. CONCLUSIONS: SC decoction is an effective promoting preparation for sperm motility and the membrane function stabilized. Therefore, SC may be beneficial in treating male sterility and may raise success rate in artificial insemination.

Drugs, Chinese Herbal↗
PubMed1991

[Effect of herbal prostatitis decoction on experimental prostatitis in rats].

Herbal prostatitis decoction is a great effective prescription to treat chronic prostatitis in promoting the blood circulation and relieving the stasis. The authors had succeeded in making rats experimental fibrous proliferation type prostatitis models by using xiaozhiling injection method. Rats were divided into two groups: the decoction-given group (DG) and the water-given group (WG). Microscopically, both inflammatory cell infiltration and fibroblast proliferation of interstitial tissue in the DG were slight than the WG (P less than 0.025, P less than 0.05). Transmission electron microscopic observations showed both the secretary particles and metal-granule-like substances (including Zn) of the gland cells in the DG were obviously increased. The lysosomes in the cytoplasm were increased also. The results performed a certain experimental basis for the functional mechanism of the herbal prostatitis decoction treatment.

Animals↗