Biomedical subjects

K Fu

Publications and source records attributed to K Fu.

64 records · Page 4Linked to original sources

PubMed1994

[Anesthetic management in a patient with Beckwith-Wiedemann syndrome].

Beckwith-Wiedemann syndrome has three major symptoms, exomphalos, macroglossia and giantism. We report the anesthetic management of a 2-year-old male, weighing 16.1 kg and with a height of 94.6 cm, associated with bilateral retention testis. The anesthesia was maintained with oxygen, nitrous oxide, and sevoflurane. The surgery was completed safely without adverse events such as difficulty in tracheal intubation or refractory hypoglycemia. The anesthetic management of this syndrome requires: an assessment of difficulty in tracheal intubation and treatment, an understanding of the capacity of the patient's glucose metabolism, and assessment of complicated deformities. In particular, it is necessary to carry out a preoperative examination of the cardiovascular system.

Anesthesia, Inhalation↗

PubMed1993

Delayed implantation of demineralized bone powder after local irradiation in rats.

Previous studies have shown that osteoinduction is inhibited when demineralized bone powder (DBP) is implanted within 48 hours of local irradiation (i.e., when the acute effects of radiation injury are present). This study sought to determine whether normal osteoinduction can proceed if the implantation of DBP is delayed until 21 days postirradiation. At 21 days, the acute effects of radiation injury are likely to have subsided, but the long-term effects have not yet appeared. Twenty-eight-day-old rats were administered a radiation dose of either 7 or 20 Gy over a localized area of one thigh. The contralateral, nonirradiated thigh served as a control. Demineralized bone powder was subcutaneously implanted 21 days later. Subcutaneous pellets were retrieved at various intervals thereafter (up to Day 45) and were histologically graded for evidence of osteoinduction. No difference in osteoinduction was detected at any time interval in pellets from the 7-Gy-treated sites, compared with controls. Pellets from the 20-Gy-treated sites, however, demonstrated significantly a lower osteoinductive response at each interval. These latter pellets showed small scattered areas of osteoinduction and reduced formation of marrow elements. Thus, although osteoinduction proceeds normally when the implantation of DBP is delayed for 21 days after irradiation with 7 Gy, this is not the case when 20 Gy are administered. Given the absence of gross impairment of tissue vascularity in irradiated sites, it is possible that inhibition of osteoinduction after higher doses of radiation results from permanent damage to mesenchymal precursor cells.

Animals↗

PubMed1992

Evidence for variable rates of recombination in the MHV genome.

Mouse hepatitis virus has been shown to undergo RNA recombination at high frequency during mixed infection. Temperature-sensitive mutants were isolated using 5-fluorouracil and 5-azacytidine as mutagen. Six RNA+ mutants that reside within a single complementation group mapping within the S glycoprotein gene of MHV-A59 were isolated which did not cause syncytium at the restrictive temperature. Using standard genetic techniques, a recombination map was established that indicated that these mutants mapped into two distinct domains designated F1 and F2. These genetic domains may correspond to mutations mapping within the S1 and S2 glycoproteins, respectively, and suggest that both the S1 and S2 domains are important in eliciting the fusogenic activity of the S glycoprotein gene. In addition, assuming that most distal ts alleles map roughly 4.0 kb apart, a recombination frequency of 1% per 575-676 bp was predicted through the S glycoprotein gene. Interestingly, this represents a threefold increase in the recombination frequency as compared to rates predicted through the polymerase region. The increase in the recombination rate was probably not due to recombination events resulting in large deletions or insertions (greater than 50 bp), but rather was probably due to a combination of homologous and nonhomologous recombination. A variety of explanations could account for the increased rates of recombination in the S gene.

Chromosome Mapping↗

PubMed1992

Recurrent locally advanced nasopharyngeal carcinoma treated with heavy charged particle irradiation.

Between June 1981 and May 1990, 11 patients with recurrent locally advanced nasopharyngeal carcinoma were treated with heavy charged particle radiation at Lawrence Berkeley Laboratory. All patients had previously undergone full course radiotherapy to a median dose of 70.2 Gy [range 61-81 Gy]. Median time to recurrence was 18.2 months. At the time of heavy charged particle radiotherapy treatment, all had evidence of invasion of the base of skull and 7 of 11 had cranial nerve deficits. None of the patients were candidates for brachytherapy because of tumor extent or poor geometry. The tumor histology was squamous cell carcinoma in 10 patients and lymphoepithelioma in one patient. Ten of the 11 patients had received chemotherapy prior to re-irradiation. The heavy charged particle tumor dose delivered ranged from 31.80 GyE to 62.30 GyE (average 50.25 GyE, median 50 GyE). Local control was achieved in 45%. Median survival was 42 months. Actuarial survival was 59% at 3 years and 31% at 5 years (Kaplan-Meier). There were no fatal complications. The results in treating locally advanced recurrent nasopharyngeal carcinoma with heavy charged particles appear superior to those reported by others using photon therapy.

Carcinoma, Squamous Cell↗

PubMed1990

Genetics of mouse hepatitis virus transcription: identification of cistrons which may function in positive and negative strand RNA synthesis.

A panel of 26 temperature-sensitive mutants of MHV-A59 were selected by mutagenesis with either 5-fluorouracil or 5-azacytidine. Complementation analysis revealed the presence of one RNA+ and five RNA- complementation groups. None of the RNA- complementation groups transcribed detectable levels of positive- or negative-stranded RNA at the restrictive temperature. Temperature shift experiments after the onset of mRNA synthesis revealed at least two classes of RNA- mutants. RNA- complementation groups A, B, D, and E were blocked in the ability to release infectious virus and transcribe mRNA and genome, while group C mutants continued to release infectious virus and transcribe both mRNA and genome. Temperature shift experiments at different times postinfection suggest that the group C mutants encode a function required early in viral transcription which affects the overall rate of positive strand synthesis. Analysis of steady state levels of negative strand RNA after the shift indicate that the group C mutants were probably blocked in the ability to synthesize additional minus strand RNA under conditions in which the group E mutants continued low levels of minus strand synthesis. These data suggest that at least four cistrons may be required for positive strand synthesis while the group C cistron functions during minus strand synthesis.

Animals↗

PubMed1990

Establishing a genetic recombination map for murine coronavirus strain A59 complementation groups.

MHV-A59 temperature-sensitive mutants, representing one RNA+ and five RNA- complementation groups, were isolated and characterized by genetic recombination techniques. Maximum recombination frequencies occurred under multiplicities of infection greater than 10 each in which 99.99% of the cells were co-infected. Recombination frequencies between different ts mutants increased steadily during infection and peaked late in the virus growth cycle. These data suggest that recombination is a late event in the virus replication cycle. Recombination frequencies were also found to range from 63 to 20,000 times higher than the sum of the spontaneous reversion frequencies of each ts mutant used in the cross. Utilizing standard genetic recombination techniques, the five RNA- complementation groups of MHV-A59 were arranged into an additive, linear, genetic map located at the 5' end of the genome in the 23-kb polymerase region. These data indicate that at least five distinct functions are encoded in the MHV polymerase region which function in virus transcription. Moreover, using well-characterized ts mutants the recombination frequency for the entire 32-kb MHV genome was found to approach 25% or more. This is the highest recombination frequency described for a nonsegmented, linear, plus-polarity RNA virus.

Animals↗

PubMed1989