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Biomedical subjects

M C Kao

Publications and source records attributed to M C Kao.

At least 19 recordsLinked to original sources
PubMed1992

Multidrug resistant HOB1 lymphoma cells express P-glycoprotein that does not play the major role in the development of drug resistance to adriamycin.

Two cell lines resistant to 0.1 microM vincristine (VCR) and 2.0 microM adriamycin (ADR), respectively, (designated HOB1/VCR0.1 and HOB1/ADR2.0) were established from a human immunoblastic B lymphoma cell line. These cell lines showed the typical MDR phenotype with overexpression of P-glycoprotein and decreased [3H]VCR accumulation. The retention amounts of intracellular [3H]VCR in these two cell lines could be augmented by verapamil. However, in spite of the overproduction of P-glycoprotein, both HOB1/VCR1.0 and HOB1/ADR2.0 cells did not exhibit decreased accumulation of intracellular [14C]ADR. And the retention of [14C]ADR was not affected by verapamil. Our data support that P-glycoprotein is a drug transporter more important for the development of drug resistance to VCR than to ADR.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

Laser endoscopic sympathectomy for palmar hyperhidrosis.

Hyperhidrosis palmaris is a common disorder among the Orientals. Despite numerous therapeutic modalities in practice, none has proved entirely satisfactory. With the introduction of video-endoscopic surgery, we combined this system with a fiber optic Nd-YAG laser unit, electrocautery, and a laser Doppler flowmeter to design a new and promising therapeutic technique for palmar hyperhidrosis. General anesthesia with alternating one-lung ventilation is essential for a safe and smooth endoscopic sympathectomy. An operating endoscope was introduced into thoracic cavity via the second intercostal space and then attached to a CCD camera video system, which provided clear visibility of the sympathetic trunk in most cases. The proper level of the sympathetic trunk was further confirmed with the aid of vasomotor response of the palmar skin resulting from electric stimulation on the related sympathetic trunk. Finally, the confirmed target was precisely vaporized with a low power Nd-YAG laser through an endoscope. Twenty patients underwent bilateral sympathectomy, mostly on T2 and its adjacent trunk. This technique did not cause any injury to the lung or bleeding. No Horner's syndrome was produced. It provided a precise ganglionectomy on a confirmed target under clear magnified vision. Consequently, a definite and long-lasting therapeutic effect seemed warranted. It was considered to be a relative minor and safe procedure causing minimal discomfort and an almost invisible scar without producing serious complications. It also shortened the operation time and hospital stay remarkably in comparison with other open sympathectomy procedures.

Adolescent↗
PubMed1992

Video endoscopic sympathectomy using a fiberoptic CO2 laser to treat palmar hyperhidrosis.

Palmar hyperhidrosis is a common disorder among orientals. A new therapeutic technique for this disorder has been designed by combining a computer compact disc video endoscopic system with a fiberoptic CO2 surgical laser unit. The operation is performed under general anesthesia with alternating one-lung ventilation. There are three important aids in localizing the correct sympathetic segment: 1) direct visualization of its magnified image on the television monitor; 2) identification with an electrode probe palpation at its presumed location; and 3) monitoring the microvasomotor changes on the skin of the finger resulting from electrical stimulation of the sympathetic trunk. Subsequently, the confirmed sympathetic target is vaporized using a low power CO2 laser under direct vision on the television monitor. The laser is delivered to the target by a small optical fiber passing through a throacoscope, which is introduced into the thoracic cavity via the intercostal space between the second and third ribs at the midclavicular line. Fourteen palmar hyperhidrosis patients were successfully treated by this method. No complications, such as Horner's syndrome, bleeding, or intercostal neuralgia, were encountered. Although the number of cases treated was small, and the follow-up period was short, the evidence indicates that a definite sympathectomy on a confirmed segment under magnified vision is possible with this procedure, and could warrant a definite and long-lasting therapeutic effect. Based on our experience, the method is considered a relatively minor and safe procedure, causing minimal discomfort and almost invisible scars. The operation time and hospital stay were remarkably shortened in comparison with other conventional sympathectomy procedures.

Adolescent↗
PubMed1992

The effect of lasers on glycocalyx production by staphylococcus.

The present study was undertaken to evaluate the effects of lasers on glycocalyx production by Staphylococcus epidermidis. Three strains of S. epidermidis were irradiated (He-Ne, Ga-As, CO2, and argon laser) at different energy densities ranging from 0.24 to 100 J/cm2. The viability of the bacteria was measured by colony forming units (CFU) and glycocalyx production was quantitated by toluidine blue staining and spectrophotometer. The He-Ne, Ga-As, and Co2 laser (2W; 90 J/cm2) had no effect on glycocalyx production and CFU, when compared to the control group (p greater than 0.05). However, glycocalyx production by the high-producer strains of S. epidermidis was significantly suppressed by agron laser when compared to the control group (p less than 0.05). It was concluded that the agron laser is a potentially advantageous mean of inhibiting the glycocalyx production by S. epidermidis.

Glycoproteins↗
PubMed1992

Conization with a carbon dioxide laser as a uterine-preservation operation for patients with preinvasive cervical carcinoma.

Preinvasive cervical carcinoma (PCC) is a disease entity of the uterine cervix resulting from carcinoma in situ and various degrees of dysplasia. These cases are conventionally treated by a total abdominal hysterectomy. Effective management that can preserve the uterus is more desirable than hysterectomy. In this report, we present the results and complications of laser conization as a uterine-preservation treatment. At our dysplasia clinic, cases of reproductive age diagnosed with PCC can voluntarily undergo laser conization. From June 1985 to May 1988, there were 26 cases who received this treatment. After treatment, they were regularly followed up for more than three years. Before and after surgery, these cases were evaluated by a Pap smear for cytology, colposcopy, a cervical punch biopsy and endocervical curettage for histopathology. Eighteen cases with a satisfactory colposcopy were treated by laser vaporizing conization. Eight cases with an unsatisfactory colposcopy were treated by laser excisional conization. Their mean age was 35.8 (SD 7.7) years, and parity was 1.5 (SD 0.9). The instrument used was a Sharplan CO2 laser model 720. The power density was around 1,000 W/cm2 for vaporization, and 1,500 W/cm2 for excisional conization. During the operations, there was little bleeding. No case required a blood transfusion. The vaginal discharge decreased within four days after treatment. The cervical epithelium on the operated wound began growing after the second week, and the cervix healed well in four to six weeks. After healing, the squamocolumnar junction in each case was visible on colposcopy. No case suffered from cervical stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

NMDA antagonists attenuate hypertension induced by carotid clamping in the rostral ventrolateral medulla of rats.

The purpose of these experiments were to study the interactions of N-methyl-D-aspartate (NMDA) with baroreceptor reflexes induced by transient carotid clamping. Adult male Sprague-Dawley rats were anesthetized with urethane. Bilateral common carotid artery occlusion resulted in a reversible and reproducible hypertension in the vagotomized animals. This hypertensive reaction was blocked by intraventricular injection of NMDA antagonists, such as 2-amino-7-phosphono-heptaneoate (AP-7) and phencyclidine (PCP). We also found that blood pressure-sensitive neurons of the rostral ventrolateral medulla (RVLM) could be classified into two groups, on the basis of their responses to norepinephrine given intravenously. Using pressure microejection and single unit recording, we observed that clamping of the common carotids resulted in excitation of type I neurons. This evoked excitation, similar to that induced by NMDA, was blocked by locally applied AP-7. However, the carotid occlusion-induced responses of type II neurons were not blocked by AP-7. In conclusion, the present data suggest that NMDA receptors are involved in hypertensive responses during carotid occlusion, perhaps involving a site in the rostral ventrolateral medulla.

2-Amino-5-phosphonovalerate↗
PubMed1990

Facilitation of GABA-induced depression with PCP and sigma receptor agonists was mediated through catecholaminergic pathways.

The purpose of this experiment was to investigate the interactions of norepinephrine with PCP (phencyclidine) and sigma receptor agonists--modulated GABA (gamma aminobutyric acid) response in the cerebellum. Drugs were directly applied to a single cerebellar Purkinje neuron of urethane-anesthesitized rat through a multibarrel pipette. (+)PCMP [1-(-1-phenylcyclohexyl)-3-methyl piperidine], a PCP receptor agonist, and dexoxadrol, a sigma receptor agonist, significantly enhanced GABA induced inhibition. In norepinephrine-depleted animals, however, both (+)PCMP and dexoxadrol did not modulate GABA's effect. In conclusion, our findings indicated that the PCP/sigma-induced facilitation of GABA reactions were mediated through noradrenergic system in the cerebellum.

Animals↗
PubMed1990

Comparison of 5' region sequences of human and rabbit phosphofructokinase genes.

A phosphofructokinase gene was screened and cloned from a human genomic library prepared in the lambda EMBL4 phage vector. DNA sequencing shows that the first exon of this human phosphofructokinase gene is identical in length and highly homologous in sequence to that of a rabbit phosphofructokinase gene. Two amino acid replacements are indicated, an Arg----Lys and a Val----Ile at positions 9 and 13, respectively. Eleven base substitutions, 8 of them silent, are identified. Surprisingly, at ten of these sites, complete bias for A's and T's in the human gene and C's and G's in the rabbit gene are seen. Strong conservation is also observed in the 5' untranslated region and for the first 15 base pairs in the intron. All the nine variant nucleotides in these regions are, again, A's and T's in the human gene and G's and C's in the rabbit gene. The unit evolutionary period of change between the first exon of rabbit and human phosphofructokinase genes is estimated as 2.3 million years at silent sites and 15.6 million years at replacement sites.

Amino Acid Sequence↗
PubMed1990

The rabbit muscle phosphofructokinase gene: cDNA cloning and sequencing.

A partial cDNA for rabbit muscle phosphofructokinase (Rm-PFK) has been cloned and sequenced. The nucleotide sequence of the cDNA agrees with the previously determined Rm-PFK genomic sequence. In addition, the amino acid sequence deduced from the cDNA is nearly identical to the Rm-PFK sequence previously determined by peptide analysis. A significant degree of homology exists when the amino acid sequence of Rm-PFK is compared with the sequences of Bacillus stearothermophilus PFK or Escherichia coli PFK-1. The cloning and sequencing of the PFK cDNA fragment represents significant progress toward the long term goal of using site-specific mutagenesis to investigate the structure-function relationships in this allosteric enzyme.

Amino Acid Sequence↗
PubMed1987

The rabbit muscle phosphofructokinase gene. Implications for protein structure, function, and tissue specificity.

Sequence homologies between bacterial and rabbit muscle phosphofructokinases and between the amino- and carboxyl-terminal halves of the latter suggest that the mammalian enzyme evolved from a prokaryotic progenitor by gene duplication and divergence (Poorman, R. A., Randolph, A., Kemp, R. G., and Heinrikson, R. L. (1984) Nature 309, 467-469). We have isolated the gene for the rabbit enzyme and determined the nucleotide sequence for all the exons and most of the introns. This represents the first eukaryotic phosphofructokinase gene ever sequenced. The cloned gene is 17 kilobase pairs long. The coding sequence for 780 amino acids is split into 22 exons ranging in size from 15 to 63 codons. Sequence analysis shows that 75% of the bases at the third position of the codons in these exons are either G or C. Exons XV and XVI code for the 30 amino acid residues which were left unidentified in the published primary structure for this enzyme. When overlaid on the structure of the protein, most of the introns are located between or near the ends of the secondary structural elements but not at analogous positions in the two protein-coding halves of the gene.

Amino Acid Sequence↗