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Biomedical subjects

M C Kao

Publications and source records attributed to M C Kao.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1991

The biological effects of low power laser irradiation on cultivated rat glial and glioma cells.

Two cell lines were used as models to investigate the biological effects resulting from irradiation by low power lasers. One was a well-established rat glial cell line (RBA-1) obtained from the dissociated culture of normal neonatal rat (JAR-2, F-51) brain tissue. The other was a rat C6 glioma cell line obtained from a propagated culture of rat glial tumor induced by N-nitrosomethylurea. Both of them showed relatively constant cellular morphological characteristics and had steady growth and proliferation in the monolayer system. In this study, the monolayer cell culture was exposed to irradiation by various lasers at low power density in various situations. These lasers with their low energy range are used conventionally in bioregulation and acupuncture, so that their output power primarily will not cause a significant elevation of temperature of the irradiated tissue. The effects on cellular morphology, proliferation, and other functional activities after various conditions of irradiation were studied. A biostimulatory effect was noted after He-Ne laser irradiation on C6 glioma cells and was dose related. A biostimulatory effect was noted also after IR (gallium-arsenide infrared) laser irradiation but was not dose related. No significant biostimulatory effects on RBA-1 cells were noted after exposure to the four types of lasers used in this study.

Animals↗
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↗
PubMed1983

Sedimentation level in chronic subdural hematoma visible on computerized tomography.

A clear interface dividing subdural hematoma into an upper hypodense and a lower hyperdense part was seen on computerized tomography (CT) scan in seven of 140 patients with chronic subdural hematoma. All except one of the seven patients had a definite history of head trauma more than 1 month before they developed acute disturbances of consciousness and pronounced hemiparesis. Consequently, they remained bed-ridden until they underwent drainage of the subdural hematoma. This group was compared to seven chronic subdural hematoma patients with mild clinical manifestations who were selected and intentionally confined to bed for a period before CT examination and craniotomy. The CT scans in this latter group did not show the clear interface in the subdural hematoma seen in the first group. Based on this study, it is hypothesized that this sedimentation level occurred as a result of rebleeding into a chronic hematoma that was sufficiently old to result in its contents being homogenous prior to the rebleed. In cases of rebleeding, a sufficient period of bed confinement in the brow-up position before CT examination allows development of a gravitational sedimentation in the hematoma. This clear level of sedimentation is seen in only a small portion of patients, but this finding may be specific for a significant amount of rebleeding and may herald acute deterioration.

Adult↗