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Biomedical subjects

M H Cheng

Publications and source records attributed to M H Cheng.

At least 37 records · Page 2Linked to original sources
PubMed1998

In vitro evaluation of the cytotoxicity and genotoxicity of root canal medicines on human pulp fibroblasts.

An intracanal medicine is often required because microorganisms in the dentinal tubes may be difficult to eliminate completely by instrumentation. Phenolic compounds are widely used in dental treatment as sedatives for the dental pulp or as disinfectants for caries and the root canal. In this study, propidium iodide fluorescence and DNA precipitation assay were used to investigated the cytotoxic and genotoxic effects of camphorated phenol and camphorated parachlorophenol on cultured human pulp fibroblasts in vitro. Both medicines reduced the content of double-stranded polynucleic acid of fibroblasts over a 24-h culture period in a concentration-dependent manner. Camphorated parachlorophenol was more cytotoxic than camphorated phenol. But, both medicines did not cause genotoxicity on pulp cells. The advantage of these experimental methods are simplicity and rapidity. Furthermore, this experimental system may be useful for preliminary cytotoxicity and genotoxicity screening of various dental medicines in vitro.

Anti-Infective Agents, Local↗
PubMed1998

Posterior interosseous flap and its variations for coverage of hand wounds.

BACKGROUND: Conventional posterior interosseous flap has the disadvantage of partial or even complete necrosis of the flap when there is anatomical variation or contusion around its distal pedicle. To make it a more reliable flap, three types of auxiliary procedures were designed. METHODS: (1) When there is congestion after inset of the distally based flap, an additional venous anastomosis was carried out. (2) When there is anatomical variation so that a distally based flap could not be raised without compromising the nerve branches, or when contusion was found around the distal pedicle, the flap was changed into a free flap. This design is also indicated for coverage of the distal fingers. (3) When the patient is elderly with possible peripheral arterial disease, the flap was raised with a wide base, incorporating the branches of both the anterior and posterior interosseous arteries. There were eight, 36, and five patients in each group, respectively. RESULTS: There was only one failure in the free flap group. No partial necrosis of the flap was found. Other complications were analyzed. CONCLUSION: With these backup procedures, the posterior interosseous flap can be more widely used with safety. By combining various reconstructive armaments, the result of a conventional procedure can be improved.

Adolescent↗
PubMed1998

Single versus double arterial anastomoses in combined second- and third-toe transplantation.

Combined second and third toe transplantation is one good option for reconstruction of multiple digit amputation. However, the use of one or two arteries for pedicle anastomoses, which may influence the vascular complication and success rate, has never been addressed in the literature. This study includes a retrospective review of 57 combined second and third toe transplantation in 54 patients performed from February of 1983 through December of 1996. Group I, composed of 41 transplantations, underwent one arterial anastomosis, and group II, composed of 16 transplantations, underwent double arterial anastomoses during surgery if there were two recipient arteries available or whenever the second and third toes showed inadequate blood perfusion after one arterial anastomosis. In group I, 10 transplantations (24.4 percent) required re-exploration with a success rate of 92.7 percent (38 out of 41 transplantations). In group II, only one transplantation (6.2 percent) required re-exploration with successful flap salvage. The success rate was 100 percent for group II. Because the re-exploration and success rates between groups I and II were not statistically significant according to two-tailed Fisher's exact test, the combined second and third toe transplantation is a reliable procedure using either single or double arterial anastomoses.

Adolescent↗
PubMed1998

Cytotoxic and non-genotoxic effects of arecoline on human buccal fibroblasts in vitro.

Betel quid chewing has been linked to oral submucous fibrosis and oral cancer. Cytotoxicity and genotoxicity assays were used to investigate the pathobiological effects of arecoline on cultured human buccal fibroblasts. Arecoline increased double-stranded polynucleic acid at the concentration of 0.1 to 10 micrograms/ml in a concentration-dependent manner. At a concentration higher than 50 micrograms/ml, arecoline was cytotoxic to cultured fibroblasts and the cytotoxicity was dose-dependent. No genotoxicity for arecoline was found even at a concentration of 400 micrograms/ml. On the other hand, 600 micrograms/ml glutathione (GSH) and 200 micrograms/ml glycyrrhizin could prevent the arecoline-induced cytotoxicity. These results indicate that arecoline is a cytotoxic agent and no genotoxicity was found to human buccal fibroblasts. Furthermore, increasing consumption of GSH- and glycyrrhizin-rich foods may reduce the oral diseases associated with betel quid chewing.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1997

Localization of protein kinase C alpha and zeta during the decidualization in pseudopregnant rats.

Our previous data showed that at least five PKC isoforms (alpha, delta, zeta, lambda and tau) were present in the decidualization. In this study, we then localized the PKC alpha and zeta by immunohistochemistry in the decidualized uterine tissues. The decidualized uterine tissues were induced by trauma-stimulation and fixed in formalin. The immunofluorescence were photographed by confocal microscope. The data revealed that the fluorescence of PKC alpha was present in the deciduomata and myometrium. In the deciduomata, PKC alpha was mainly located in the surrounding nuclear. This phenomenon of localization was especially performed on day 2 and 3 of the decidualization, just on the time of higher frequence of cell mitosis. Since the myometrium with hypertrophy did not display the phenomenon of perinuclear localization, these suggested that the expression and localization of PKC alpha may be associated with the cell proliferation. On the other hand, the PKC zeta was also present and distributed broadly in the deciduomata and myometrium. This expression was increased and similar to the previous Western blot studies. Thus, the data confirmed that the various expression and localization of PKC isoforms may be correlated with the development of deciduomata.

Animals↗
PubMed1997

Malignant fibrous histiocytoma degeneration in a patient with facial fibrous dysplasia.

Seventy-two patients with craniofacial fibrous dysplasia were treated during a period of 18 years. Only 1 patient (1.4%) developed malignant degeneration into malignant fibrous histiocytoma. Total excision including the gross mass and adjacent facial bone was performed at that time, however the patient refused an orbital exenteration and postoperative adjuvant therapy. Tumor recurrence developed 2 years later and the patient died. To our knowledge this is the first report describing malignant fibrous histiocytoma degeneration from a fibrous dysplasia localized to the facial bones. Although complete curative treatment could not be undertaken in this case, some conclusions can be drawn regarding the clinical course of this uncommon entity.

Adult↗
PubMed1997

Intracranial meningioma with intratumoral hemorrhage.

Meningiomas associated with intracranial hemorrhage are rare. Clinical presentation is frequently sudden. We present two patients with intracranial meningioma and intratumoral hemorrhage. One patient suffered concomitant intracerebral hemorrhage, which resulted in a decreased level of consciousness and hemiparesis. There was no evidence of coagulopathy in either patient. The patients underwent surgery for evacuation of the hematoma and tumor excision resulting in good recovery of neurologic function. The pathology reports revealed meningiomas; one was a syncytial type and the other was angioblastic. We reviewed 22 cases of meningioma associated with intratumoral hemorrhage, including our own, and found that death occurred in 55% (12/22) of patients with hemorrhagic complications. In the computed tomography (CT) era, there were 13 patients; of these, seven (58%) had recovered, and five (38%) died. There were nine cases from the pre-CT era; of these, seven (78%) died, and none had a good recovery. Early diagnosis with definitive surgery can bring about a more favorable outcome.

Adult↗
PubMed1997

Preoperative ultrasound Doppler study and clinical correlation of free posterior interosseous flap.

BACKGROUND: Conventional pedicled posterior interosseous flap has a relatively high rate of partial flap loss which may result in ultimate failure to provide coverage of this important structure. The goal of this study was to delineate the posterior interosseous flap as a reliable free tissue transfer. METHODS: From 1991 to 1995, 34 patients undergoing free posterior interosseous flap had preoperative Doppler mapping to determine the point of emergence of the skin perforators of the posterior interosseous artery. This finding was correlated intraoperatively with the number of perforators nourishing the posterior interosseous flap. The anatomic variations in the posterior interosseous artery were also identified. RESULTS: These results showed (1) the main skin perforator was consistent and reliable in all of the posterior interosseous flaps both in the preoperative Doppler evaluation and intraoperative findings; (2) the main skin perforator arose from the posterior interosseous artery, the ascending interosseous recurrent artery or the common interosseous artery in 26 cases (76%), 6 cases (17.6%) or 2 cases (5.9%) respectively; (3) the success rate with the use of the free posterior interosseous flap was 97% without any partial flap loss. CONCLUSION: It is concluded that the free posterior interosseous flap is a reliable flap with adequate arterial flow from constant main skin perforators and large antegrade venous drainage. A less reliable distally based pedicle flap can be changed into a reliable free flap, with the aid of preoperative non-invasive Doppler evaluation. This principle could be applied in the design of other "free skin perforator flaps".

Arteries↗
PubMed1996

Ganglion cyst in the ligamentum flavum of the cervicothoracic junction.

A case of thoracic myelopathy secondary to a ganglion cyst originating from the ligamentum flavum at the C7 T1 level is reported. Magnetic resonance imaging (MRI) demonstrated an extradural oval mass at the C7/T1 level with thecal sac and cord compression. Surgical decompression and excision of the ganglion cyst resulted in a good neurologic recovery. Intraspinal ganglion cysts are rare entities. We review the literature and discuss the pathologic findings, pathogenesis and radiologic presentation of ganglion cysts.

Female↗
PubMed1996

Intraspinal extradural arachnoid cyst with spinal cord herniation.

A 17-year-old male presented with thoracic myelopathy 12 months after a stab injury to the thoracic spine. The patient reported that symptoms and signs had gradually worsened in the 3 months prior to his examination. Magnetic resonance imaging depicted not only an extradural arachnoid cyst but severe spinal cord compression. The cerebrospinal fluid pressure and dynamics associated with herniation of the spinal cord resulted in the formation and enlargement of an extradural arachnoid cyst. The pressure effect of the cyst accounted for the thoracic myelopathy.

Adolescent↗
PubMed1995

Recordings of pre- and postoperative sympathetic skin response in patients with palmar hyperhidrosis.

Transthoracic endoscopic sympathectomy is an accepted standard surgical treatment for hyperhidrosis palmaris. During the past 4 years, more than 500 patients underwent this kind of surgical treatment at our institution with a 98% success rate. About 50% of cases were found to have compensatory sweating. We measured the sympathetic skin response (SSR) and R-R interval variation (RRIV) in 38 normal control subjects, and 50 consecutive patients with palmar hyperhidrosis before and 2 weeks after transthoracic endoscopic T2-3 sympathectomy. Before sympathectomy SSR was absent in 36% of patients on deep inspiratory stimulation and in 20% on electrical stimulation. After T2-3 sympathectomy, SSR in the palms was absent in 64% of patients with deep inspiration stimulation and in 76% on electrical stimulation. A decrease in the SSR amplitude in the soles was found in 40% on deep inspiration and in 54% of patients on electrical stimulation. RRIV was not significantly influenced 2 weeks after sympathectomy. The high abnormal rate of SSR in the patient group indicated that an abnormal regulation of the sudomotor control center played an important role in palmar hyperhidrosis.

Adolescent↗
PubMed1994

Unstable fracture of thoracolumbar spine treated with pedicle screw plating. A report of 90 cases.

Ninety cases of unstable fracture of thoracolumbar spine treated with a modified Roy-Camille type of pedicle screw plating are reported. They were followed up for an average of 2 years and 5 months. Comparing the pre- and postoperative X-ray films for the angles of kyphosis, degrees of compression of anterior vertebral height and degrees of displacement, the results were quite satisfactory. A complete reduction was obtained in 74% of the unstable fractures at the levels between the T11 and L3 vertebrae. This kind of internal fixation has been proved to be strong and safe allowing for early mobilization with few complications. The operative technique is described and the causes of complication are analyzed.

Adolescent↗
PubMed1991

Cold inhibits neurite outgrowth from single retinal ganglion cells isolated from adult goldfish.

We have studied the growth of neurites from single retinal ganglion cells isolated from adult goldfish and maintained under various primary cell culture conditions. In 10% Leibovitz's L-15 medium at 23 degrees C, these ganglion cells remained viable for up to 10 days and generated extensive fields of neurites. We found two patterns of neuritic fields. In one, a pair of neurites exited from opposite sides of the cell soma, forming a bipolar pattern. In the second pattern, three to five neurites exited from several points around the soma, forming a multipolar pattern. Characteristically, each neurite of this latter type tapered and branched two to seven times, whereas neurites forming bipolar patterns showed less branching and little or no taper. The fields subtended by the neurites in multipolar patterns ranged in size from 33,000 to 204,000 microns 2. Finally, although these neurites grew as fast as 35 microns hr-1 at 23 degrees C and individually reached lengths of up to 735 microns, they showed essentially no growth at 13 degrees C. Neurite outgrowth at 23 degrees C was vigorous even in cells whose growth had previously been suppressed for as long as 8 hr at 13 degrees C.

Animals↗
PubMed1991

Synchronous neurite branchings in single goldfish retinal ganglion cells.

We have examined the time course of branch formation in neurites of retinal ganglion cells isolated from adult goldfish (Carassius auratus). These neurites elongate at approximately 13 microns/h, and usually branch by bifurcation of growth cones at their tips. The times elapsed between branchings in different neurites of single cells can be described by a Poisson distribution with a mean interval of approximately 2 h. As predicted by this distribution, a relatively large number of branchings occur simultaneously in different neurites of individual cells. Simultaneous branchings of neurites elongating at a common rate generate branch points that lay equidistant from their soma. Since similar branching patterns can be seen in dendrites of retinal ganglion and amacrine cells in situ, these results are consistent with the possibility that dendrites of individual neurons branch synchronously and grow at common rates during development.

Animals↗
PubMed1990

Capillary plasma ammonia concentration in neonates receiving total parenteral nutrition. Comparison with arterial and venous concentrations.

Plasma ammonia concentration in neonates has routinely been determined using arterial or venous blood. Expected plasma ammonia values in capillary blood obtained by heelstick have not been determined. We compared ammonia levels in 20 sets of plasma from simultaneously drawn arterial, venous, and capillary blood in a group of neonates receiving total parenteral nutrition. Mean ammonia concentrations in venous (107 +/- 44) and capillary blood (112 +/- 33) were 45% and 51% higher, respectively, than corresponding arterial (74 +/- 22) values (P less than .001). Ammonia levels in blood obtained by venipuncture (Ven), however, did not correlate consistently with arterial (Art) values (r = .43; Art = 51 + 0.21 Ven; P greater than .05). In contrast, ammonia levels in capillary blood (Cap) correlated well with arterial values (r = .86; Art = 10.3 + 0.6Cap; P less than .001). Ammonia levels in neonates may be reliably interpreted using the latter regression equation when blood for analysis is obtained by a properly performed heelstick, allowing the preservation of arteries and veins, and sparing the infant from repetitive needle punctures. Ammonia levels in blood obtained by venipuncture do not adequately correlate with arterial values and therefore may be therapeutically misleading.

Ammonia↗
PubMed1990

Stability of captopril in powder papers under three storage conditions.

The stability of captopril in powder papers under three different storage conditions was determined. Captopril 12.5-mg tablets were triturated with lactose to a final concentration of 2 mg of captopril in 100 mg of powder. A total of 240 powder papers were prepared and stored in class "A" prescription vials (80 papers), 002G plastic zip-lock bags (80 papers), and Moisture Proof Barrier Bags (80 papers). Immediately after preparation and at 1, 2, 3, 4, 8, 12, and 24 weeks of storage at room temperature, powder papers under each storage condition were reweighed and the contents were assayed for captopril concentration by a stability-indicating high-performance liquid chromatographic method. More than 90% of the initial captopril concentration was retained under all storage conditions during the first 12 weeks of the study. Captopril disulfide, a degradation product, was detected in one sample stored in a plastic zip-lock bag at 24 weeks. Captopril was stable for the entire 24-week period in powder papers stored in either the class A prescription vial or the Moisture Proof Barrier Bag. Captopril in powder papers is stable for at least 12 weeks when stored at room temperature under all three storage conditions.

Captopril↗