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Biomedical subjects

K M Chan

Publications and source records attributed to K M Chan.

At least 199 records · Page 11Linked to original sources
PubMed1993

The Johnson antishear device and standard shin pad in the isokinetic assessment of the knee.

Isokinetic training and assessment of the knee joint has been the mainstay of rehabilitation, especially in patients with anterior cruciate ligament deficiency. Besides the original shin pad used, the antishear device was introduced by Johnson in 1982. This device has been shown biomechanically to prevent excessive anterior translation of force on the tibia during training. However, there is a need to compare the antishear device and the standard shin pad in the isokinetic assessment. Hence, the major objective of this study is to define, if any, the difference in patient assessment between the new double pad device and the old single shin pad. Ten subjects with no previous history of injury on either knee were tested with the Cybex Isokinetic Dynamometer. There were four men and six women and the mean age was 25.2 years. They were randomized into different test sequences with different shin pads at different speeds. Correlation and paired t tests (P) were performed to find out the correlation and difference between the two devices. There was significant difference in performance assessment between the two devices in knee extension (P < 0.05) but no significant difference in knee flexion (P > 0.05). There was also a high correlation (r > 0.75) between the two devices. It is concluded that because of the significant difference of data generated between the two devices, it is important to select one single device with each patient during a series of testings.

Adult↗
PubMed1993

Sports causing most injuries in Hong Kong.

A prospective survey was carried out on 2293 patients attending the Sports Injury Clinic in the Prince of Wales Hospital between May 1984 and December 1990. A Sports Injury Report Form was completed for each patient. Subjects in this study represent a group of nonprofessional and non-élite athletes in a metropolitan area. Soccer, basketball, volleyball, long-distance running and cycling in descending order were the five most common sports causing injury. Different sports produced different injury patterns. In four of the five sports, the knee (27.27-50.47%) and the ankle (16.78-24.67%) were the commonest sites of injury. In cycling, the face (19.46%) was the commonest site of injury. There was a higher injury rate to the lower than the upper limb in soccer, basketball, volleyball and long-distance running, with a ratio of upper- to lower-limb injury ranging from 1:1.13 to 1:46.10. In cycling, upper limb injury was more frequent (upper- to lower-limb injury ratio was 1:0.53). Sprain was the commonest injury overall (44.60%). It was also the commonest injury condition in volleyball (55.15%), basketball (55.34%), soccer (51.41%) and long-distance running (39.33%). In cycling, abrasion (24.83%) was commonest.

Adolescent↗
PubMed1993

A patient with recurrent hypothermia associated with thrombocytopenia.

A 69 year old woman had 13 hospital admissions because of hypothermia attributed to self-neglect. On each occasion she was found to be thrombocytopenic, and the platelet count always returned to normal with rewarming. The case records of all patients admitted to the Victoria Infirmary between 1986 and 1990 with a primary diagnosis of hypothermia were reviewed. Two other patients of the 75 assessed were found to have had thrombocytopenia linked to hypothermia, but neither showed a recurrent relationship.

Aged↗
PubMed1993

Tissue kallikrein and tonin levels in submandibular glands of STZ-induced diabetic rats and the effects of insulin.

The levels of tissue kallikrein, tonin, and other kallikrein-like proteinases were determined in extracts of rat submandibular glands 3 mo after the induction of diabetes with STZ (65 mg/kg i.v.). Total kallikrein-like proteinase activity was assayed catalytically with the fluorogenic substrate DVLR-AFC. Tissue kallikrein was assayed by using the same substrate in the presence of SBTI. Activity of other kallikrein-like proteinases was defined as the difference between the total kallikrein-like activity and that of tissue kallikrein. Tonin was assayed by using the substrate ZVKKR-AFC in the presence of aprotinin. Results were compared with age-matched controls and with diabetic rats that had received daily insulin injections for the last week of the test period. The results showed that all activities were significantly reduced in diabetic glands compared with controls. Insulin treatment restored concentrations of tissue kallikrein activity, whereas the activities of tonin and other kallikrein-like proteinases were unchanged. RIA supported these findings. The results indicate that in rat submandibular glands, insulin affects the synthesis of kallikrein-like proteinases in different ways and, allowing for the slowness of the processes involved, insulin may exert a direct influence on the regulation of tissue kallikrein synthesis but only have indirect effects on the synthesis of tonin and the closely related kallikrein-like proteinases.

Amino Acid Sequence↗
PubMed1993

Severe isopropanolemia without acetonemia or clinical manifestations of isopropanol intoxication.

This is the first reported case of severe isopropanolemia in a patient who did not experience associated clinical manifestations and acetonemia. The patient was found lying face down in a hotel lobby but at admission was alert and oriented to place and person. Toxicological analysis of the patient's serum revealed the presence of isopropanol at a concentration of 72 mmol/L. An increased serum osmolal gap (81 mOsm/kg) was also observed. The serum concentration of isopropanol decreased to 9.5 mmol/L 15.5 h after admission with an estimated half-life of elimination of 5-7 h. No serum acetone was detected throughout the patient's hospitalization. The identity of isopropanol was confirmed by gas chromatography/mass spectrometry. The patient remained awake and alert while in the hospital and was discharged 5 days after admission. These unusual findings raise some fundamental questions about the role of isopropanol conversion to acetone in the manifestation of symptoms usually associated with isopropanol intoxication.

1-Propanol↗
PubMed1992

P-glycoprotein genes in the winter flounder, Pleuronectes americanus: isolation of two types of genomic clones carrying 3' terminal exons.

In mammals, P-glycoprotein (P-gp) is encoded by two or more highly conserved genes that differ in their abilities to transport drugs. One isoform class (class I) is consistently associated with the multidrug resistance phenotype, while the other (class III) is not. This study was designed to enumerate the P-gp genes in fish and determine how they are related to the two functional classes already defined in mammals. Southern blot analysis using a conserved single exon from the 3' terminal region of hamster P-gp cDNA (pEX1-172) as a probe indicated that there were two P-gp genes in right-eye flounders. Subsequently, two sets of clones were isolated from a winter flounder genomic library that correspond to the 3' ends of the two flounder P-gp genes. Sequence analysis was done on two key areas: the 3' ATP binding site and the 3' terminal exon, both of which were found to be homologous with their mammalian counterparts. Despite high levels of sequence identity in the predicted coding regions of the gene fragments it has not been possible to use these sequences to relate the homologs to particular mammalian classes of P-gp genes, perhaps because of gene conversion between mammalian P-gp genes. These cloned sequences are the first set of P-gp genes reported in lower vertebrates and will be useful for delineating the expression of P-gp genes in fish and understanding the role of P-gp in fish physiology.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

New specific assays for tonin and tissue kallikrein activities in rat submandibular glands. Assays reveal differences in the effects of sympathetic and parasympathetic stimulation on proteinases in saliva.

At least fourteen separate bands of proteinase activity, labelled A-N, were identified by an enzyme overlay membrane technique, using oligopeptide-7-amino-4-trifluoromethylcoumarin (AFC) substrates in rat submandibular gland extracts fractionated on pH 4-6.5 isoelectric focusing gels. The proteinases were eluted into an ammonium bicarbonate buffer pH 9.8 containing 0.1% Triton X-100 and the relative contribution of each band to total activity evaluated using D-Val-Leu-Arg-AFC (DVLR-AFC) and Z-Val-Lys-Lys-Arg-AFC (ZVKKR-AFC) as substrates. Immunoblotting of band eluants run on sodium dodecyl sulphate gels with antibodies showed that band A was identical with tonin and bands K-N contained tissue kallikrein. Tonin was found to hydrolyse ZVKKR-AFC but not DVLR-AFC. Estimates of the Km values of tissue kallikrein for DVLR-AFC and tonin for ZVKKR-AFC were found to be similar (approx. 20 microM) yet the former enzyme hydrolysed its substrate five times faster. Tonin was inhibited by soybean trypsin inhibitor (SBTI) but not by aprotinin. Tissue kallikrein, on the other hand, was inhibited by aprotinin but was considerably more resistant to inhibition by SBTI. In tissue extracts 95% of the ZVKKR-AFC lytic activity in the presence of 1 microM aprotinin is due to tonin and a similar percentage of the DVLR-AFC hydrolysing activity in the presence of 10 microM SBTI is due to tissue kallikrein. These findings were used for the specific measurement of these two proteinases in submandibular gland extracts and in saliva without prior purification. Using these inhibitor based assays we revealed qualitative differences in the composition of proteinases secreted into saliva during parasympathetic versus sympathetic stimulation of the submandibular gland. The distribution of proteinases in sympathetic saliva is very similar to that found in submandibular extracts but on parasympathetic stimulation, although much less proteinase is released, the contributions of the more acidic isomers of tissue kallikrein are increased and that of tonin and other proteinases dramatically decreased. The data suggest that parasympathetic and sympathetic nerves induce proteinase secretion via different pathways.

Amino Acid Sequence↗
PubMed1992

Secretory oedema in diabetic submandibular glands during parasympathetic nerve stimulation: relationship to microvascular abnormalities in streptozotocin-treated rats.

1. Submandibular secretion during parasympathetic stimulation (5 Hz) was examined in streptozotocin-diabetic and age-matched control rats. 2. At 3 weeks, but not 3 and 6 months, flow rate was initially greater than in controls, but it declined rapidly after 30 min. 3. The reduction in flow rate was associated with oedema of the gland. 4. At 3 months, graded stimulation revealed a tendency to oedema at frequencies of 10 Hz and above. 5. Morphologically, submandibular capillary density was increased in diabetic rats. 6. Thus, in diabetes the submandibular gland appears less able to withstand continuous parasympathetic stimulation, due in part to an increase in tissue capillary area.

Animals↗
PubMed1992

Epilepsy--another cause of intermittent fever with confusion.

The problem of recurring episodes of fever and confusion in an 83 year old man was found to be due to epilepsy. He was treated with carbamazepine which abolished the attacks. Epilepsy-induced fever is a difficult diagnosis to make, and electroencephalogram can be invaluable in making the diagnosis.

Aged↗
PubMed1992

Fracture of the tibial spine in adults and children. A review of 31 cases.

We reviewed 19 adults and 12 children who had been treated for avulsion fractures of the tibial spine. Adult injuries have not previously been reported at length; most were caused by road-traffic accidents, and 68% were associated with other injuries, of which 58% were around the knee. The higher incidence of associated injuries in adults as compared with children, indicates that the injury is the result of greater energy and perhaps a different mechanism. The worse outcome in some adults was due to other associated intra-articular fractures and tears of the medial collateral ligament. Arthroscopy is useful in both diagnosis and treatment. Early accurate diagnosis and the correct treatment produce a good outcome.

Adolescent↗
PubMed1992

Urinary symptoms and urodynamic diagnosis of patients in one geriatric department.

Fifty five patients between 65 and 89 years old who had their urinary problems assessed by urodynamics study were reviewed. The most common urinary symptom among males was urge incontinence, while retention and urge incontinence occurred with equal frequency among females. The commonest cause of retention in males was bladder outlet obstruction, while atonic neurogenic bladder was the most common cause in females. Urge incontinence was strongly associated with an unstable bladder, small bladder volume and Parkinson's disease. Retention of urine, and an atonic neurogenic bladder strongly correlated with diabetes mellitus. Three patients (out of 31) with unstable bladders also had detrusor external sphincter dyssynergia. Of these, two had Parkinson's disease. Although three patients were thought to have stress incontinence after history and physical examination, only two had stress incontinence with detrusor instability on urodynamic studies. The last patient had atonic bladder with overflow.

Aged↗
PubMed1991

[Involvement of the central nervous system in disseminated tuberculosis].

Four weeks after starting tuberculostatic treatment (with isoniazid, rifampicin, streptomycin and pyrazinamide) a 21-year-old man with pulmonary tuberculosis developed symptoms of a radiculomyelopathy as well as mild renal failure. After isoniazid and streptomycin had been discontinued and ethambutol and high doses of vitamin B6 had been added all signs and symptoms improved. However, 4 weeks later tuberculous meningitis occurred which at first seemed to respond to administration of 5 antituberculosis drugs and dexamethasone. But 3 weeks later the patient sustained a partial hemiparesis. Its cause was proven to be a tuberculoma in the region of the brainstem. During further administration of tuberculostatic drugs and glucocorticoids the symptoms gradually receded over 8 months. A 54-year-old man with pulmonary tuberculosis developed cranial nerve pareses and symptoms of cerebellar involvement (trunk ataxia, intention tremor, dysdiadochokinesia) 3 weeks after starting tuberculostatic treatment. Computed tomography revealed multiple intracerebral tuberculomas which gradually shrank with continuation of the tuberculostatic treatment plus glucocorticoids. These two case reports illustrate that in tuberculosis involvement of the CNS can express itself clinically through complex symptoms, sometimes even after the start of tuberculostatic treatment.

Adrenal Cortex Hormones↗
PubMed1991

Arthroscopic distension in the management of frozen shoulder.

We report a prospective study comparing the results of treatment for frozen shoulder by manipulation and physiotherapy, arthroscopic distension and physiotherapy, and physiotherapy alone in 75 patients. The first two gave better results than physiotherapy alone and we recommend arthroscopic distension as a good alternative to manipulation. It is more controllable and gives valuable information about the pathological lesions in the joint.

Adult↗
PubMed1991

Proteinase activities in bovine atrium and the possible role of mast cell tryptase in the processing of atrial natriuretic factor (ANF).

1. Using low salt, Triton X-100 and high salt extracts of bovine atria, two main proteinases were identified by means of fluorogenic oligopeptide substrates. 2. An acidic proteinase, extracted in low salt and Triton X-100 was identified as cathepsin B, but it caused little hydrolysis of the Z-Gly-Pro-Arg- containing substrate that resembles the cleavage site for activation of pro-ANF. 3. An alkaline proteinase was extracted only with high salt and had characteristics of the serine proteinase tryptase. It cleaved Z-Gly-Pro-Arg- containing substrates more efficiently than others tested and was localized in and around mast cells histochemically. Previously, Imada et al., 1988 (J. biol. Chem. 263, 9515-9519) found an identical enzyme would cleave ANF from pro-ANF. 4. These results suggest therefore that mast cell tryptase may be involved in the activation of ANF from pro-ANF.

Amino Acid Sequence↗
PubMed1990

Molecular cloning of an acrosomal sperm antigen gene and the production of its recombinant protein for immunocontraceptive vaccine.

A monoclonal antibody, HS-63, which reacts specifically with a highly conserved sperm acrosome antigen, was shown to inhibit in vitro fertilization of mouse and human. The corresponding sperm antigen designated as MSA-63 was purified to homogeneity from mouse testes and used as an immunogen to generate polyclonal antisera in rabbits. The cDNA fragments of MSA-63 gene were cloned from mouse testis cDNA library by an immunoscreening method using polyclonal antisera specific for MSA-63. Using the established cDNA clone as a probe, the gene encoding for MSA-63 protein was found to be conserved among different mammalian species. Only one specific mRNA 1.5 kb in size was identified from the adult mouse testis among different mouse tissues. The recombinant fusion protein containing MSA-63 protein fragment was produced in Escherichia coli and used to immunize female mice. Similar to the original HS-63 monoclonal antibody, the antisera thus produced reacted only with the sperm acrosome and revealed significant inhibition to the in vitro fertilization of mouse oocytes. The results of this preliminary study suggest that it is feasible to mass produce sperm-specific antigens or their antigenic fragments by recombinant DNA technology for the development of sperm antigen-based immunocontraceptive vaccines.

Acrosome↗