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Biomedical subjects

K K Lo

Publications and source records attributed to K K Lo.

At least 19 recordsLinked to original sources
PubMed2004

Oriented immobilization of Pseudomonas putida putidaredoxin at a gold (111)-buffer interface: a real time scanning tunnelling microscopy study.

A scanning tunnelling microscopy study of adsorption of wild-type Pseudomonas putida putidaredoxin at a gold (111)-buffer interface has been made in real time. Reversible adsorption has been observed reflecting weak interaction of the wild-type protein with a gold (111) electrode. A genetically engineered mutant, C73S-D58C, which contains a surface thiol, has been used for 'immobilization' and 'orientated adsorption' on the gold surface. The implication of such orientated immobilization in development of a bio-electrode surface has been predicted.

Adsorption↗
PubMed2002

Genotype spectrum of cervical human papillomavirus infection among sexually transmitted disease clinic patients in Hong Kong.

Previous studies have suggested that a few uncommon human papillomavirus (HPV) genotypes are prevalent in Chinese cervical cancer patients. To elucidate the genotype spectrum of HPVs circulating among Hong Kong Chinese, a cross-sectional study was conducted on 553 women who attended a public sexually transmitted disease clinic. HPV DNA was detected from cervical samples using the polymerase chain reaction, followed by genotype identification based on restriction fragment length polymorphism and direct sequencing. The prevalence of HPV was 30.6% for all types combined, 14.8% for high-risk types, 10.8% for low-risk types, and 7.1% for unknown-risk types. Among the HPV-positive women, 89.9% had single type infections; whereas the other 10.1% harboured more than one HPV type. HPV11 was the most prevalent genotype, detected in 5.1% of subjects; followed by HPV16 (4.9%), HPV58 (4.3%), HPV6 (3.3%), and HPV53 and CP8304 (2.2% each). Other less common genotypes found were HPV18, 33, 39, 61, LVX160, MM4, MM7 (range: 0.7-1.6%); HPV26, 45, 54, 56, 59, and LVX100 (range: 0.4-0.5%); HPV35, 40, 52, 55, 68, MM8, and MM9 (0.2% each). This study shows that HPV58 is the second most common high-risk HPV genotype circulating among Chinese female sexually transmitted disease clinic patients in Hong Kong. This together with previous reports of the high prevalence of HPV58 among Chinese cervical cancer patients accentuate the importance of developing vaccines targeting at this otherwise uncommon genotype.

Adult↗
PubMed2001

Porphyria cutanea tarda and melioidosis.

Porphyria cutanea tarda is a metabolic disorder in the haem biosynthetic pathway. It includes a heterogeneous group of conditions, which may be inherited or, more commonly, acquired. Although porphyria cutanea tarda presents with cutaneous lesions only, it is often associated with systemic disease. A 64-year-old Chinese patient, who developed sporadic porphyria cutanea tarda 1 year after the diagnosis of pulmonary melioidosis, is discussed. The patient presented with a history of recurrent photosensitive vesicles, blisters, and skin fragility on the sun-exposed areas of both forearms and hands, 6 months after commencing doxycycline and amoxycillin. Both the histological and biochemical findings were characteristic of porphyria cutanea tarda. All the lesions subsided after cessation of these antibiotics. The patient was free of further lesions at follow-up 6 months later. The association seen in this case between porphyria cutanea tarda and melioidosis is unlikely to be coincidental, because these two diseases are both very rare in Hong Kong. In addition, the temporal relationship between the antibiotic therapy and the clinical course of skin lesions in this patient suggests that the drugs were a trigger factor, precipitating their appearance.

Anti-Bacterial Agents↗
PubMed2000

A scanning tunnelling study of immobilised cytochrome P450cam.

A site-specifically engineered surface cysteine residue, located in a region where the haem moiety is closest to the surface, is used to anchor cytochrome P450cam enzyme molecules covalently to a gold electrode. More reproducibly ordered adsorption, at high coverage, occurs with this K344C mutant than with the wild-type enzyme. The subsequently formed close-packed monolayer arrays have been probed by scanning tunnelling microscopy under ambient conditions and under aqueous (buffered) solution at high resolution. Initial indications suggest that the immobilised enzyme is both electrochemically addressable and catalytically active.

Camphor 5-Monooxygenase↗
PubMed2000

Crusted (Norwegian) scabies in two old-age home residents.

Scabies is commonly seen in hospitals, where it frequently affects geriatric and convalescent patients. The clinical features of the classic form of scabies are well recognised. Crusted (Norwegian) scabies, which is a hyperinfestation variant of scabies, is very contagious and can present as other dermatoses, thus delaying the correct diagnosis and management. Two residents of different old-age homes presented with hyperkeratotic skin eruptions, which later proved to be crusted scabies. In both cases, the scabies was initially misdiagnosed as eczema. The delay in making a correct diagnosis led to an outbreak of scabies in the old-age home in which one of the patients was residing.

Aged↗
PubMed1999

Surface-modified mutants of cytochrome P450cam: enzymatic properties and electrochemistry.

We report the electrochemistry of genetic variants of the haem monooxygenase cytochrome P450cam. A surface cysteine-free mutant (abbreviated as SCF) was prepared in which the five surface cysteine residues Cys-58, Cys-85, Cys-136, Cys-148 and Cys-334 were changed to alanines. Four single surface cysteine mutants with an additional mutation, R72C, R112C, K344C or R364C, were also prepared. The haem spin-state equilibria, NADH turnover rates and camphor-hydroxylation properties, as well as the electrochemistry of these mutants are reported. The coupling of a redox-active label, N-ferrocenylmaleimide, to the single surface cysteine mutant SCF-K344C, and the electrochemistry of this modified mutant are also described.

Animals↗
PubMed1999

A volume adjustable four-coil phased array for high resolution MR imaging of the hip.

A four-coil phased array was specifically designed and built for MR imaging of the hip at 1.5 T. Its RF and imaging properties were evaluated using phantom and in-vivo studies and the results were compared to those of three different commercial coils commonly used for hip imaging. Our coil gave a significantly higher S/N at anatomic locations commonly evaluated for hip diagnosis. The increased S/N supports higher image spatial resolution and improves the visualization of fractures and lateral injuries.

Adult↗
PubMed1999

Surgical pearl: fine gauze is a useful carrier for epidermal graft in the treatment of vitiligo by means of the suction blister method.

Conventional treatments of vitiligo include topical steroids and PUVA, which necessitate prolonged application and frequent clinic visits; response to such treatments also varies. During the past few years, we have used autologous suction-blister-derived epidermal grafts in more than 150 patients with stable localized vitiligo who did not respond to topical steroids and PUVA. Up to now results are promising. In this method, spreading of the epidermal graft to its maximum size and its accurate transferral onto the recipient area are important steps. However, the graft produced by this method is so thin and soft that it wrinkles and curls frequently, making spreading and transportation to the recipient site cumbersome. In our experience with more than 700 grafts, we found that the use of plain fine gauze makes harvesting and transportation of donor grafts technically simple and effective.

Humans↗
PubMed1999

Three Hong Kong Chinese cases of pretibial epidermolysis bullosa: a genodermatosis that can masquerade as an acquired inflammatory disease.

Three patients in two families presented with many years' history of fragile skin, blisters, erosions and scars affecting almost exclusively the shin areas, accompanied by a variable degree of itching. Two of the patients also had toenail dystrophy. Skin biopsy revealed dermal-epidermal blister formation and milia but no immunohistochemical evidence of immunoglobulin or complement deposition. Electron microscopic study of the lesional and perilesional skin showed very sparse or absent anchoring fibrils. Immunolabelling for type VII collagen using LH 7.2 monoclonal antibody revealed a bright, linear staining pattern at the dermal-epidermal junction. The clinicopathological features were thus compatible with pretibial epidermolysis bullosa, a subtype of dystrophic epidermolysis bullosa. Of note, the inflammatory nature of the skin lesions, and their resemblance to nodular prurigo and hypertrophic lichen planus, had caused diagnostic difficulties in all cases in the past. A high degree of awareness of this rare subtype of epidermolysis bullosa is important to establish the correct diagnosis, to allow for genetic counselling and to plan clinical management.

Adolescent↗
PubMed1999

Evaluation on the antipruritic role of transcutaneous electrical nerve stimulation in the treatment of pruritic dermatoses.

BACKGROUND: Pruritus is a common and sometimes distressing symptom in many dermatological conditions. Response to conventional pharmaceutical agents may not be satisfactory, and adverse effects are real problems. OBJECTIVE: To evaluate the short-term efficacy and adverse effects of transcutaneous electrical nerve stimulation (TENS) for ameliorating pruritus in patients with dermatoses. METHODS: A prospective 1-week study using TENS given once daily for treating pruritic dermatoses in 5 patients. RESULTS: Significant amelioration of pruritus was obtained without adverse effect referable to TENS treatment, and a subjective reduced use of conventional topical drugs was also reported by all patients. CONCLUSIONS: TENS is a useful aramentarium for short-term amelioration of pruritus in pruritic dermatoses. Long-term efficacy and safety await further studies.

Adolescent↗
PubMed1999

Multiresolution browsing of pathology images using wavelets.

Digitized pathology images typically have very high resolution, making it difficult to display in their entirety on the computer screen and inefficient to transmit over the network for educational purposes. Progressive zooming of pathology images is desirable despite the availability of inexpensive networking bandwidth. An efficient progressive image resolution refining system for on-line distribution of pathology image using wavelets has been developed and is discussed in this paper. The system is practical for real-world applications, pre-processing and coding each 24-bit image of size 2400 x 3600 within 40 seconds on a Pentium II PC. The transmission process is in real-time. Besides its exceptional speed, the algorithm has high flexibility. The server encodes the original pathology images without loss. Based on the image request from a client, the server dynamically generates and sends out the part of the image at the requested scale and quality requirement. The algorithm is expandable for medical image databases such as PACS.

Algorithms↗
PubMed1998

Colonic diverticulosis in Hong Kong: distribution pattern and clinical significance.

This is a retrospective study on the prevalence of diverticulosis in Hong Kong Chinese adults. Eight-hundred and fifty-eight consecutive barium enema examinations over a period of 18 months (January 1995-June 1996) were analysed. Results show that the prevalence of diverticulosis in our community is 25.1% with no significant difference between male and female adults. The prevalence is lower than Western countries but higher than in Asia. Moreover, the peak prevalence is at the 50-79 years age group with lower prevalence in the older age groups. This may be explained by the rapid rise in prevalence in the younger age groups so that the age-related increase in prevalence become obscured. We postulate that this may be due to Western cultural influence in our diet and lifestyle. There is no significant difference in the symptomatology of patients with and without diverticulosis, supporting the idea that diverticulosis alone is usually asymptomatic. There is predominance of right hemicolon involvement in our subjects, in contrast to the left hemicolon predominance in the Caucasian population. Of patients with diverticulosis, 55.3% have only right-sided involvement and 32.6% have bilateral involvement. Only 12.1% of patients with diverticulosis have exclusively left hemicolon involvement. Caecal and ascending colon diverticula are found in 6.4% and 17.6% of all the adults under study, respectively. Clinicians caring for patients from our community should take note of this high frequency of caecal and ascending colon diverticulosis as caecal and ascending colon diverticulitis is notoriously difficult to diagnose clinically.

Adult↗