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Biomedical subjects

G T Lee

Publications and source records attributed to G T Lee.

At least 19 recordsLinked to original sources
PubMed2006

Oxidative stress during peritoneal dialysis: implications in functional and structural changes in the membrane.

Progressive peritoneal fibrosis, membrane hyperpermeability, and ultrafiltration failure have been observed in patients on long-term peritoneal dialysis (PD). The present study tested the hypothesis that reactive oxygen species (ROS) generated by conventional PD solution (PDS) mediate functional and structural alterations of peritoneal membrane in vivo. Sprague-Dawley rats were randomized to control, PDS, PDS with an antioxidant, and PDS with an angiotensin II (Ang II) receptor blocker. Commercial PDS containing 3.86% glucose (20-30 ml) with or without N-acetylcystein (NAC) 10 mM or losartan 5 mg/kg was administered intraperitoneally twice a day for 12 weeks. Control rats received sham injection. Rats treated with PDS had significantly lower drain volume and D(4)/D(0) glucose, but higher D(4)/P(4) creatinine and increased membrane thickness and endothelial NOS (eNOS) expression compared to control rats. Omental transforming growth factor (TGF)-beta1, vascular endothelial growth factor (VEGF), collagen I, and heat-shock protein (hsp) 47 expression and lipid peroxide levels and dialysate VEGF and Ang II concentrations were significantly increased in rats treated with PDS compared to control. All of these changes were prevented by both NAC and losartan. In conclusion, the present study demonstrates that ROS generated by conventional PDS are, in large part, responsible for peritoneal fibrosis and membrane hyperpermeability. We suggest that antioxidants or Ang II receptor blockers may allow better preservation of the structural and functional integrity of the peritoneal membrane during long-term PD.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2006

The frequency of repeat general anaesthesia for teeth extractions in children.

AIM: The purpose of this study was to determine the frequency of repeat extractions under general anaesthesia (GA) in children. METHODS: The dental hospital records of patients attending for outpatient GA extractions at Liverpool University Dental Hospital, Liverpool, UK, between January and March 2003 were examined retrospectively. A data collection form was used to record the relevant information. RESULTS: A total of 278 patients with a mean age of 6.5 years (SD = 2.2 years) were seen for GA extractions. Of those, 33 patients (11.9%) with a mean age of 4.9 years (SD = 2 years) at the time of their initial GA had had a previous or would undergo a subsequent episode of GA extraction. The mean interval between repeat GA was 2.3 years (SD = 1.6 years). Fifteen cases (45.5%) had the repeat GA within 2 years. Radiographs were available as part of the assessment process for 84 (34.3%) of the 245 patients who had had a single episode of GA. However, of the 33 patients who had had a repeat GA, only seven (21.2%) had radiographs available at the time of the initial GA. Regarding the number of teeth extracted, a significant difference (P < 0.01) was found between the number of teeth extracted in patients who had had a single GA (mean = 4.6, SD = 2.5), compared with those extracted at the initial GA for the repeat GA group (mean = 3.2, SD = 2). CONCLUSION: The frequency of repeat GA is relatively low, but there is a need for appropriate treatment planning incorporating the use of radiographs to reduce this even further.

Adolescent↗
PubMed2006

The use of general anaesthesia for the extraction of children's teeth. Results from two UK dental hospitals.

AIM: To study the reasons forgiving children a general anaesthetic (GA) for the extraction of teeth, in two different paediatric dentistry centres and to compare them with draft guidelines disseminated for discussion by the British Society of Paediatric Dentistry (BSPD). METHODS: Data were collected on children who required GA extractions over a two month period (1st may to 30th June 2004) at the Paediatric Dental Units of Liverpool University Dental Hospital (LUDH) and the University Dental Hospital of Manchester (UDHM). The information collected included date of birth, gender, date of referral, date of assessment and date of GA. The reason for the GA was noted in terms of the proposed BSPD guidelines for short GA. RESULTS: A total of 264 and 268 children required extractions under GA at LUDH and UDHM respectively. At LUDH the main reason in 189 (72%) children was severe pulpitis requiring immediate relief of pain where a child does not have the intellectual maturity to cope with treatment under local analgesia (LA). This was followed by failed extractions under LA in 53 (20%) children. This reason is not listed under the proposed BSPD guidelines. At UDHM the main reason for GA in 114 (42%) children was symptomatic teeth causing pain in more than two quadrants (or in two quadrants necessitating the use of bilateral inferior dental blocks). CONCLUSIONS: There were differences in the clinical rationale for GA between children attending the two centres. Further information is needed to refine the proposed guidelines on the use of GA for dental extractions in paediatric dentistry. The guidelines need to be flexible and updated to reflect changes in practice and service provision.

Anesthesia, Dental↗
PubMed2002

(AC)(n) polymorphism of aldose reductase gene and diabetic microvascular complications in type 2 diabetes mellitus.

Recent studies suggest that the gene encoding aldose reductase, the enzyme that converts glucose to sorbitol, may confer susceptibility to microvascular disease. The aim of this study therefore, was to investigate the relationship between the aldose reductase gene and type 2 diabetic microvascular complications such as diabetic nephropathy and retinopathy. DNA from 127 Korean patients with type 2 diabetes was typed for an (AC)(n) dinucleotide repeat polymorphic marker at the 5'-end of the aldose reductase gene using polymerase chain reaction. No significant difference in the frequency of the putative risk allele Z-2 was found in patients of nephropathy and retinopathy groups compared with the uncomplicated group (32.2, 34.1 vs. 25.1%, respectively, P>0.05). Similarly, no difference was found in the frequency of the putative protective allele Z+2 among any of the study groups. In conclusion, the results of the study in Korean type 2 diabetic patients do not support the hypothesis that polymorphism at the 5' end of the aldose reductase gene contributes to the susceptibility to diabetic microvascular complications.

Aged↗
PubMed2001

Children choosing between general anaesthesia or inhalation sedation for dental extractions: the effect on dental anxiety.

AIM: To compare the levels of dental anxiety experienced by children having dental extractions using general anaesthesia (GA) with those having extractions using local anaesthesia and inhalation sedation (IHS) when offered a programmed choice between the two techniques prior to treatment. DESIGN: Structured interview with child at pre-treatment and at one week (approximately) follow up. SETTING: Community: primary health care centre. SUBJECTS: Children aged 9-15 years referred to a local NHS Trust dental clinic (n = 88). INTERVENTION: Child and parent provided with information about IHS and its benefits over GA for the assistance in tolerating extraction of teeth and provided with a choice of procedure. MAIN OUTCOME MEASURE: An eight question modified child dental anxiety scale. RESULTS: Full information was received from 76 children giving an 86% response rate. Post-operative dental anxiety was lower in children who had chosen (with their parent) IHS in comparison to those who had chosen general anaesthesia (P < 0.05). Dental anxiety remained unchanged in the group who chose to have their extractions under GA. CONCLUSION: Children and their parents who select IHS as opposed to GA to assist in extractions demonstrate less psychological distress.

Adolescent↗
PubMed2001

A case of malignant proliferating trichilemmoma of the scalp with multiple metastases.

We report a case of malignant proliferating trichilemmal tumor showing multiple distant metastases. The patient demonstrated a round mass in the right occipital area for 12 months and the lesion grew rapidly to assume 8 x 6.5 x 4 cm in diameter, with areas of superficial erosion and crusting within the recent 3 months. The entire lesion was removed with a wide surgical excision. It recurred on the neck area 4 months after excision and the lesion was removed with surgical resection again. There was evidence of multiple metastases on CNS and mediastinal lymph nodes after 6 months. The patient was treated with cisplatin and etoposide combination chemotherapy and a partial response was achieved.

Adult↗
PubMed2000

Thrombopoietin is synergistic with other cytokines for expansion of cord blood progenitor cells.

We investigated the effects of recombinant human thrombopoietin (TPO) in combination with various cytokines including erythropoietin (EPO), interleukin-3 (IL-3), interleukin-6 (IL-6), and stem cell factor (SCF) on megakaryopoiesis, and the expansion of CD34+CD41a+ cells from human cord blood CD34+ cells with these cytokines under serum-free conditions. Human cord blood CD34+ cells were cultured in Megacult (Stem Cell Technologies Inc. Vancouver, Canada) in the presence of recombinant growth factors. Colony-forming unit-megakaryocyte (CFU-M) colonies were counted on day 14. CD34+CD41a+ and CD34-CD41a+ cell expansion was analyzed using a serum-free liquid culture system for 7 days with recombinant growth factors. TPO alone had a concentration-dependent effect on megakaryocyte colony growth. At concentrations above 1 ng/ml, TPO supported significant CFU-Meg colony formation in a concentration-dependent manner. The combination of TPO plus other cytokines, including EPO, IL-3, and SCF, resulted in a synergistic enhancement of the number of CFU-Meg colonies, but IL-6 failed to enhance the effect of TPO. The number of CD41a+ cells increased after 7 days in liquid culture of human cord blood CD34+ cells with various cytokines (EPO, IL-3, IL-6, SCF) combined with TPO, but SCF plus TPO only resulted in a significant synergistic increment of CD34+CD41a+ cells compared with TPO alone. The results of the present study indicate that EPO, IL-3, and SCF can be synergistic with TPO to stimulate proliferation of CFU-Meg and suggest that SCF plus TPO can expand CD34+CD41a+ cells to effect the rapid recovery of platelets in patients following stem cell transplantation.

Antigens, CD34↗
PubMed1998

Preliminary validation and reliability of the Modified Child Dental Anxiety Scale.

An 8-question Modified Child Dental Anxiety Scale was developed to assess children's concerns about specific dental procedures. These dental situations include examination, scale and polish, injection, filling, extraction, and relative and general anaesthesia. A question about how the child felt generally when visiting the dentist was also included. Children (n = 314) from two schools in Liverpool, ages 8 to 15 years, completed a questionnaire including the modified scale, Corah's Dental Anxiety Scale, the Dental Fear Survey Schedule for Children, and background questions (age, sex and previous dental experience). The internal consistency was favourable (alpha = .84) and test-retest reliability acceptable. This initial study suggests that the scale may be useful in trials to assess the benefits of interventions to assist children receive dental treatment.

Adolescent↗
PubMed1997

A case of lymphomatoid papulosis occurred simultaneously with Ki-1-positive anaplastic large cell lymphoma.

Lymphomatoid papulosis (LyP) is a chronic self-healing skin eruption that is clinically benign but histologically mimics a malignant lymphoma. However, lymphomatoid papulosis with anaplastic large cell lymphoma responds poorly to medical treatments, including chemotherapies. We experienced a 60-year-old male patient with lymphomatoid papulosis occurred simultaneously with relapsed Ki-1-positive anaplastic large cell lymphoma who was treated with salvage chemotherapy but, unfortunately, failed to be rescued. We report it with a review of the literature.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Needs for dental information of adolescents from an inner city area of Liverpool.

The aim of this study was to determine the needs for dental information of adolescents and investigate the relationship of their desire for information with their opinion of who decides to make an appointment with the dentist (ie parent or child). In-depth interviews were conducted with 10 adolescents (aged 14 to 16 years) to derive questions for a questionnaire to assess dental information needs. One hundred and fifty-eight adolescents of similar age attending a secondary school in Liverpool were invited to complete the questionnaire. The results showed that adolescents are interested in finding out more information on different aspects of dental health which included especially: how to keep their teeth for life, about the best toothpaste, what to do in case they sustain dental injury and whether they required an orthodontic appliance. Another important finding was that more than half of the adolescents (57%) felt that they were responsible for taking decisions for their dental attendance. These children expressed a desire to know more about certain dental matters. Information needs of young people are important because of evidence derived from this study suggesting that acquisitiveness for dental information in this group, has possible implications for future patterns of seeking dental care.

Adolescent↗
PubMed1993

The influence of a two-day recruiting course on groups of fifth and sixth formers.

The fall in applications to dental schools in the UK has resulted in various recruiting strategies. One such move was the introduction of a two-day residential course for fifth and sixth formers which was first instigated in 1989. This paper describes the course which had been run on four occasions with a total of 160 participants. The results of a survey on the impressions of the course by these participants is reported. It appears that the courses are effective in increasing interest in dentistry in the vast majority of participants.

Adolescent↗
PubMed1993

Changes in the myelinated axons of femoral nerve in amyotrophic lateral sclerosis.

Myelinated fibres in femoral nerves removed from amyotrophic lateral sclerosis (ALS) cases at post mortem were compared with age matched controls. A technique for processing whole transverse sections of the nerves for osmication and subsequent morphometric analysis is described. Although areas depleted in myelinated fibres were seen in the nerves from the ALS group, no statistically significant difference was shown due to wide variations in the controls. However, the ALS nerves showed a degree of disruption in the myelin which was not apparent in the controls. The most obvious effect was widespread "wrinkling" of the myelin in both large and small fibres from the ALS nerves. This phenomenon is the initial stage of a process which eventually results in uneven myelin thickness and nodal swellings and finally myelin ovoids and balls. We illustrate the steps in the progression of this degeneration with teased nerve studies and electron microscopy and propose that there are qualitative changes in the myelin of peripheral nerve in ALS. It seems likely that these are secondary effects resulting from axonal degeneration caused by deterioration and loss of anterior horn cells in the spinal cord.

Amyotrophic Lateral Sclerosis↗
PubMed1991

Childhood leukemia and dental considerations.

Leukemia is the major form of cancer in children in Britain and mirrors the percentage of children affected in the USA. This report outlines some of the medical aspects of leukemia and its treatment and gives a guide to the dentist, who may have the responsibility of dealing with leukemic children and their families.

Child↗
PubMed1989

Remineralization of artificial caries-like lesions in human enamel in situ by chewing sorbitol gum.

The objective of the study was to determine quantitatively the effect on the potential for in situ remineralization of artificial caries-like lesions in human enamel when sugar-free gum containing mainly sorbitol as sweetener was chewed after meals and snacks. Artificial white-spot lesions were created in extracted human premolars and divided into three parts. One part was used as reference and the other two worn consecutively for two 21-day periods by 10 volunteers in a cast silver band cemented on lower molar teeth and covered with gauze to promote plaque formation. During the experimental periods, the subjects used fluoridated toothpaste twice daily, and consumed three meals (breakfast, lunch, and dinner) and two snacks (selected from chocolate bar, raisins, chocolate wafer, and iced cupcake). Sorbitol gum was chewed for 20 min immediately after each meal or snack during one of the experimental periods. The three parts of the enamel lesions were then sectioned (congruent to 80 microns) and examined together by means of quantitative microradiography and by polarized light microscopy. All estimates of mineral content indicated that significant remineralization occurred and was approximately doubled with gum-chewing. It is suggested that sorbitol gum stimulates salivation, which is responsible for the significantly enhanced remineralization, thus contributing to a therapeutic, caries-preventive effect. Because the gum was chewed immediately after meals and snacks, inhibition of demineralization may also have occurred.

Adult↗
PubMed1989

Disruptive behavior during dental treatment of uncooperative children.

This study examines the pattern of behavior of children referred to the Liverpool Dental Hospital for previous lack of cooperation during dental treatment. During a normal treatment session a proportion of these patients refused to allow treatment to proceed. Comparisons were made of the behavioral profiles obtained from detailed observation of treatment by videotape recordings between children who refused or accepted treatment with a comparison group of children. Refusers were characterized by behavior, which prevented treatment from continuing, e.g., closing their mouths and by weeping. Increased levels of restlessness and verbal complaints were not found in the refusers compared with the other children who received treatment.

Child Behavior↗
PubMed1986

Monoclonal antibody CI-panHu defines a pan-human cell-surface antigen unique to higher primates.

The murine monoclonal antibody CI-panHu reacts strongly with the cell surface of all human cells, including erythrocytes, tumour cells and HLA-A,B,C-negative cell lines. As such, this antibody defines the first pan-human cell-surface antigen reported. The antigenic determinant detected is associated with a protein doublet of 16,000 MW whose expression is restricted to cells from humans, apes and some species of Old World monkeys. Antibody reactivity is not diminished by routine fixation procedures, nor by paraffin-embedding, and the antigenic determinant is relatively protease-resistant. The use of this antibody as a positive control in immunoassays of human cells is discussed.

Animals↗
PubMed1985

Novel rearrangements of herpes simplex virus DNA sequences resulting from duplication of a sequence within the unique region of the L component.

We constructed insertion mutants of herpes simplex virus type 1 that contained a duplication of DNA sequences from the BamHI-L fragment (map units 0.706 to 0.744), which is located in the unique region of the L component (UL) of the herpes simplex virus type 1 genome. The second copy of the BamHI-L sequence was inserted in inverted orientation into the viral thymidine kinase gene (map units 0.30 to 0.32), also located within UL. A significant fraction of the progeny produced by these insertion mutants had genomes with rearranged DNA sequences, presumably resulting from intramolecular or intermolecular recombination between the BamHI-L sequences at the two different genomic locations. The rearranged genomes either had an inversion of the DNA sequence flanked by the duplication or were recombinant molecules in which different regions of the genome had been duplicated and deleted. Genomic rearrangements similar to those described here have been reported previously but only for herpes simplex virus insertion mutants containing an extra copy of the repetitive a sequence. Such rearrangements have not been reported for insertion mutants that contain duplications of herpes simplex virus DNA sequences from largely unique regions of the genome. The implications of these results are discussed.

Base Sequence↗