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Biomedical subjects

M Lavin

Publications and source records attributed to M Lavin.

At least 19 recordsLinked to original sources

Hydrophilic expanders for the congenital anophthalmic socket.

The congenitally contracted socket often poses a challenging management problem; early surgery may be necessary in spite of the attendant difficulties. A series of patients is presented, with particular emphasis upon the use of a new hydrophilic expander in the severely contracted socket, to illustrate our current management protocol. Factors pertinent to orbital development and growth are discussed. Two types of contracted sockets are identified that appear to correlate with the presence or absence of an eye or ocular remnant. Use of a hydrophilic expander in the severely contracted anophthalmic socket with marked lid phimosis has enabled subsequent fitting and retention of a hard conformer in many of these cases, thus obviating early interventional surgery.

Adolescent

Advanced uncontrolled glaucoma. Nd:YAG cyclophotocoagulation or tube surgery.

Forty-five patients with advanced uncontrolled glaucoma who had had noncontact neodymium:YAG (Nd:YAG) cyclophotocoagulation were matched and compared with 45 patients who underwent tube implantation surgery. The matching was based on selected criteria, including diagnosis, number of previous operations on the index eye, number of previous glaucoma operations, aphakia, vitrectomy, and age. The drop in intraocular pressure (IOP) was statistically significant in each of the 2 groups at 1, 4, 6, and 12 months of follow-up (P less than 0.001). The tube patients needed fewer antiglaucoma medications at 1 year (P less than 0.025) and more surgical intervention for IOP control, although this was not statistically significant (P greater than 0.1). Laser treatment was repeated in 49% of cases, and age younger than 40 years was identified as a risk factor for poor response to this mode of therapy. The effect on visual acuity and the expected complications also are discussed.

Adult

Heterogeneity in Alzheimer's disease: evidence from cellular radiosensitivity and complementation of this phenotype.

Radiosensitivity was studied in a series of Alzheimer's disease (AD) patients and normal controls by examining clonogenic survival and radiation-induced chromosome aberrations in lymphoblastoid cell lines. D0 values based on colony survival for AD and normals following exposure to gamma-rays were 0.86 +/- 0.04 and 1.14 +/- 0.03 Gy respectively. However, 2 of the AD cell lines had D0 values in the normal range. This increased radiosensitivity in AD cells was confirmed by an increased number of gamma-ray-induced chromosome aberrations in these cells. Cell fusion was employed to investigate the presence of different complementation groups for the radiosensitive phenotype in AD using frequency of radiation-induced chromosome aberrations as a means of distinguishing different groups. Four complementation groups were found among 5 AD cell lines. These findings provide additional experimental evidence in support of heterogeneity in AD.

Aged

Vertebral artery dissection resulting in locked-in syndrome.

A 30 year-old man admitted to the hospital two weeks following a motor vehicle accident developed "locked-in" syndrome resulting from traumatic vertebral artery dissection. Aggressive nursing interventions during the acute and early recovery periods were implemented with the hope that both physical and emotional deficits might be alleviated. Although the prognosis for this type of injury is often poor, this patient has improved steadily over a 16-month period.

Accidents, Traffic

The bistratenes: new cytotoxic marine macrolides which induce some properties indicative of differentiation in HL-60 cells.

The biological effects of cytotoxic macrolide polyethers, the bistratenes, isolated from the ascidian Lissoclinum bistratum, have been examined. Bistratene A was toxic to HL-60 human promyelocytic leukemia cells with an IC50 value of 424 nM. At lower concentrations (10-100 nM), bistratene A induced the incomplete differentiation of these cells along the monocyte/macrophage pathway. These effects were not due to inhibition of DNA synthesis. Bistratene B had similar effects to bistratene A. At micromolar concentrations these compounds enhance the phospholipid-dependent activity of type II protein kinase C from bovine spleen. The bistratenes provide new probes for studying the molecular mechanisms governing cell growth and differentiation.

Acetamides

Serous retinal detachment following glaucoma filtering surgery.

We report the occurrence of serous retinal detachment in association with choroidal effusion and hypotony in six eyes that had undergone glaucoma filtering surgery. Hypotony with choroidal effusion was documented in five patients before the onset of serous retinal detachment. While one patient underwent vitrectomy, treatment was conservative in the other patients. Serous retinal detachment and choroidal effusions resolved spontaneously as the intraocular pressure normalized. Although one patient regained preoperative visual acuity, all other patients lost at least one line of Snellen acuity.

Adolescent

Let the patients smoke: a defence of a patient privilege.

I examine two kinds of arguments in favour of imposing restrictions on smoking by hospitalised psychiatric patients. First, I look at patient-centered arguments in favour of restrictions. These arguments focus on the benefits that patients will receive if their smoking is stopped or curtailed. Second, I examine arguments that seek to justify restrictions by citing the costs that smokers impose on others. Neither kind of argument justifies any meaningful restrictions on the smoking of hospitalised psychiatric patients.

Behavior Control

Delayed suprachoroidal haemorrhage after glaucoma operations.

Delayed suprachoroidal haemorrhage occurred in 13 eyes in a consecutive series of 432 cases undergoing trabeculectomy or anterior chamber (A/C) tube drainage operations. Aphakia and vitrectomy were associated with an increased risk of haemorrhage, whilst advanced age, myopia, systemic hypertension and high preoperative intraocular pressure were not. Haemorrhage occurred more often after A/C tube drainage operations than after trabeculectomy. An explanation for this may be that eyes requiring A/C tube drainage operations have had multiple previous operations including lens extraction and vitrectomy, have a higher pre-operative intraocular pressure and a greater fall in pressure after operation when compared to eyes undergoing trabeculectomy. Post-operative hypotony should be avoided in high-risk eyes.

Adolescent

Anaerobically regulated aldolase gene of maize. A chimaeric origin?

The sequence of the anaerobically induced fructose 1,6-bisphosphate aldolase gene of maize is presented. Analysis of the upstream sequences of the aldolase gene reveals a six base-pair sequence (TGGTTT) with perfect homology to one of the sub-regions of the anaerobic regulatory element (ARE) which is responsible for the anaerobic induction of the maize alcohol dehydrogenase 1 gene (Adh1). In the aldolase gene this sequence is located at position -70 relative to the start of transcription, in a small segment proven by functional analysis to be important for expression of the aldolase gene. Since this six base-pair sequence has been shown to be critical for anaerobic induction of the Adh1 mRNA, is in the functional promoter region of aldolase and is also present in a homologous position in Adh2 (another anaerobically-induced gene), we suggest this hexanucleotide is essential for anaerobic regulation of each of these genes. The maize aldolase gene is about 50% homologous at the amino acid level to the animal aldolase gene but has a completely different intron/exon structure. While the rat aldolase gene has nine introns the maize gene has a single large intron near the N terminus of the coding region. Because there is 55% homology downstream from the intron and very little homology upstream, we suggest that the maize gene has acquired a 5' region containing signals for anaerobic regulation and fortuitously adding a new N-terminal region to the protein. We must suppose that the plant gene has lost the remaining introns.

Anaerobiosis

Integration of bovine leukaemia virus in the ovine genome.

Circulating lymphocytes and tumour cells from 12 sheep experimentally infected with bovine leukaemia virus (BLV), for periods of time varying from 9 to 48 weeks, were analysed for evidence of integrated and unintegrated provirus. Hybridization analysis demonstrated that the provirus was integrated at one or two sites in all cases. Integration was observed at different sites in the animals studied and there was no evidence of unintegrated virus molecules in infected sheep lymphocytes or tumour cells. The data obtained support a monoclonal origin of different tumours in the same sheep.

Animals

What doctors should call their patients.

The paper discusses the moral difficulties physicians encounter when determining the level of formality they will use when addressing their patients. It is argued that physicians ought not to use a patient's first name unless the patient also uses the physician's first name. In short, physicians and patients should always address each other with the same level of formality. It is argued that this is so even when patients invite physicians to address them informally.

Personal Autonomy

Dependence on cloning method of survival of human melanoma cells after ultraviolet and ionizing radiation.

The resistance of a human melanoma cell line (MM96) to both ultraviolet and ionizing irradiation was compared by two different methods of cloning, on plates and in agar. A high level of resistance to both ultraviolet (D0 = 320 ergs/sq mm) and ionizing irradiation (D0 = 4300 rads) was observed when viability of cells was determined by cloning in agar. In contrast, melanoma cells were found to be as sensitive as were other cells when viability after irradiation was determined by cloning on plastic plates. The difference in sensitivity to radiation between the two methods of cloning can be explained in a model involving damage to membranes as well as to DNA. At least for ionizing radiation, this effect is not restricted to melanoma cells since a HeLa subline, HeLa-QB1, showed a similar response. In contrast, a human lymphoblastoid line (JHP) cloned in agar was sensitive under these conditions (D0 = 120 rads).

Agar

Control of DNA repair linked to neuroblastoma differentiation.

Mouse neuroblastoma cells, which can be induced to undergo reversible differentiation in culture, have been used as a model to investigate the effects of ultra-violet (U.V.) radiation on terminally-differentiated nerve cells. Differentiated neuroblastoma cells were found to be extremely sensitive to U.V.-radiation when compared with proliferating cells from the same clone. However, normal resistance was regained if the differentiated cells were allowed to proceed to the next G1 phase of the cell-cycle before irradiation. Neuroblastoma cells in the differentiated mode are capable of carrying out soem excision repair of DNA damage, but they appear to lack a repair mechanism present in proliferating cells.

Cell Division

Resistance of human melanoma cells to ultraviolet radiation.

A series of five human melanoma cell lines has been demonstrated to be highly resistant to ultraviolet (UV) radiation, with a D0 of 400 ergs/sq mm. Melanotic melanoma cells were found to increase their production of melanin following UV radiation, whereas some amelanotic cells did not. Melanotic and amelanotic melanoma cell lines exhibited the same UV resistance; melanoma and nonmelanoma cells formed the same numbers of thymine dimers at a given UV dose. These data imply that melanin does not play a major role in protecting DNA of melanoma cells against UV damage in culture. The rates of removal of thymine dimers from DNA of melanoma cells were comparable to those in UV-sensitive, nonmelanoma cell lines, so that rapid excision repair does not explain UV resistnace in the melanoma cells. No DNA strand breakage was detected in a melanoma cell line at moderate UV doses.

Cell Line