Thresholds for treatment in cataract surgery

BACKGROUND

The aim of the study was to identify the criteria used by ophthalmologists when assessing patients who may require cataract surgery, examine the extent of variation in their application and explore their relationship with current patterns of supply and demand.

METHODS

This was a descriptive study involving semi-structured interviews with ophthalmologists, examination of hospital clinical records, and analysis of routinely available data on waiting times and hospital activity. The setting was ophthalmology units within the Northern Region of England. The subjects were 27 consultant ophthalmologists and 160 patients undergoing cataract extraction.

RESULTS

There was agreement amongst ophthalmologists on the criteria used to select patients for treatment, and on the visual acuity level at which they would usually recommend surgery. All assess the degree of handicap resulting from cataract; most consider this more important than visual acuity. Over half of the patients were over 75 years old; two-thirds were women. Median visual acuity at listing was 6/36, but over 40 per cent were 6/60 or worse. Visual acuity at treatment was not recorded for 32 per cent of patients. Wide variation in visual acuity at listing existed between both units and consultants, and for both the affected and other eye. Second extractions may be performed at a better level of visual acuity than for first extractions. Median visual acuity at listing was significantly correlated with total waiting times for individual consultants. Lower cataract extraction rates are associated with long waiting times and poorer visual acuity at listing.

CONCLUSIONS

There is considerable unmet need for cataract treatment within the Northern Region and significant variation in the current meeting of needs and demands. It may be that more needs could be met simply by changing referral and treatment patterns without increasing total service activity. Although visual acuity is a reasonably objective measure in routine use, the level of visual handicap is more important, and its assessment is more subjective; development of a standard method to assess this could help in producing guidelines for patient referral and selection. Audit of treatment thresholds could allow a better matching of service provision to population needs.

Effect of inhibiting leukocyte integrin (CD18) and selectin (L-selectin) on susceptibility to infection with Pseudomonas aeruginosa

Leukocyte (WBC) adherence to endothelial cells has been implicated in the pathogenesis of microvascular injury. The process of leukocyte adherence is mediated by both the integrin and selectin families of molecules, and their interaction with specific endothelial ligands. Antibodies directed against the leukocyte integrin CD18 and L-selectin have been developed and functionally inhibit leukocyte adherence in models of inflammatory injury. We asked the question: Does inhibition of leukocyte adherence by administration of monoclonal antibody directed against either CD18, integrins (R15.7, R7.1) or against L-selectin (DREG 200) increase susceptibility to infection? New Zealand white rabbits were shaved and injected subcutaneously on their dorsum with Pseudomonas aeruginosa (ATCC#27853) at two sites each of 10(8) and 10(7) colony forming units. Animals were monitored with daily determination of weight, temperature, WBC counts, hematocrit, and killed at 1 week for determination of abscess formation. There were four blinded experimental groups: (1) Saline (2 mL/kg); (2) DREG 200 (2 mg/kg); (3) R7.1 (2 mg/kg); or (4) R15.7 (2 mg/kg). At the 10(7) and 10(8) injection sites the R15.7 group had an increased rate and size of abscess formation compared with controls. The R7.1 group had an increased rate at the 10(8) injection site. There was no significant difference in the percentage of the abscess formation or mean area between the controls and DREG 200-treated groups. We conclude that giving antibody to CD18 increased susceptibility to infection while giving antibody to L-selectin does not.

Inhibition of leukocyte adherence in a rabbit model of major thermal injury

Leukocytes and the process of leukocyte adherence have been implicated in the pathogenesis of organ dysfunction after ischemic injury and inflammation. We asked the question: Will inhibition of leukocyte adherence by administration of a monoclonal antibody to intercellular adhesion molecule alter the systemic response to major thermal injury? New Zealand white rabbits instrumented to measure mean arterial pressure, cardiac output, urine output, and arterial oxygenation were deeply anesthetized, and 30% total body surface area full-thickness burn was created by applying brass probes heated to 100 degrees C to the animals' backs for 15 seconds. The animals were continuously monitored, resuscitated, and given analgesic for 24 hours. There were three experimental groups: I-controls (n = 7), anesthetized and monitored; II-30% burn (n = 7) given 30% total body surface area + vehicle (saline solution 1.0 ml/kg every 8 hours); III-30% burn + R6.5 (n = 6) animals given a monoclonal antibody (R6.5, 2.0 mg/kg every 8 hours) directed against the intercellular adhesion molecule beginning 30 minutes after burn. This model of a 30% total body surface area burn injury resulted in hypotension and hypoxemia in the burn group. The animals given the antibody R6.5 maintained higher mean arterial pressure and arterial oxygenation at several points. These results suggest that leukocytes and leukocyte adherence may be involved in the pathogenesis of the systemic sequellae of major thermal injury.

Changes in exogenous surfactant in ventilated preterm lamb lungs

Preterm lambs were treated with either a surfactant from bovine lung (Survanta) or three synthetic surfactants (Exosurf), a 69:22:9 mixture of dipalmitoylphosphatidylcholine, phosphatidylglycerol, and palmitic acid prepared by heat annealing (Lipid Mixture 1) or with glass beads (Lipid Mixture 2). After 5 h of ventilation, large and small aggregate surfactant fractions were isolated from alveolar washes by centrifugation. SP-A was used as an indicator for the association of endogenous surfactant components with the treatment surfactants. The large aggregate fraction from Survanta-treated lambs contained more SP-A than did the fractions from the lambs treated with the other surfactants (p < 0.05). The surfactants used to treat the sheep and the large aggregate surfactants from alveolar washes increased compliances when tested in surfactant-deficient, immature rabbits, relative to that in control animals. The large aggregate fractions in alveolar washes from lambs treated with Survanta, Lipid Mixture 1, and Lipid Mixture 2 improved compliances in the preterm rabbits to a greater extent than did the surfactants used to treat the lambs. The small aggregate fractions were inactive as surfactants. The function of exogenous surfactant can be improved after exposure to the preterm lung. The improvement may result from the association of exogenous surfactant with components of endogenous surfactant.

Inhibition of leukocyte adherence and susceptibility to infection

Leukocyte (WBC) adherence to endothelial cells (EC) has been implicated in the pathogenesis of microvascular injury. WBC-EC adherence is largely dependent on interaction between the WBC-CD18 complex and the endothelial ligand, intercellular adhesion molecule-1 (ICAM-1). Administration of monoclonal antibodies directed against CD18 and/or ICAM-1 inhibit WBC-EC adherence and have been reported to modulate ischemia-reperfusion and inflammatory injury. We asked the question, does inhibition of WBC-EC adherence by administration of monoclonal antibody directed against either CD18 (R15.7) or against ICAM-1 (R6.5) increase susceptibility to infection. New Zealand white rabbits were shaved and injected subcutaneously on their dorsum with Staphylococcus aureus (ATCC No. 25923) at two sites each with 10(9), 10(8), 10(7), and 10(6) colony-forming units (CFUs). A second set of rabbits were injected subcutaneously with Pseudomonas aeruginosa (ATCC No. 27853) at two sites each of 10(8) and 10(7) CFUs. Animals were monitored for 1 week with daily determination of weight, temperature, WBC counts, hematocrit, and gross evidence of abscess formation. There were three blinded experimental groups; animals given R15.7 (2.0 mg/kg), animals given R6.5 (2.0 mg/kg), and controls given saline (2.0 ml/kg). Administration of the anti-CD18 antibody, R15.7, resulted in significantly increased rates of abscess formation following innoculation with S. aureus and with P. aeruginosa, compared to controls and to the animals given the antibody to ICAM-1, R6.5. The administration of R6.5 did not increase the incidence or severity of abscess formation.

Structure and functions of a dimeric form of surfactant protein SP-C: a Fourier transform infrared and surfactometry study

Surfactant proteins SP-B (M(r) = 8700, reduced) and SP-C (M(r) = 3000-6000, major form, non-reduced) interact with surfactant phospholipids to enhance their surface active properties. In the present study, we describe the structural and functional characteristics of a novel dimeric form of bovine SP-C (M(r) = 9000, non-reduced), which is identified as [SP-C]2. Dimeric SP-C exhibits surface tension-lowering properties differing from those of monomeric SP-C and enhances the surface properties of bovine SP-B/phospholipid mixtures. Chemical analysis indicated that [SP-C]2 was not acylated at the cysteinyl residues. Fourier transform-infrared spectroscopy (FT-IR) was utilized to determine the secondary structures of [SP-C]2 in DPPC films. Relative percentages of alpha-helical, beta-sheet, beta-turn and random coil structures were calculated by peak fit analysis of the amide I band of the FT-IR spectra indicating that, in contrast to the helical structure of monomeric SP-C, [SP-C]2 exhibits almost exclusively beta-sheet structure. In addition, only 10% of the amide (backbone) hydrogens exchanged with deuterium of D2O, indicating that the remaining 90% of amide hydrogens were not accessible to D2O due to strong hydrogen bonding or their location in a hydrophobic environment. Dimerization of SP-C effects a major change in secondary structure, a factor which may play a role in the interaction of SP-C with phospholipids in pulmonary surfactant.

Inhibition of leukocyte-endothelial adherence following thermal injury

Progressive microvascular damage in the tissue adjacent to a cutaneous burn injury results in extension of burn size. The role of neutrophils (PMNs) in the pathogenesis of microvascular injury was investigated by inhibition of PMN adherence to the microvascular endothelium using monoclonal antibodies directed to the leukocyte CD18 adhesion complex or its endothelial ligand, intercellular adhesion molecule-1 (ICAM-1, CD54). A model of thermal injury was developed using New Zealand White rabbits. Under general anesthesia two sets of three full-thickness burns separated by two 5 x 30-mm zones were produced by applying brass probes heated to 100 degrees C to the animals' backs for 30 sec. Cutaneous blood flow determinations were obtained for 72 hr. Blood flow measurements were performed using a laser doppler blood flowmeter (PF3, Perimed, Piscataway, NJ). There were five experimental groups; controls given saline alone, n = 12; animals given monoclonal antibody to the PMN CD18 complex, R 15.7 prior to burn injury (pre-R15.7, n = 5); animals given R 15.7 30 min after burn injury (post-R 15.7, n = 6); animals given the anti ICAM-1 antibody, R 6.5 prior to burn (pre-R 6.5, n = 6); and animals given the R 6.5 30 min postburn injury (post-R 6.5, n = 6). BF in the marginal "zone of stasis" between burn contact sites was significantly higher in the antibody-treated animals and administration of the antibodies 30 min after injury was as effective as preburn administration in preserving blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of surfactant-associated protein SP-B synthetic analogs on the structure and surface activity of model membrane bilayers

The effect of several synthetic peptides based on the sequence of human pulmonary surfactant-associated protein B (SPB) on the molecular packing of model membrane lipids (7:1 dipalmitoyl phosphatidylcholine (DPPC)/dipalmitoyl phosphatidylglycerol (DPPG)) was studied using fluorescence anisotropy. This information was then correlated with complementary biophysical data obtained on both a modified Wilhelmy-Langmuir balance and a pulsating bubble surfactometer. The SP-B peptides examined in these studies are synthetic human SP-B Phe1-Ser78 (SP-B 1-78, full-length sequence), synthetic human SP-B Phe1-Thr60 (SP-B 1-60), synthetic human SP-B Phe1-Ala20 (SP-B 1-20), synthetic human SP-B Ala20-Thr60 (SP-B 20-60), synthetic human SP-B Leu27-Ser78 (SP-B 27-78), synthetic human SP-B Leu40-Thr60 (SP-B 40-60) and synthetic human SP-B Tyr53-Ser78 (SP-B 53-78). trans-parinaric acid was utilized to detect changes in ordering of lipids within the interior upon incorporation of synthetic SP-B peptide, whereas 1-hexadecanoyl-2-[N-(7-nitro-2-benzoxa-1,3-diazol-4-yl)-a min ohexanoyl] phosphatidylcholine (6-NBD-PC) and 1-acyl-2-[N-(7-nitro-2-benzoxa-1,3-diazol-4-yl)aminohexanoyl ] phosphatidylglycerol (6-NBD-PG) were utilized to determine alterations in lipid order at the surface of the model membrane bilayer. With the exception of SP-B 40-60, which corresponds to the most hydrophobic segment of the full-length SP-B, none of the other peptide significantly perturbed the interior bilayer as determined by fluorescence anisotropy of trans-parinaric acid. Incorporation of any of the peptides with the exception of SP-B 40-60, resulted in an increase in anisotropy of NBD-PC. The most significant enhancements resulted from the addition of SP-B 1-78, SP-B 1-20, SP-B 27-78 or SP-B 53-78. The magnitude of anisotropy increase with these peptides is similar to that observed with an equivalent molar ratio of native SP-B isolated from a bovine source. These observations suggest that these four synthetic peptides have the structural and compositional characteristics required for surface ordering of the membrane bilayer in a manner similar to that observed with native SP-B, thereby facilitating the surfactant-like properties of phospholipid mixtures.

Race and child abuse

Very little is known about the relationship between race and child abuse. Skills in prevention, detection and family support have not increased at the same pace as for the majority population. This article looks at some of the factors associated with child abuse in black and ethnic minority communities and suggests how health professionals can improve their skills in working with this section of our population.

Brucellosis in an inuit child, probably related to caribou meat consumption

A 9-year-old Inuit boy with brucellosis is presented. The most likely source of his infection was contaminated caribou meat. Brucella suis is enzootic in Canadian caribou herds and this case indicates that natives of the Arctic are a risk group for acquiring brucellosis through the ingestion of raw caribou meat.

Racial inequalities in health: a challenge to the British National Health Service

The existence of racial inequalities in health in the United Kingdom is examined using both indirect and direct data. The evidence strongly supports the view that the health experience of black and other ethnic minority groups is worse than that of the indigenous white population. Ways of improving this situation are outlined; they indicate the need for a coordinated Health service response incorporating planning, training, and equal opportunities in both service provision and employment practices.