Dating the common ancestor of SIVcpz and HIV-1 group M and the origin of HIV-1 subtypes using a new method to uncover clock-like molecular evolution

Attempts to estimate the time of origin of human immunodeficiency virus (HIV)-1 by using phylogenetic analysis are seriously flawed because of the unequal evolutionary rates among different viral lineages. Here, we report a new method of molecular clock analysis, called Site Stripping for Clock Detection (SSCD), which allows selection of nucleotide sites evolving at an equal rate in different lineages. The method was validated on a dataset of patients all infected with hepatitis C virus in 1977 by the same donor, and it was able to date exactly the known origin of the infection. Using the same method, we calculated that the origin of HIV-1 group M radiation was in the 1930s. In addition, we show that the coalescence time of the simian ancestor of HIV-1 group M and its closest related cpz strains occurred around the end of the XVII century, a date that could be considered the upper limit to the time of simian-to-human transmission of HIV-1 group M. The results show also that SSCD is an easy-to-use method of general applicability in molecular evolution to calibrate clock-like phylogenetic trees.

Advances in diagnosis, treatment, and management of orbital and periocular Wegener's granulomatosis

Ophthalmologists are often in a position to diagnose Wegener's granulomatosis and prevent significant morbidity. The past 2 years have seen advances in diagnosis and management strategies for this condition. Orbital magnetic resonance imaging and histologic profiles have been better characterized. Perhaps the greatest advance has been the recognition of promising therapeutic alternatives to the current standard cytotoxic protocol. Trimethoprim-sulfamethoxazole or methotrexate may be valuable in selected patients with limited forms of Wegener's granulomatosis. Finally, new insights into the mechanisms of disease activation and tissue injury may lead to better treatment and long-term prognosis.

Standards for psychological services in long-term care facilities

Psychologists in Long-Term Care (PLTC), a national network established in 1983, has developed, with input from colleagues and consumers, standards for psychological practice in long-term care facilities. These standards address provider characteristics, methods of referral, assessment practices, treatment, and ethical issues. This article describes the document's development and offers suggestions for its use.

Postural dynamics and the preferred critical boundary for visually guided reaching

How do people choose an action to satisfy a goal from among the actions that are afforded by the environment? In 3 experiments the action modes used by actors to reach for a block placed at various distances from them were observed. In each experiment, when actors were not restricted in how they could reach for the object, the transition from their reaching using only arm extension to a mode of reaching in which they used the upper torso to lean forward occurred at closer distances than each actor's absolute critical boundary, beyond which the former action was no longer afforded. In Experiments 2 and 3 actors' seated posture was varied so that the effect of postural dynamics on the distance at which actors actually chose to make the transition between action modes, the preferred critical boundary, could be examined. The results are consistent with the proposal that the preferred critical boundary reflects the relative comfort of available modes of reaching.

Is a standard regime for anticoagulation with heparin in unstable angina adequate?

AIM

To establish the proportion of patients with unstable angina in whom adequate anticoagulation is achieved using a standard regime of intravenous heparin.

METHOD

A prospective series of 108 Emergency Department attendees over a six-month period with a clinical diagnosis of unstable angina for whom anticoagulation with heparin was prescribed were included in the study. The standard regime was a 5000 unit bolus followed by an intravenous infusion of 1000 units per hour (1200 units if the patient's weight was greater than 80 kg), with subsequent adjustments being made by reference to a nomogram. The activated partial thromboplastin time (APTT) was measured at six and 12 hours after treatment began. Two commonly used criteria for adequate heparinisation were compared: 1. APTT greater than 1.5 times control and 2. APTT in the range of 60-85 seconds.

RESULTS

There were valid data for 90 patients at six hours and 79 at 12 hours. Compared to the criterion for adequate anticoagulation of APTT greater than 1.5 times the control, 25% of patients were subtherapeutic at six hours and 12% at 12 hours. Compared to the criterion APTT greater than 60 seconds, 53% of patients were subtherapeutic at 6 hours and 47% at 12 hours. At 6 hours, 26% of patients were over-anticoagulated as defined as APTT greater than 85 seconds. This had reduced to 13% by 12 hours.

CONCLUSIONS

In the context of recent research suggesting that an APTT of greater than 1.5 times the control is sufficient to reduce complications in unstable angina, our results demonstrate that a standard regime of heparinisation will achieve this goal in the majority of patients within 6 hours of starting heparin therapy. However, if an APTT of 60-85 seconds is the goal, this standard regime is inadequate.

Postural dynamics and the preferred critical boundary for visually guided reaching

How do people choose an action to satisfy a goal from among the actions that are afforded by the environment? In 3 experiments the action modes used by actors to reach for a block placed at various distances from them were observed. In each experiment, when actors were not restricted in how they could reach for the object, the transition from their reaching using only arm extension to a mode of reaching in which they used the upper torso to lean forward occurred at closer distances than each actor's absolute critical boundary, beyond which the former action was no longer afforded. In Experiments 2 and 3 actors' seated posture was varied so that the effect of postural dynamics on the distance at which actors actually chose to make the transition between action modes, the preferred critical boundary, could be examined. The results are consistent with the proposal that the preferred critical boundary reflects the relative comfort of available modes of reaching.

Public health nurses' decision making in Canada, Finland, Norway, and the United States

The purpose of this study was to describe the decision-making processes of 369 public health nurses in Canada, Finland, Norway, and the United States, and to discuss any differences observed among these countries. The results indicate that public health nurses used different decision-making models on the job and that these models varied considerably. Five different decision-making models were identified, each exhibiting features of different decision-making theories. The differences between decision making of public health nurses in different countries were statistically significant. The differences in decision making appear to be due to differences in health care systems in the 4 countries and the nature of the nursing task and context.

A university-affiliated community hospital inpatient geriatrics program functioning in an administrative and educational capacity

OBJECTIVE

To demonstrate an unusual form of inpatient geriatric assessment with unique outcomes.

DESIGN

A prospective evaluation of patients admitted to a community hospital-based inpatient geriatrics unit utilizing traditional members of the assessment team along with educational assessment of nurses and satisfaction profiles of patients and/or families.

SETTING

A non-profit community hospital in Northeast Washington, DC.

PARTICIPANTS

All patients older than age 62 admitted to the 42-bed Geriatric Unit during a 4 1/2 year time period.

MEASUREMENTS

Number of total and category recommendations taken by attending physicians from the Inpatient Geriatric Assessment Team, periodic evaluation of unit nurses' geriatric knowledge base and certification, and patient satisfaction through periodic surveys.

RESULTS

More than 4500 patients have been evaluated during the past 4 1/2 years. The number of recommendations taken by attending physicians has averaged 31.3 to 50.7% during four consecutive chart reviews involving the first 25 consecutive patients for the month each performed every six months (n = 100). The average age of patients evaluated was 77.2 (minimum of 62 and maximum of 97); 67% were females and 33% males. The average number of recommendations communicated per patient was 4.1, and the average number adhered to 1.6/patient. The overall knowledge base and certification in geriatric nursing has increased significantly over a 2.5-year period. Composite monthly unit patient satisfaction survey scores increased as well.

CONCLUSIONS

The program is unique in its development, limitations, and outcomes. Other than the cost of limited geriatric nurse practitioner and faculty salary support, the program has been implemented using only current hospital department personnel. The role of the assessment team is to educate attending nurses and staff physicians. It has not yet been possible to measure objective outcomes. However, the current program also serves the purpose of introducing a new medical program to a community hospital in a nonthreatening way and offers opportunities for research. In addition, the program offers further opportunity for expansion and change.

The impact of restructuring and work design on nursing practice and patient care

The purpose of this study was to examine if registered nurses' (RNs) reports of the structure, work processes and performance of Massachusetts hospitals have changed over a five year period. Responses of 928 randomly selected RNs surveyed in 1989 and 858 randomly selected RNs in 1994 to the RN Quality of Worklife Survey (RNQOWS) were compared. Data analysis was performed with a between-subjects multivariate analysis of covariance, controlling for number of years as an RN and as a member of a collective bargaining unit. Significant differences were found in the variables that measure human resources, administrative motivating conditions, task effectiveness, and efficiency (p < 0.001). The implications of the findings for nursing practice in hospitals is discussed and recommendations are made for further research.

Spontaneous metastasis, proliferation characteristics and radiation sensitivity of fractionated irradiation recurrent and unirradiated human xenografts

PURPOSE

Do tumor cells which survive high dose fractionated irradiation exhibit modified metastasis activity, proliferation kinetics, and/or radiation sensitivity? To address this question experimentally, we have studied three recurrent human tumor xenograft systems.

METHODS AND MATERIALS

Three models were derived from a soft tissue sarcoma (HSTS26T), a colon adenocarcinoma (HCT15), and a glioblastoma (HGL21) which had recurred after 90 Gy, 109 Gy, or 77.4 Gy administered in 30 equal doses, respectively. Their production of spontaneous metastasis and cell proliferation characteristics were studied in early generation xenografts in SCID mice, and were compared to those in their previously unirradiated counterparts. As a control, we have also studied each tumor as a post-surgical recurrence. Specimens from the irradiated recurrent and their unirradiated primary tumors were cultured in vitro and their radiation sensitivity determined by clonogenic assay.

RESULTS

The three irradiated recurrent tumor systems retained the individual histological features of their unirradiated primary xenografts. A lower metastatic incidence was observed in two of the three irradiated recurrent tumor lines in comparison with their unirradiated control tumors and their surgical recurrent counterparts. No significant differences were found between the irradiated recurrent tumors and their unirradiated counterparts with respect to: volume doubling time, growth time, potential doubling time, mitotic index, PCNA index, and SF2 values.

CONCLUSIONS

High dose irradiation given in 30 fractions did not increase the metastatic activity in the three human tumor xenograft systems. Furthermore, the fractionated irradiation did not significantly change their proliferation characteristics and cellular radiation sensitivity.

DNA-protein interactions at the telomeric repeats of Schizosaccharomyces pombe

Gel retardation assays using a probe containing the repeat region of a Schizosaccharomyces pombe chromosomal telomere identified four specific DNA- protein complexes in S. pombe total protein extracts (I, I', IIa and IIb). The proteins responsible for these complexes bound to the telomeric repeat region irrespective of whether or not the repeats were in close proximity to the end of a DNA molecule, and none of them bound strongly to single-stranded DNA. The protein responsible for complex I (TeRF I) was separated from the activity responsible for complexes IIa and IIb (TeRF II) using heparin-Sepharose chromatography. Both factors were efficiently cross-competed by an oligonucleotide containing the 18 bp sequence 5'-GGTTACAGGTTACAGGTT-3', which corresponds to two complete telomeric repeat units. Mutation of the T residues at positions 4 and 11 in the oligonucleotide dramatically reduced binding by TeRF II, but had no affect on binding by TeRF I. The protein responsible for complex I' did not bind strongly to either the wild-type or mutant oligonucleotide.

The effect of whole-body irradiation of nude mice on the tumor transplantability and control probability of a human soft tissue sarcoma xenograft

This study has evaluated the impact of the suppression and recovery of the residual immunity in NCr/Sed nude (nu/nu) mice after whole-body irradiation using xenotransplantability and tumor control probability as the end points. For this investigation the xenograft was a human soft tissue sarcoma (HSTS26T). Two assays, the TD50 (the number of tumor cells required to induce a tumor in 50% of the recipients) and the TCD50 (the radiation dose required to control 50% of tumors) were used. For TD50 assays, tumor cells were injected subcutaneously (sc) into the legs of control and whole-body- irradiated nude mice at 1 day or 4, 8 or 12 weeks after irradiation. For TCD50 assays, tumors were transplanted sc into the legs of nude mice which had not been irradiated or which had been given whole-body irradiation at 1 day or 12 weeks prior to transplantation. The tumors were given single-dose irradiation when they reached 6 mm mean diameter under clamp-hypoxic conditions. The results show that the TD50's of mice receiving the injection 1 day and 4 and 8 weeks after whole-body irradiation were 3.6 to >100 times lower than that of unirradiated mice. Two groups which showed a statistically significant difference in TD50 's were those which received the injection 1 day and 8 weeks after whole-body irradiation (P < 0.01 and P < 0.05, respectively). No difference was found in TD50 values between mice that received injection 12 weeks after whole-body irradiation and those which were not irradiated. The TCD50 values of tumors in nonirradiated mice and in mice which had received whole-body irradiation 1 day and 12 weeks prior to to transplantation were 26.8, 44.1 and 33.9 Gy, respectively. Significantly lower TCD50 values were found in groups of nonirradiated mice or mice which received whole-body irradiation 12 weeks prior to transplantation in comparison with the group of mice that received whole-body irradiation on day 1 (both P < 0.05). No significant difference was found between the TCD50 values of the group of mice that received whole-body irradiation 12 weeks prior to transplantation and those for nonirradiated controls. Our conclusion is that the whole-body irradiation can enhance the transplantability of the HSTS26T tumor in nude mice significantly; this enhancing effect will decrease to the pre-irradiation level by 12 weeks after whole-body irradiation. Also, the suppression and recovery of residual immunity after whole-body irradiation can influence the TCD50 values of the same tumor xenografts in nude mice significantly. The changes in TD50 and TCD50 values correlate with the depletion and recovery of the total splenic lymphoid cell number, and especially in natural killer cell activity. We recommend that further immunosuppression in nude mice is necessary when using this model system for studies of human tumors.

Growth and metastatic behavior of five human glioblastomas compared with nine other histological types of human tumor xenografts in SCID mice

The growth and metastatic behavior of five human glioblastoma multiforme xenografts and nine human xenografts of various histological types were compared in severe combined immunodeficient (SCID) mice. The results demonstrate that the metastatic behavior of the human glioblastoma multiforme xenografts did not differ significantly from a variety of other histological xenografts when evaluated at the same transplantation site in the SCID model. These results are consistent with the hypothesis that the site of glioblastoma multiforme growth influences the extraneural metastatic spread of this disease and lead the authors to suggest that the clinical rarity of distant metastasis is not a fundamental property of these cells. A total of 340 male 7- to 8-week-old SCID mice received subcutaneous transplantation of tumor fragments (21-25 mice per tumor type). The tumor-bearing leg was amputated when the tumor reached a volume of 500 mm3; mice were observed for up to 5 months. There was a trend for a lower take rate, longer latent period, longer volume doubling time (VDT) and growth time (GT) in glioblastoma multiforme as opposed to carcinoma and soft tissue sarcoma xenografts. The highest local recurrence rates (78% and 68%) were observed in two glioblastomas multiforme. Both the glioblastoma multiforme and the other histological xenografts exhibited a widely varying metastatic rate: no correlation was demonstrated between VDT, GT, local control/recurrence, and distant metastasis. These findings show SCID mice to be an attractive model for further biological and preclinical studies of human glioblastoma multiforme.

Comparison of 10% povidone-iodine and 0.5% chlorhexidine gluconate for the prevention of peripheral intravenous catheter colonization in neonates: a prospective trial

The purpose of the study was to compare the efficacy of 10% povidone-iodine with that of 0.5% chlorhexidine gluconate in 70% isopropyl alcohol for the prevention of peripheral intravenous catheter colonization in neonates. This was a multicenter, nonrandomized prospective study in a tertiary neonatal intensive care setting in which povidone-iodine and chlorhexidine gluconate were each used as antiseptic skin preparations over sequential 6-month periods. During the first 6 months of the study when povidone-iodine was in use 9.3% (38 of 408) of catheters were colonized. During the second 6 months of the study when chlorhexidine gluconate was in use, catheter colonization occurred in 4.7% (20 of 418, P = 0.01). Catheter-related bacteremia occurred during only 0.2% (2 of 826) of all catheterizations. Heavy skin colonization before catheter insertion (relative risk, 3.6; 95% confidence interval, 1.9, 7.0), catheterization > or = 72 hours (relative risk. 2.0; 95% confidence interval, 1.01, 3.8) and gestational age < or = 32 weeks (relative risk, 1.8; 95% confidence interval, 1.02, 3.3) increased colonization risk. Ampicillin infusion (relative risk, 0.4; 95% confidence interval, 0.2, 0.7) and 0.5% chlorhexidine gluconate cutaneous antisepsis (relative risk, 0.4; 95% confidence interval, 0.2, 0.8) were factors associated with decreased colonization risk. We conclude that 0.5% chlorhexidine gluconate in 70% isopropyl alcohol appears to be more efficacious than 10% povidone-iodine for the prevention of peripheral intravenous catheter colonization in neonates.

The effect of the overall treatment time of fractionated irradiation on the tumor control probability of a human soft tissue sarcoma xenograft in nude mice

PURPOSE

To study the impact of the overall treatment time of fractionated irradiation on the tumor control probability (TCP) of a human soft tissue sarcoma xenograft growing in nude mice, as well as to compare the pretreatment potential doubling time (Tpot) of this tumor to the effective doubling time (Teff) derived from three different schedules of irradiation using the same total number of fractions with different overall treatment times.

METHODS AND MATERIALS

The TCP was assessed using the TCD50 value (the 50% tumor control dose) as an end point. A total of 240 male nude mice, 7-8 weeks old were used in three experimental groups that received the same total number of fractions (30 fractions) with different overall treatment times. In group 1, the animals received three equal fractions/day for 10 consecutive days, in group 2 they received two equal fractions/day for 15 consecutive days, and in group 3 one fraction/day for 30 consecutive days. All irradiations were given under normal blood flow conditions to air breathing animals. The mean tumor diameter at the start of irradiation was 7-8 mm. The mean interfraction intervals were from 8-24 h. The Tpot was measured using Iododeoxyuridine (IudR) labeling and flow cytometry and was compared to Teff.

RESULTS

The TCD50 values of the three different treatment schedules were 58.8 Gy, 63.2 Gy, and 75.6 Gy for groups 1, 2, and 3, respectively. This difference in TCD50 values was significant (p < 0.05) between groups 1 and 2 (30 fractions/10 days and 30 fractions/15 days) vs. group 3 (30 fractions/30 days). The loss in TCP due to the prolongation of the overall treatment time from 10 days to 30 days was found to be 1.35-1.4 Gy/day. The pretreatment Tpot (2.4 days) was longer than the calculated Teff in groups 2 and 3 (1.35 days).

CONCLUSION

Our data show a significant loss in TCP with prolongation of the overall treatment time. This is most probably due to an accelerated repopulation of tumor clonogens. The pretreatment Tpot of this tumor model does not reflect the actual doubling of the clonogens in a protracted regimen.

Quantitative comparison of xenotransplantation of a human soft tissue sarcoma into the subcutaneous tissue of normal, postincision, and postincision plus indomethacin-treated nude mice

The purpose of this study was to test the hypotheses that (1) surgical wounding can enhance the xenotransplantability of a human soft tissue sarcoma (HSTS26T) into subcutaneous (s.c.) tissue of nude mice, and (2) Indomethacin may reduce the xenotransplantability of this human tumor in the surgical wounding animal model by suppressing angiogenesis. The experimental method was to employ the quantitative transplantation assays (TD50, the number of tumor cells that, on average, would be expected to induce a tumor in 50% of the recipients). After an incisional wound (1.0-1.2 cm long) was made on the right leg of each experimental mouse, tumor cells were inoculated into the surgical wound, or into the contralateral leg at 24 and 72 hr postincision, and in another group tumor cells were inoculated into the wound at 72 hr postincision, plus daily s.c. injection of indomethacin, 2 mg/kg body weight for 8 consecutive days in a separate experiment. Nonincisional mice received the same inoculation as the control groups. The TD50s of surgically wounded groups were 3.5-10.7 times lower than that of the control groups. Significantly lower TD50 values were found in groups of cells inoculated into the surgical wound at 72 hr postincision (P < 0.05 or P < 0.01) and into the contralateral leg at 24 hr postincision (P = 0.05). No significant difference was found between the TD50 values in mice that received cells inoculated at 72 hr postincision plus indomethacin treatment, and those with no wound controls. Our conclusion is that the surgical wound can enhance the xenotransplantability of HSTS26T in nude mice. Indomethacin can decrease this enhancing effect level similar to that in no-wound controls and may prevent tumor recurrence in a surgical wound.

The eye of the beholder: housing preferences of inpatients and their treatment teams

The authors surveyed 80 hospitalized patients with serious mental illness and the patients' treatment teams to compare their perspectives about appropriate housing and support services following hospital discharge. The results showed that the opinions of patients and treatment teams differed markedly on housing preferences but converged on many basic service needs. Patients preferred more independent living arrangements, while treatment teams favored more structured environments. The authors believe that these conflicting views must be reconciled if patient preferences are to be reflected in discharge planning.

Interphotoreceptor retinoid binding protein (IRBP) enhances rhodopsin regeneration in the experimentally detached retina

Results obtained in a previous study showed that, compared with a normal eyecup preparation, the amount of rhodopsin regenerated and the rate at which it was resynthesized after bleaching were reduced by about 50% when the skate retina was detached from its pigment epithelium (RPE) and replaced immediately on the apical surface of the RPE (Sun and Ripps, 1992). In the present study, these observations have been extended to preparations in which the detachment procedure was performed under fluid in order to dilute the IRBP content of the interphotoreceptor matrix. The goal initially was to determine whether lowering the IRBP concentration of the subretinal space affected the regenerative process. Using fundus reflectometry, it was found that allowing fluid to enter the subretinal space exposed by the detachment procedure caused profound deficits in both the rate and amount of rhodopsin that regenerated after bleaching. Results obtained with SDS-PAGE and immunohistochemistry showed that the molecular weight of the IRBP extracted from the skate retina is similar to that of many other vertebrate species, and that antibodies prepared against mammalian IRBP react with epitopes on skate IRBP within the interphotoreceptor matrix. Accordingly, it was investigated whether it is possible to reverse the detachment-induced anomalies in rhodopsin kinetics by introducing ligand-free IRBP purified from bovine retina to the subretinal space. Again using fundus reflectometry, it was found that instilling 5 microM of a 130 microM IRBP solution between the neural retina and the RPE increased significantly the rate of regeneration, and more than doubled the amount of rhodopsin reformed in darkness.

Intratumoral heterogeneity of malignant gliomas measured in vitro

PURPOSE

To evaluate the extent of intratumoral heterogeneity of radiation sensitivity in malignant gliomas, by comparing the intrinsic radiation sensitivity of different glioma sublines derived from the same tumor.

METHODS AND MATERIALS

The study was performed on five early established malignant gliomas (passage 3-10). Each specimen was quickly cut into three equal pieces (except for one specimen, where only two pieces were obtained). Each piece was processed independently, disintegrated into single cell suspension using a cocktail of enzymes. Survival curve assays, using colony formation as an end-point, were performed for each subline. Comparison between the intrinsic radiation sensitivity of sublines was calculated using the surviving fraction at 2 Gy and the mean inactivation dose as the measured parameters. The DNA content of the cell lines as well as their cell cycle analysis was determined using flow cytometry.

RESULTS

The mean calculated surviving fraction at 2 Gy of all the sublines was 0.37 +/- 0.14, the mean mean inactivation dose was 1.98 +/- 0.63. The intertumoral coefficient of variation for the calculated surviving fraction at 2 Gy of all cell lines was 38%, while that for intratumoral heterogeneity was 25%. Three of the 5 tumors showed a statistically significant difference in the surviving fraction at 2 Gy and mean inactivation dose values of their sublines (p < 0.05). This difference in radiation sensitivity between sublines of the same tumor was not attributed to a difference either in the ploidy status or in the distribution of cells in the cell cycle.

CONCLUSION

There is a significant intratumoral heterogeneity of radiation sensitivity in some malignant gliomas. This heterogeneity may limit the predictive power of surviving fraction at 2 Gy or mean inactivation dose, especially when their values are based upon a single measurement/single biopsy. In the meantime, this heterogeneity may be a factor in the discrepancy between unexpectedly sensitive tumor cell lines in vitro and their high clinical radiation resistance.

Behind closed doors

The inside story of how Bill and Hillary Clinton fashioned the health-care plan. Their own aides often battled over the Clintons' approach.

Implementing the Manual Handling Regulations

When last year's consultative document for the Manual Handling Regulations arrived on her desk Maureen Duffy, like many other OHNs, realised that she had her work cut out. She describes how her company set about achieving compliance with the new legislation.

Canadian physiotherapists' professional identity: an exploratory survey

This survey was funded and conducted by the Ontario and Canadian Physiotherapy Association Task Force on Professional Identity. Professional identity influences the image an occupation projects to its clients, the public, other occupations and governments. As an aid to planning strategy for advancing the professional image of physiotherapy, an open-ended questionnaire explored Canadian physiotherapists' professional identity. Professional identity is promoted by Canadian Physiotherapy Association (CPA) branches and districts. Most therapists identified their skills and potential benefit for patients, but only 15% identified themselves as a member of a health profession involved in a rewarding career. Physiotherapists have achieved many characteristics of an independent profession, but expressed frustration reveals that some members lack power on a personal and professional level.

A comparison of excimer laser (308 nm) ablation of the human lens nucleus in air and saline with a fiber optic delivery system

BACKGROUND

Photoablation with excimer lasers has demonstrated precise tissue cutting and minimal thermal damage. Potential ophthalmic applications of these lasers include remodelling of the corneal surface, glaucoma treatment, and phacoablation. Ablation of human lens with a 308 nm XeCl excimer laser light delivered through a fiber has been demonstrated in preliminary experiments. Intraocular delivery of laser light must be done in a fluid medium to preserve the integrity of ocular structures. However, little information is available on the effect of the fluid media on the ablation process. Therefore, a series of experiments was conducted to determine whether the ablation of human lens nucleus at 308 nm via a fiber differs in air and saline media.

METHODS

Ablation of human lens nuclei (n = 30) was conducted with a XeCI excimer laser (308 nm) coupled to a 600 microns core size fiber. Irradiation was performed at 2.8 mJ/cm2 energy density and 20 Hz. The fiberoptic was brought to contact with the lens nucleus and remained fixed for the duration of irradiation. Variables consisted of the medium (air or saline) and number of pulses delivered (100 to 10,000). Following establishment of the tissue shrinkage ratio, the depth of each crater and the tissue volume removed were measured histologically. The histological features of nucleus ablation in air and in saline were also examined with both light and scanning electron microscopy.

RESULTS

Light microscopy revealed that the average zone of thermal damage adjacent to the crater is thinner in the presence of saline (60 microns, SD = 6 microns) than it is in air (90 microns, SD = 12 microns). In both media, the thickness of the zone of thermal damage is greater at the surface than it is at its base. Following irradiation in air, deep sharpedged craters with smooth walls are formed. Craters formed by irradiation in saline are characterized by reduced depth and irregular walls. For the same number of pulses applied (500, 1000, and 2000), the mean depth of ablation per pulse in air (8.6 to 2.7 microns/pulse) was greater by approximately a factor of two than that in saline (4.10 to 1.30 microns/pulse) at P < .01. However, the mean ablated volume removed per pulse was greater in saline (0.00250 to 0.00150 mm3/pulse) than in air (0.00120 to 0.00080 mm3/pulse), for the same number of pulses (1000, 2000) at P < .01.

CONCLUSIONS

In comparing the data for the same number of pulses applied in air and in saline, it appears that the depth of crater formed by irradiation in air is deeper than that in fluid. The overall volume ablated is greater in fluid than it is in air at 1000 and 2000 pulses. Additionally, the zone of thermal damage is thinner in the presence of saline than it is in air. Smoother crater shapes were observed following irradiation in air than in saline. These results suggest that under this specific experimental setup, the ablation in saline is different from that in air.

Diphenylmethane diisocyanate hypersensitivity pneumonitis: a serologic evaluation

We describe the clinical and immunologic evaluation of a steel plant maintenance supervisor who had clinical symptoms consistent with hypersensitivity pneumonitis. No antigen was obvious but after a thorough occupational history and review of the industrial hygiene data, the most likely antigen appeared to be diphenylmethane diisocyanate. Precipitating antibodies were not detected in the worker's serum; however, significant antibody levels of IgG specific for diphenylmethane diisocyanate-human serum albumin were detected by other immunoassays. This case highlights the importance of a thorough occupational history and an aggressive laboratory immunologic evaluation in identifying the offending agent in a worker with hypersensitivity pneumonitis. Hypersensitivity pneumonitis due to an inhaled reactive chemical may be present without precipitins demonstrated in vitro due to the nature of the haptenized chemical protein conjugate or the concentration of IgG antibody.

Multigene families of Cellulomonas flavigena encoding endo-beta-1,4-glucanases (CM-cellulases)

Multiple genes coding for endo-beta-1,4-glucanases (CM-cellulases) have been isolated from a newly discovered highly cellulolytic strain of Cellulomonas flavigena. Clones of C. flavigena DNA were isolated in Escherichia coli and screened for gene expression on CM-cellulose plates staining with congo red. Six clones produced CM-cellulase activity as detected in liquid assays, and on activity gels. They fell into three groups within which the sequences cross-hybridised. There were small differences in the pH and temperature optima of the enzymes encoded by representatives of the three groups of clones.

Being healthy: women's images

Although the concept of health is central to nursing practice and science, measurement of the concept has lagged far behind theory development. The study presented extends Laffrey's earlier work by describing the meaning of health for a population of women representing multiple ethnic groups residing in the Pacific Northwest. A sample of 528 women from a cross-section of a community who had participated in a study of women's health was asked to respond to the question, "What does being healthy mean to you?" In addition to evidence of the clinical, role performance, and adaptive models of health, the women's responses yielded nine dimensions consistent with the eudaemonistic model. Each dimension included multiple descriptors identified through content analysis of the women's verbatim responses. The women's images of health were consistent with Smith's and Laffrey's four conceptions, but the eudaemonistic category included multiple dimensions. The women reported images of health consistent with contemporary nursing theorists' views. Moreover, their emphasis on eudaemonistic images crossed all categories of age, education, income, ethnicity, and employment status.

Analysis of ppb levels of organics in water by means of purge-and-trap, capillary gas chromatography and selective detectors

The Environmental Protection Agency (EPA) has issued a series of methods (500 and 600 series) for the analysis of organics in drinking water and industrial discharges. Methods 601 and 602 employ packed-column gas chromatography (GC) with electrolytic conductivity (E1CD) and photoionization detection (PID), respectively. A purge-and-trap system is used for concentration of volatiles. The EPA is in the process of converting methods 601 and 602 and certain 500-series methods to capillary column analysis. We have also initiated the conversion of a number of these methods, using E1CD and PID and have described them in detail in this paper. We have evaluated both 0.32- and 0.53-mm diameter capillary columns, using helium and nitrogen as carrier gases with each detector. We found that with nitrogen optimum results are obtained at a flow-rate of 15 ml/min, and with helium at 6-8 ml/min. As a result of system optimization, including operation of the two detectors in series, and converting from packed to capillary columns, we found that analysis time could be reduced from 80 min (for two methods separately) to ca. 30 min. In addition, the elution of more than five components in one peak, observed when the packed column specified in method 601 are used, was eliminated.

Activation of blood coagulation in Crohn's disease. Increased plasma fibrinopeptide A levels and enhanced generation of monocyte tissue factor activity

We have examined the relationships among activation of blood coagulation, generation of monocyte procoagulant activity, and clinical activity in patients with Crohn's disease. Subclinical activation of blood coagulation was measured using a radioimmunoassay for fibrinopeptide A. Fibrinopeptide A levels were strongly correlated with the level of disease activity as measured by the Crohn's disease activity index. Patients with active disease who were successfully treated either medically or surgically demonstrated a reduction of fibrinopeptide A levels. Failure of fibrinopeptide A to return to the normal range predicted an early relapse. Monocyte tissue factor generation was assessed in both unstimulated and lipopolysaccharide-stimulated mononuclear cell cultures obtained from the peripheral blood of patients with Crohn's disease. A strong correlation (r = 0.89) was observed between plasma fibrinopeptide A levels and monocyte tissue factor generation. These results suggest that monocyte procoagulant generation may contribute to the activation of blood coagulation in this inflammatory bowel disease. Moreover, fibrinopeptide A levels in Crohn's disease may provide a useful quantitative measure of inflammatory activity.

Social and conversational skills training with long-term psychiatric inpatients

Social and conversational skills training has proven effective with chronic psychiatric populations. Little attention, however, has been directed towards examining the use of this training with individuals who have severe disabilities and have not been released from psychiatric institutions to the community. The present case study examined the utility of this training and constraints in attempting to conduct treatment with two groups of 4 and 3 female psychiatric inpatients who averaged 20 yr. of institutionalization. Significant improvement in orientation and attention, reduction in psychotic talk, and gains on three of five conversational skills were noted. Generalization gains were evident on two of the five specific skills. Observations of group process, examination of indicators of emotional impact, and suggestions for practice are discussed.

Smoking habits of long-term survivors of surgery for lung cancer

The smoking habits of 52 patients who had survived more than five years after treatment for lung cancer were studied. Fifty-six per cent had stopped smoking before operation but this was not an early feature of the disease. No patients smoked in the immediate postoperative period but 48% became regular smokers again, usually within a year of the operation. Those who had stopped before, rather than after, their operation were more likely to remain nonsmokers. Doctors were usually unsuccessful in persuading those patients who had restarted after surgery to stop smoking. Patients undergoing surgery for lung cancer should be advised to stop smoking before the operation. Those in whom resection is successful should receive regular support and encouragement from doctors, especially in the first postoperative year, to continue as nonsmokers.