Optimal dynamic incentive scheduling for Hawk-Dove evolutionary games

The Hawk-Dove evolutionary game offers a paradigm of the trade-offs associated with aggressive and passive behaviors. When two (or more) populations of players compete, their success or failure is measured by their frequency in the population, and the system is governed by the replicator dynamics. We develop a time-dependent optimal-adaptive control theory for this dynamical system in which the entries of the payoff matrix are dynamically altered to produce control schedules that minimize and maximize the aggressive population through a finite-time cycle. These schedules provide upper and lower bounds on the outcomes for all possible strategies since they represent two extremizers of the cost function. We then adaptively extend the optimal control schedules over multiple cycles to produce absolute maximizers and minimizers for the system.

803 Management of An Intra-Oral Resection with Integra® Dermal Regeneration Template – Worth A Bite?

Introduction

There are a spectrum of treatment options available for reconstruction of oral mucosal defects including secondary healing, skin grafts, local flaps and microvascular free flaps. We present the use of an alternative intra-oral reconstruction with Integra® Dermal Regeneration Template.

Case Report

An 85-year-old patient with a severe gag reflex and history of oral cancer presented with biopsy proven severe dysplasia of the right palate extending to the hamular notch. She was treated with wide local excision, extraction of teeth, buccal fat pad advancement for closure of an oral-antral communication and placement of Integra® Dermal Regeneration Template. Discharge was possible the same day as the patient was able to eat and had minimal pain.

Discussion

Integra® Dermal Regeneration Template is a bilayer wound matrix consisting of silicone in the outer layer with bovine collagen and glycosaminoglycan from shark cartilage in the inner layer. Oral cancer predominantly affects the older population, and this method can reduce surgical time, remove donor site pain, reduce post-operative pain and avoid use of a cover plate where a strong gag reflex was present. The area heals quickly and aids quick restoration of oral function.

Conclusion

Integra® Dermal Regeneration Template has been used for head and neck defects with good outcomes. It is being increasingly used intra-orally with good outcomes, suggesting a further application of the material with advantages over traditional techniques in specific patient groups.

Electric scooters: convenient transport or ED headache?

Electric scooters (e-scooters) provide a potentially attractive means of private transportation in the pandemic era, during which use of public transport is discouraged. E-scooter use has become widespread recently, and we have noticed a concomitant rise in related craniomaxillofacial injuries, often associated with alcohol consumption and lack of protective equipment. We present here the first-published UK data on electric scooter injuries which, in the post-lockdown period, included facial lacerations, mandibular and midface fractures, avulsed teeth, and cervical spine injury. We urge that forthcoming legislation make e-scooters subject to at least the same requirements in lighting, helmet wear, and sobriety as bicycles and that, in this way, their benefits can be enjoyed while reducing associated morbidity and mortality.

Prenatal diagnosis and management of a craniofacial glioma detected at 20 weeks' gestation. Case report and review of the literature

Foetal imaging and anomaly detection is advancing at a rapid rate. As a result, detection of foetal craniofacial abnormalities is increasing. Ultrasound and magnetic resonance imaging are currently the imaging modalities most commonly used. The authors describe the detection of a nasal glioma at 20 weeks' gestation, subsequent prenatal monitoring and postnatal management with surgical excision at 2 months of age. The world literature regarding prenatal diagnosis and management of craniofacial malformations is discussed.

A study of skin sensitivity to various allergens by skin prick test in patients of nasobronchial allergy

OBJECTIVE

To study skin sensitivity to various allergens in patients of nasobronchial allergy.

MATERIALS AND METHODS

2880 skin prick tests with 60 allergens were performed in 48 patients of nasobronchial allergy.

RESULTS

Most common offending allergens were insects (21.2%), followed by dusts (12.0%), pollens (7.8%), animal dander (3.1%), and fungi (1.3%). The common insect antigen were locust female (33.3%) followed by locust male (25%), grasshopper (20.8%), cricket (16.7%), cockroach female (16.7%) and cockroach male (14.6%). Common dust allergens were house dust, wheat dust, cotton mill and paper dust. Among pollens, Amaranthus spinosus, Argemone mexicana, Adhatoda vasica, Ailanthus and Cannabis were found to be common allergens. In animal danders common offending allergens were cow dander and dog dander. Among fungi Aspergillus fumigatus, Aspergillus flavus, Alternaria teneis and Fusarium sodani were common allergens. Patients of bronchial asthma had associated allergic rhinitis in 80% cases.

CONCLUSION

Common allergens in patients of nasobronchial allergy were identified. The data may prove useful in of allergen avoidance and immunotherapy in these patients.

Tension pneumoventricle following exposure of shunt chamber

Pneumocephalus is the presence of air within the intracranial vault. Intraventricular pneumocephalus, also known as pneumoventricle is relatively rare and commonly occurs following cerebrospinal fluid diversion procedures. This may occur immediately or be delayed. Although a small amount of pneumoventriculus is asymptomatic and may not require any treatment, when present under tension it needs to be evacuated. We present a case of tension pneumoventricle following exposure of the shunt chamber, which resulted in deterioration of the patients' neurological condition and required evacuation.

Patterns of HER-family receptor dimerization in trastuzumab susceptible and trastuzumab resistant cell lines

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Background: HER2 overexpression is associated with accelerated disease progression and poor prognosis in breast cancer. Trastuzumab, a monoclonal antibody targeting the extracellular domain of HER2, is effective in the treatment of metastatic breast cancer. However, most patients treated with trastuzumab eventually develop clinical resistance. To investigate the role of HER-family receptors in trastuzumab resistance, we measured HER-family receptor expression, dimerization, and phosphorylation in trastuzumab susceptible and resistant cell lines. Methods: Cell lysates from trastuzumab susceptible and resistant BT474 and SKBR3 cell lines were obtained from the Arteaga and Esteva laboratories. Proximity-based, multiplexed assays were used to detect and quantify HER1, HER2, and HER3 expression and phosphorylation levels, as well as HER1/HER1, HER1/HER2, HER1/HER3, HER2/HER2, and HER2/HER3 dimers. Samples were incubated with a mixture of HER specific antibodies conjugated either with fluorescent reporter tags (eTags), or biotin, which binds a reporter tag releasing agent (chemical scissor). Reporter molecules are released based on proximity to the scissor in a photochemical reaction and separated by capillary gel electrophoresis. Results: In comparison to trastuzumab susceptible parental cell lines, both SKBR3 and BT474 trastuzumab-resistant cell lines displayed upregulated HER1 expression. Resistant BT474 cell lines exhibited markedly increased levels of HER1/HER2 heterodimers. Increases in HER2 phosphorylation in the trastuzumab resistant SKBR3 cell line were observed, consistent with previous studies implicating trastuzumab in the induction of HER2 phosphorylation. Total HER2 and HER3 levels were similar in trastuzumab susceptible and resistant BT474 cell lines. Conclusions: The development of trastuzumab resistance in these cell line models correlated with HER1 expression and the appearance of HER1:HER2 dimers. Since signaling initiated by such heterodimers is ineffectively antagonized by trastuzumab, these data suggest that selection for proliferative signaling mediated by HER1:HER2 dimers may represent a mechanism of trastuzumab resistance in breast cancer.

No significant financial relationships to disclose.

A comparative evaluation of the tensile strength of silver soldered joints of stainless steel and cobalt chromium orthodontic wires with band material--an in vitro study

The present study was conducted to compare and evaluate the tensile strength of silver soldered joints of stainless steel and cobalt-chromium orthodontic wires with band material. An attempt was made to observe the effect of joint site preparation by incorporation of tack welding and increasing metal to metal surface contact area by flattening an end of the wire prior to soldering along with the regularly used round wires without tack welding. A total of 180 wire specimens were soldered to 180 band specimens. Fifteen samples according to joint site preparation were included for each of the wire groups i.e. Gloria (S.S.), Remanium (S.S.) and Remaloy (Co-Cr) wires of 0.036" in diameter. The findings of the study were suggestive that all three wires may be used for preparing silver soldered joints irrespective of the quality of the wire. However, when subjecting the wire to joint site preparation, Gloria (S.S.) wire showed less tensile strength as compared to Remanium and Remaloy.

Aluminium phosphide exposure: implications on rat brain lipid peroxidation and antioxidant defence system

We investigated the effect of aluminium phosphide exposure (10 mg/kg body weight) on lipid peroxidation and antioxidant defence system in different regions of rat brain. A significant increase in lipid peroxidation in cerebrum, cerebellum and brain stem was observed in aluminium phosphide-exposed rats, which was accompanied by a marked decrease in the activities of antioxidant enzyme, superoxide dismutase and catalase. A decline in the activity of glutathione reductase was also observed, however, no change was seen in the activity of glutathione peroxidase following aluminium phosphide administration. Decreased levels of non-protein thiols and total sulfhydryl groups were also observed after aluminium phosphide treatment. It seems evident that aluminium phosphide exposure significantly enhanced neuronal lipoperoxidative damage with concomitant alterations in the antioxidant defence status thus having serious bearing on the functional and structural status of the central nervous system.

Glioblastoma multiformis, rapidity of growth--importance of repeat CT scan

A case of glioblastoma multiformis (GBM) where lesion appeared within a month of normal CT scan is reported. It emphasises the importance of early CT scan after neurological deterioration particularly in older patients because of rapid growth of glioblastoma.

Subunit interactions within the Saccharomyces cerevisiae DNA polymerase epsilon (pol epsilon ) complex. Demonstration of a dimeric pol epsilon

Saccharomyces cerevisiae DNA polymerase epsilon (pol epsilon) is essential for chromosomal replication. A major form of pol epsilon purified from yeast consists of at least four subunits: Pol2p, Dpb2p, Dpb3p, and Dpb4p. We have investigated the protein/protein interactions between these polypeptides by using expression of individual subunits in baculovirus-infected Sf9 insect cells and by using the yeast two-hybrid assay. The essential subunits, Pol2p and Dpb2p, interact directly in the absence of the other two subunits, and the C-terminal half of POL2, the only essential portion of Pol2p, is sufficient for interaction with Dpb2p. Dpb3p and Dpb4p, non-essential subunits, also interact directly with each other in the absence of the other two subunits. We propose that Pol2p.Dpb2p and Dpb3p.Dpb4p complexes interact with each other and document several interactions between individual members of the two respective complexes. We present biochemical evidence to support the proposal that pol epsilon may be dimeric in vivo. Gel filtration of the Pol2p.Dpb2p complexes reveals a novel heterotetrameric form, consisting of two heterodimers of Pol2p.Dpb2p. Dpb2p, but not Pol2p, exists as a homodimer, and thus the Pol2p dimerization may be mediated by Dpb2p. The pol2-E and pol2-F mutations that cause replication defects in vivo weaken the interaction between Pol2p and Dpb2p and also reduce dimerization of Pol2p. This suggests, but does not prove, that dimerization may also occur in vivo and be essential for DNA replication.

Effects of pH and dose on nasal absorption of scopolamine hydrobromide in human subjects

PURPOSE

The present study was conducted to evaluate the effects of formulation pH and dose on nasal absorption of scopolamine hydrobromide, the single most effective drug available for the prevention of nausea and vomiting induced by motion sickness.

METHODS

Human subjects received scopolamine nasally at a dose of 0.2 mg/0.05 mL or 0.4 mg/0.10 mL, blood samples were collected at different time points, and plasma scopolamine concentrations were determined by LC-MS/MS.

RESULTS

Following administration of a 0.2 mg dose, the average Cmax values were found to be 262+/-118, 419+/-161, and 488+/-331 pg/ mL for pH 4.0, 7.0, and 9.0 formulations, respectively. At the 0.4 mg dose the average Cmax values were found to be 503+/-199, 933+/-449, and 1,308+/-473 pg/mL for pH 4.0, 7.0, and 9.0 formulations, respectively. At a 0.2 mg dose, the AUC values were found to be 23,208+/-6,824, 29,145+/-9,225, and 25,721+/-5,294 pg x min/mL for formulation pH 4.0, 7.0, and 9.0, respectively. At a 0.4 mg dose, the average AUC value was found to be high for pH 9.0 formulation (70,740+/-29,381 pg x min/mL) as compared to those of pH 4.0 (59,573+/-13,700 pg x min/mL) and pH 7.0 (55,298+/-17,305 pg x min/mL) formulations. Both the Cmax and AUC values were almost doubled with doubling the dose. On the other hand, the average Tmax, values decreased linearly with a decrease in formulation pH at both doses. For example, at a 0.4 mg dose, the average Tmax values were 26.7+/-5.8, 15.0+/-10.0, and 8.8+/-2.5 minutes at formulation pH 4.0, 7.0, and 9.0, respectively.

CONCLUSIONS

Nasal absorption of scopolamine hydrobromide in human subjects increased substantially with increases in formulation pH and dose.

Rationally designed anti-HER2/neu peptide mimetic disables P185HER2/neu tyrosine kinases in vitro and in vivo

Monoclonal antibodies specific for the p185HER2/neu growth factor receptor represent a significant advance in receptor-based therapy for p185HER2/neu-expressing human cancers. We have used a structure-based approach to develop a small (1.5 kDa) exocyclic anti-HER2/neu peptide mimic (AHNP) functionally similar to an anti-p185HER2/neu monoclonal antibody, 4D5 (Herceptin). The AHNP mimetic specifically binds to p185HER2/neu with high affinity (KD=300 nM). This results in inhibition of proliferation of p185HER2/neu-overexpressing tumor cells, and inhibition of colony formation in vitro and growth of p185HER2/neu-expressing tumors in athymic mice. In addition, the mimetic sensitizes the tumor cells to apoptosis when used in conjunction with ionizing radiation or chemotherapeutic agents. A comparison of the molar quantities of the Herceptin antibody and the AHNP mimetic required for inhibiting cell growth and anchorage-independent growth showed generally similar activities. The structure-based derivation of the AHNP represents a novel strategy for the design of receptor-specific tumor therapies.

Analysis of the essential functions of the C-terminal protein/protein interaction domain of Saccharomyces cerevisiae pol epsilon and its unexpected ability to support growth in the absence of the DNA polymerase domain

As first observed by Wittenberg (Kesti, T., Flick, K., Keranen, S., Syvaoja, J. E., and Wittenburg, C. (1999) Mol. Cell 3, 679-685), we find that deletion mutants lacking the entire N-terminal DNA polymerase domain of yeast pol epsilon are viable. However, we now show that point mutations in DNA polymerase catalytic residues of pol epsilon are lethal. Taken together, the phenotypes of the deletion and the point mutants suggest that the polymerase of pol epsilon may normally participate in DNA replication but that another polymerase can substitute in its complete absence. Substitution is inefficient because the deletion mutants have serious defects in DNA replication. This observation raises the question of what is the essential function of the C-terminal half of pol epsilon. We show that the ability of the C-terminal half of the polymerase to support growth is disrupted by mutations in the cysteine-rich region, which disrupts both dimerization of the POL2 gene product and interaction with the essential DPB2 subunit, suggesting that this region plays an important architectural role at the replication fork even in the absence of the polymerase function. Finally, the S phase checkpoint, with respect to both induction of RNR3 transcription and cell cycle arrest, is intact in cells where replication is supported only by the C-terminal half of pol epsilon, but it is disrupted in mutants affecting the cysteine-rich region, suggesting that this domain directly affects the checkpoint rather than acting through the N-terminal polymerase active site.

A structural determinant of the unique interfacial binding mode of bovine pancreatic phospholipase A2

The catalytic steps of the phospholipase A2 (PLA2)-catalyzed hydrolysis of phospholipids are preceded by interfacial binding. Among various pancreatic PLA2s, bovine pancreatic PLA2 (bpPLA2) has a unique interfacial binding mode in which Lys-56 plays an important role in its binding to anionic lipid surfaces. To identify the structural determinant of this unique interfacial binding mode of bpPLA2, we systematically mutated bpPLA2 and measured the effects of mutations on its interfacial binding and activity. First, different cationic clusters were generated in the amino-terminal alpha-helix by the N6R, G7K, and N6R/G7K mutations. These mutations enhanced the binding of bpPLA2 to anionic liposomes up to 15-fold. For these mutants, however, the K56E mutation still caused a large drop in interfacial affinity for and activity toward anionic liposomes, indicating that the generation of a cationic patch in the amino-terminal alpha-helix of bpPLA2 did not change its interfacial binding mode. Second, residues 62-66 that form a part of the pancreatic loop were deleted. For this deletion mutant (Delta62-66), which was as active as wild-type toward anionic liposomes, the K56E and K116E mutations (Delta62-66/K56E and Delta62-66/K116E) did not have significant effects on interfacial affinity. In contrast, the K10E mutation showed a much larger decrease in interfacial affinity (10-fold), indicating the deletion of residues 62-66 caused a major change in the interfacial binding mode. Finally, hydrophobic residues in positions 63 and 65 were replaced by bulkier ones (V63F and V63F/V65L) to pinpoint the structural determinant of the interfacial binding mode of bpPLA2. The effects of K10E and K56E mutations on the interfacial affinity and activity of these mutants showed that Val-63 and Val-65 of bpPLA2 are the structural determinant of its unique interfacial binding mode and that relatively conservative substitutions at these positions result in large changes in the interfacial binding mode among mammalian pancreatic PLA2s. Taken together, this study reveals how minor structural differences among homologous PLA2s can lead to distinct interfacial binding behaviors.

Role of the putative zinc finger domain of Saccharomyces cerevisiae DNA polymerase epsilon in DNA replication and the S/M checkpoint pathway

It has been proposed that C-terminal motifs of the catalytic subunit of budding yeast polymerase (pol) epsilon (POL2) couple DNA replication to the S/M checkpoint (Navas, T. A., Zheng, Z., and Elledge, S. J. (1995) Cell 80, 29-39). Scanning deletion analysis of the C terminus reveals that 20 amino acid residues between two putative C-terminal zinc fingers are essential for DNA replication and for an intact S/M cell cycle checkpoint. All mutations affecting the inter-zinc finger amino acids or the zinc fingers themselves are sensitive to methylmethane sulfonate and have reduced ability to induce RNR3, showing that the mutants are defective in the transcriptional response to DNA damage as well as the cell cycle response. The mutations affect the assembly of the pol epsilon holoenzyme. Two-hybrid assays show that the POL2 subunit interacts with itself, and that the replication and checkpoint mutants are specifically defective in the interaction, suggesting (but not proving) that direct or indirect dimerization may be important for the normal functions of pol epsilon. The POL2 C terminus is sufficient for interaction with DPB2, the essential and phylogenetically conserved subunit of pol epsilon, but not for interaction with DPB3. Neither Dpb3p nor Dpb2p homodimerizes in the two-hybrid assay.

Analysis of visual dysfunctions in HIV-positive patients without retinitis

PURPOSE

To investigate visual dysfunctions in ophthalmoscopically normal human immunodeficiency virus (HIV)-positive patients and to correlate the results to the stage of HIV disease and neuropsychological status.

METHODS

Fifty-one randomly selected eyes (26 right, 25 left) of 51 HIV-positive patients with visual acuity measurements of 20/20 or better and no ophthalmoscopically detectable disorders were prospectively examined using achromatic and short-wavelength automated perimetry, color vision testing, and contrast sensitivity testing. CD4+ T-lymphocyte count, presence of systemic infection, hemoglobin, hematocrit, serum beta 2-microglobulin levels, and results of neuropsychological testing were also analyzed.

RESULTS

On achromatic automated perimetry, 21.6% (11/51) of patients performed abnormally according to the mean defect and 27.5% (14/51) according to the Glaucoma Hemifield Test; 29.4% (15/51) performed abnormally on short-wave-length automated perimetry according to the mean defect and 23.5% (12/51) according to the Glaucoma Hemifield Test. On contrast sensitivity, 5.9% (3/51) of patients performed abnormally in the 1.5-cycles per degree (cpd) line, 2.0% (2/51) in the 3-cpd line, 23.5% (12/51) in the 6-cpd line, 25.5% (13/51) in the 12-cpd line, and 33.3% (17/51) in the 18-cpd line. On the Farnsworth-Munsell 100-hue test, 29.4% (15/51) of patients performed abnormally. After correction for multiple correlations, two statistically significant correlations were found: sum of log contrast sensitivity with achromatic automated perimetry and sum of log contrast sensitivity with the Farnsworth-Munsell 100-hue test.

CONCLUSIONS

A significant percentage of HIV-positive patients with visual acuity of 20/20 or better and no ophthalmologic evidence of retinitis performed abnormally on visual psychophysical tests. The severity of visual dysfunction was not correlated with the stage of HIV infection or the degree of neuropsychological dysfunction.

Effect of selenium on lead-induced alterations in rat brain

The effects of lead (Pb) and selenium (Se) interactions on central nervous system (CNS) functions were seen in adult rats by both biochemical and histologic pathological alterations. Pb administration of 20 mg/kg body wt for 8 wk showed degenerative changes only in the cerebral cortex. The changes in the cerebellar regions were not significant. Biochemically a marked decrease in the DNA, RNA, and protein content was seen following lead treatment. These decreases were significant in both the regions of the brain. During the concomitant administration of Pb and Se, the alterations in the transverse section of cerebral cortex showed only marginal changes. The values of DNA and RNA content showed significant improvement in both regions of the brain compared to the Pb treated group.

Transdermal fentanyl system plus im ketorolac for the treatment of postoperative pain

PURPOSE

To assess the safety and efficacy of transdermal fentanyl plus im ketorolac vs im ketorolac alone in the treatment of postoperative pain.

METHODS

Ninety-two patients scheduled for surgery involving moderate to severe postoperative pain were randomized to one of two groups. Group A (n = 46) received an active fentanyl patch and group P (n = 46) received a placebo patch. Patches remained in place for 24 hr. Each patient received intraoperative ketorolac, 60 mg im. Patients were monitored for 36 hr postoperatively and the groups were analyzed for ketorolac usage, pain scores, vital signs, serum fentanyl concentrations, and adverse events. Intramuscular ketorolac was available on demand.

RESULTS

Group A had lower pain scores at 8.12, 16 and 24 hr after patch placement (P < 0.05). Group A had lower heart rates, lower respiratory rates and fewer dropouts due to inadequate pain relief (4.3% vs 21.7% P < 0.05). Group A patients also used less ketorolac than group P patients (P < 0.05). The incidence of pruritus was higher in group A patients (19% vs 2%, P < 0.05), while the incidence of nausea and vomiting was not different between the two groups. Transdermal fentanyl was adequate "stand-alone" analgesia in only 23.8% of group A patients while 93.7% of the remaining group A patients receiving a combination of transdermal fentanyl and ketorolac had adequate pain relief.

CONCLUSION

The transdermal fentanyl delivery system plus ketorolac im was more effective in controlling post-operative pain than ketorolac im alone. The two treatment modalities were comparable in safety with no difference in serious adverse events.

The effect of dietary selenium on lead neurotoxicity

Lead, when administered to male rats for 8 weeks in a dose of 20 mg/kg body weight, resulted in the impairment of the enzymes hexokinase and total ATPase in the cerebral and cerebellar regions of the brain. The changes were, however, more pronounced in the cerebellar region. Along with these, a decrease in acetylcholine esterase (AchE) and monoamine oxidase (MAO) was seen, thus affecting both cholinergic and adrenergic neurotransmitters. When selenium was administered concomitantly with lead, the values of total ATPase and hexokinase activities approached normal values in both brain regions. A significant improvement in acetylcholine esterase activity and MAO was also seen.

Permeation of buprenorphine and its 3-alkyl-ester prodrugs through human skin

PURPOSE

Homologous 3-alkyl-ester prodrugs (C2 to C4) of buprenorphine with decreased crystallinity have been synthesized and evaluated for transdermal delivery commensurate with opioid dependence treatment.

METHODS

To assess the influence of derivatization on delivery, the permeation of the prodrugs through human skin was determined in vitro. Prodrug metabolism was measured in human blood and skin supernatant in vitro along with chemical hydrolysis controls. The prodrugs octanol/water partition coefficients were measured.

RESULTS

Without exception, the prodrugs were completely hydrolyzed on passing through the skin and appeared as buprenorphine in the receptor compartment. However, using saturation conditions, in no instance did the buprenorphine flux through skin from a prodrug solution exceed the flux of buprenorphine base itself in vitro. Moreover, the flux of the acetyl ester, the least hydrophobic of the prodrugs, was not significantly elevated upon stripping the skin. Whether in blood or the skin supernatant, the prodrugs hydrolyzed in an apparent first-order fashion and rate constants and half-lives were calculated.

CONCLUSIONS

We conclude from the results that the prodrugs' very high octanol/water partition coefficients (hydrophobicity) placed them in viable tissue layer controlled diffusion. Consequently, one does not derive the potential flux-increasing benefit of reducing crystallinity that was expected.

Visual field loss in HIV-positive patients without infectious retinopathy

PURPOSE

To determine the extent of vision loss in a cross-sectional study of HIV-positive individuals who had no infectious retinopathy.

METHODS

Visual field loss was determined by computerized achromatic automated perimetry and short-wavelength automated perimetry in both eyes in 65 HIV-positive individuals without infectious retinopathy and in one randomly selected eye each in 57 age-matched normal controls. Results were analyzed using the global index of mean defect and the Glaucoma Hemifield Test, and significance was determined through analysis of variance, chi-square, and Tukey-Kramer tests.

RESULTS

We found that HIV-positive patients, compared with age-matched HIV-negative controls, demonstrated significant (at least P < .01) localized defects as well as an increased mean defect. The HIV-positive patients also had a significantly greater number of defective points, especially on short-wavelength automated perimetry, even while ophthalmoscopic examination and fundus photographs suggested that the retinas were normal.

CONCLUSIONS

There is a significant loss of visual function in HIV-positive individuals that is not the result of infectious retinopathies. The finding by short-wavelength perimetry of more severe defects suggests that the vision defects are not caused by attentional or other suprachiasmatic problems because the neurologic difficulty of both achromatic and short-wavelength perimetry is similar. The effects of this vision loss on the daily living and occupational tasks of this population require further study.

A structure-function study of bovine pancreatic phospholipase A2 using polymerized mixed liposomes

A new combinatorial approach that includes the genetic variation of protein structure and the chemical modification of phospholipid structure in polymerized mixed liposomes was used to delineate the structure-function relationships in the interfacial catalysis of bovine pancreatic phospholipase A2 (PLA2). Based on previous structural and mutational studies, several bovine PLA2 mutants were generated in which a positive charge of putatively important lysyl side chains was reversed (K10E, K53E, K56E, and K116E) or neutralized (K56Q and K116Q). Kinetic parameters of bovine wild type and mutant PLA2s determined using polymerized mixed liposomes consisting of 1-hexadecanoyl-2-(1-pyrenedecanoyl)-sn-glycero-3-phosphoethanolamine (or -phosphoglycerol) and 1,2-bis[12-(lipoyloxy)dodecanoyl]-sn-glycero-3-phosphoglycerol showed that Lys-53 is involved specifically in the interaction with a substrate bound in the active site. Also, these results showed that Lys-10 and Lys-116 are involved in the interaction of bovine PLA2 with anionic interfaces but not in the interaction with the active site-bound substrate. In particular, Lys-116 makes more significant contribution than Lys-10 by approximately 1.0 kcal/mol to the binding to anionic interfaces. Most importantly, Lys-56 was shown to participate in the interaction with both the active site-bound substrate and anionic interfaces. These findings establish Lys-56 and Lys-116 as essential residues for the binding of bovine pancreatic PLA2 to anionic interfaces. Lastly, our structure-function analysis based on the use of polymerized mixed liposomes was further supported by equilibrium binding measurements of these proteins using 1,2-bis[12-(lipoyloxy)dodecanoyl]-sn-glycero-3-phosphoglycerol polymerized liposomes and by kinetic analyses using monomeric substrates, 1,2-dihexanoyl-sn-glycero-3-phosphoethanolamine and -phosphoglycerol.