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Biomedical subjects

R L Williams

Publications and source records attributed to R L Williams.

At least 91 records · Page 5Linked to original sources
PubMed1998

Violence and threats of violence experienced by public health field-workers.

CONTEXT: Public health workers may work with clients whose behaviors are risks for both infectious disease and violence. OBJECTIVE: To assess frequency of violent threats and incidents experienced by public health workers and risk factors associated with incidents. DESIGN: Anonymous, self-administered questionnaires. SETTING: Texas sexually transmitted disease (STD), human immunodeficiency virus and acquired immunodeficiency syndrome (HIV/AIDS), and tuberculosis (TB) programs. PARTICIPANTS: Questionnaires were completed by 364 (95.5%) of 381 public health workers assigned to the programs. The STD program employed 131 workers (36%), the HIV/AIDS program, 121 workers (33%), and the TB program, 112 workers (31%). MAIN OUTCOME MEASURES: The frequencies with which workers had ever experienced (while on the job) verbal threats, weapon threats, physical attacks, and rape, and risk factors associated with those outcomes. RESULTS: A total of 139 (38%) of 364 workers reported 611 violent incidents. Verbal threats were reported by 136 workers (37%), weapon threats by 45 (12%), physical attacks by 14 (4%), and rape by 3 (1%). Five workers (1%) carried guns and/or knives while working. In multiple logistic regression, receipt of verbal threats was associated with worker's male sex (odds ratio [OR], 2.4; 95% confidence interval [CI], 1.5-4.0), white ethnicity (OR, 2.4; 95% CI, 1.4-4.1), experience of 5 years or longer (OR, 2.2; 95% CI, 1.3-3.8), weekend work (OR, 1.8; 95% CI, 1.1-3.1), and sexual remarks made to the worker by clients (OR, 2.0; 95% CI, 1.2-3.5). Receipt of weapon threats was associated with worker's male sex (OR, 5.7; 95% CI, 2.4-15.3), white ethnicity (OR, 4.0; 95% CI, 1.8-9.3), age of 40 years or older (OR, 2.5; 95% CI, 1.1-5.8), work experience of 5 years or longer (OR, 2.7; 95% CI, 1.2-6.0), rural work (OR, 3.6; 95% CI, 1.3-10.1), being alone with the opposite sex (OR, 3.7; 95% CI, 1.6-9.7), and interaction with homeless clients (OR, 5.2; 95% CI, 1.7-18.8). Physical attacks were associated with sexual remarks made to the worker by clients (OR, 4.2; 95% CI, 1.4-13.9). No risk factors predicting rape were identified. CONCLUSIONS: Violence directed toward public field-workers is a common occupational hazard. An assessment of what situations, clients, and locations pose the risk of violence to public health workers is needed.

Adult↗
PubMed1998

Calcium-dependent membrane penetration is a hallmark of the C2 domain of cytosolic phospholipase A2 whereas the C2A domain of synaptotagmin binds membranes electrostatically.

C2 domains have been identified in a wide range of intracellular proteins, including lipid modifying enzymes, protein kinases, GTPases, and proteins involved in membrane trafficking. Many C2 domains bind membranes in a calcium-dependent manner. The first C2 domain from synaptotagmin I (SytIC2A) and the C2 domain from cytosolic phospholipase A2 (cPLA2C2) are among the best characterized C2 domains in terms of their structures and calcium binding. Here we demonstrate that the protein-lipid interaction is dramatically different for these two domains. Photolabeling with 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine ([125I]TID) in the presence of phospholipid vesicles indicates that cPLA2C2 penetrates into the hydrophobic region of the membrane. Hydrophobic surfaces on cPLA2C2 are exposed even in the absence of calcium, but only in its presence does the domain penetrate into the nonpolar core of the membrane. The interaction of SytIC2A with phospholipid membranes is primarily electrostatic with binding being abolished in 500 mM NaCl. Because soluble phospholipid head group analogues do not compete with binding of either SytIC2A or cPLA2C2 to vesicles, it is likely that membrane binding by these domains involves multiple interactions.

Animals↗
PubMed1998

Catalytic domain of phosphoinositide-specific phospholipase C (PLC). Mutational analysis of residues within the active site and hydrophobic ridge of plcdelta1.

Structural studies of phospholipase C delta1 (PLCdelta1) in complexes with the inositol-lipid headgroup and calcium identified residues within the catalytic domain that could be involved in substrate recognition, calcium binding, and catalysis. In addition, the structure of the PLCdelta1 catalytic domain revealed a cluster of hydrophobic residues at the rim of the active site opening (hydrophobic ridge). To assess a role of each of these residues, we have expressed, purified, and characterized enzymes with the point mutations of putative active site residues (His311, Asn312, Glu341, Asp343, His356, Glu390, Lys438, Lys440, Ser522, Arg549, and Tyr551) and residues from the hydrophobic ridge (Leu320, Phe360, and Trp555). The replacements of most active site residues by alanine resulted in a great reduction (1,000-200,000-fold) of PLC activity analyzed in an inositol lipid/sodium cholate mixed micelle assay. Measurements of the enzyme activity toward phosphatidylinositol, phosphatidylinositol 4-monophosphate, and phosphatidylinositol 4, 5-bis-phosphate (PIP2) identified Ser522, Lys438, and Arg549 as important for preferential hydrolysis of polyphosphoinositides, whereas replacement of Lys440 selectively affected only hydrolysis of PIP2. When PLC activity was analyzed at different calcium concentrations, substitutions of Asn312, Glu390, Glu341, and Asp343 resulted in a shift toward higher calcium concentrations required for PIP2 hydrolysis, suggesting that all these residues contribute toward Ca2+ binding. Mutational analysis also confirmed the importance of His311 ( approximately 20,000-fold reduction) and His356 ( approximately 6,000-fold reduction) for the catalysis. Mutations within the hydrophobic ridge, which had little effect on PIP2 hydrolysis in the mixed-micelles, resulted in an enzyme that was less dependent on the surface pressure when analyzed in a monolayer. This systematic mutational analysis provides further insights into the structural basis for the substrate specificity, requirement for Ca2+ ion, catalysis, and surface pressure/activity dependence, with general implications for eukaryotic phosphoinositide-specific PLCs.

Amino Acid Sequence↗
PubMed1998

Structural and mechanistic comparison of prokaryotic and eukaryotic phosphoinositide-specific phospholipases C.

Phosphoinositide-specific phospholipases C (PI-PLCs) are ubiquitous enzymes that catalyse the hydrolysis of phosphoinositides to inositol phosphates and diacylglycerol (DAG). Whereas the eukaryotic PI-PLCs play a central role in most signal transduction cascades by producing two second messengers, inositol-1,4,5-trisphosphate and DAG, prokaryotic PI-PLCs are of interest because they act as virulence factors in some pathogenic bacteria. Bacterial PI-PLCs consist of a single domain of 30 to 35 kDa, while the much larger eukaryotic enzymes (85 to 150 kDa) are organized in several distinct domains. The catalytic domain of eukaryotic PI-PLCs is assembled from two highly conserved polypeptide stretches, called regions X and Y, that are separated by a divergent linker sequence. There is only marginal sequence similarity between the catalytic domain of eukaryotic and prokaryotic PI-PLCs. Recently the crystal structures of a bacterial and a eukaryotic PI-PLC have been determined, both in complexes with substrate analogues thus enabling a comparison of these enzymes in structural and mechanistic terms. Eukaryotic and prokaryotic PI-PLCs contain a distorted (beta alpha)8-barrel as a structural motif with a surprisingly large structural similarity for the first half of the (beta alpha)8-barrel and a much weaker similarity for the second half. The higher degree of structure conservation in the first half of the barrel correlates with the presence of all catalytic residues, in particular two catalytic histidine residues, in this portion of the enzyme. The second half contributes mainly to the features of the substrate binding pocket that result in the distinct substrate preferences exhibited by the prokaryotic and eukaryotic enzymes. A striking difference between the enzymes is the utilization of a catalytic calcium ion that electrostatically stabilizes the transition state in eukaryotic enzymes, whereas this role is filled by an analogously positioned arginine in bacterial PI-PLCs. The catalytic domains of all PI-PLCs may share not only a common fold but also a similar catalytic mechanism utilizing general base/acid catalysis. The conservation of the topology and parts of the active site suggests a divergent evolution from a common ancestral protein.

Amino Acid Sequence↗
PubMed1998

Crystal structure of a calcium-phospholipid binding domain from cytosolic phospholipase A2.

Cytosolic phospholipase A2 (cPLA2) is a calcium-sensitive 85-kDa enzyme that hydrolyzes arachidonic acid-containing membrane phospholipids to initiate the biosynthesis of eicosanoids and platelet-activating factor, potent inflammatory mediators. The calcium-dependent activation of the enzyme is mediated by an N-terminal C2 domain, which is responsible for calcium-dependent translocation of the enzyme to membranes and that enables the intact enzyme to hydrolyze membrane-resident substrates. The 2.4-A x-ray crystal structure of this C2 domain was solved by multiple isomorphous replacement and reveals a beta-sandwich with the same topology as the C2 domain from phosphoinositide-specific phospholipase C delta 1. Two clusters of exposed hydrophobic residues surround two adjacent calcium binding sites. This region, along with an adjoining strip of basic residues, appear to constitute the membrane binding motif. The structure provides a striking insight into the relative importance of hydrophobic and electrostatic components of membrane binding for cPLA2. Although hydrophobic interactions predominate for cPLA2, for other C2 domains such as in "conventional" protein kinase C and synaptotagmins, electrostatic forces prevail.

Amino Acid Sequence↗
PubMed1998

Replacements of single basic amino acids in the pleckstrin homology domain of phospholipase C-delta1 alter the ligand binding, phospholipase activity, and interaction with the plasma membrane.

The pleckstrin homology (PH) domain of phosphatidylinositol-specific phospholipase C-delta1 (PLC-delta1) binds to both D-myo-inositol 1,4, 5-trisphosphate (Ins(1,4,5)P3) and phosphatidylinositol 4, 5-bisphosphate (PtdIns(4,5)P2) with high affinities. We have previously identified a region rich in basic amino acids within the PH domain critical for ligand binding (Yagisawa, H., Hirata, M., Kanematsu, T., Watanabe, Y., Ozaki, S., Sakuma, K., Tanaka, H., Yabuta, N., Kamata, H., Hirata, H., and Nojima, H. (1994) J. Biol. Chem. 269, 20179-20188; Hirata, M., Kanematsu, T., Sakuma, K., Koga, T., Watanabe, Y., Ozaki, S., and Yagisawa, H. (1994) Biochem. Biophys. Res. Commun. 205, 1563-1571). To investigate the role of these basic residues, we have performed site-directed mutagenesis replacing each of the basic amino acid in the N-terminal 60 residues of PLC-delta1 (Lys24, Lys30, Lys32, Arg37, Arg38, Arg40, Lys43, Lys49, Arg56, Lys57, and Arg60) with a neutral or an acidic amino acid. The effects of these mutations on the PH domain ligand binding properties and their consequence for substrate hydrolysis and membrane interactions of PLC-delta1 were analyzed using several assay systems. Analysis of [3H]-Ins(1,4,5)P3 binding, measurement of the binding affinities, and measurements of phospholipase activity using PtdIns(4,5)P2-containing phospholipid vesicles, demonstrated that residues Lys30, Lys32, Arg37, Arg38, Arg40, and Lys57 were required for these PLC-delta1 functions; in comparison, other mutations resulted in a moderate reduction. A subset of selected mutations was further analyzed for the enzyme activity toward substrate present in cellular membranes of permeabilized cells and for interaction with the plasma membrane after microinjection. These experiments demonstrated that mutations affecting ligand binding and PtdIns(4,5)P2 hydrolysis in phospholipid vesicles also resulted in reduction in the hydrolysis of cellular polyphosphoinositides and loss of membrane attachment. All residues (with the exception of the K43E substitution) found to be critical for the analyzed PLC-delta1 functions are present at the surface of the PH domain shown to contain the Ins(1,4,5)P3 binding pocket.

Amino Acid Sequence↗
PubMed1998

Three-dimensional laser imaging system for measuring wound geometry.

BACKGROUND AND OBJECTIVE: A low cost laser imager was designed and fabricated for measurement of wound geometry. METHODS: The accuracy of the imager was validated using reference depressions of known dimensions. Perimeter, area, and volume were compared to planimetric and packing techniques on simulated wound models. RESULTS: Wound tracing and alginate measurement methods required approximately 20 times longer for the reference standards, and 11 times longer for the simulated wounds than with the laser scanning method (LSM). LSM consistently overestimated the reference perimeter by 0.73+/-0.20 cm and the area by 0.98+/-0.62 cm2. Volume estimates were not statistically different. The tracing method underestimated the perimeter by 0.34+/-0.27 cm and the area by 1.07+/-1.09 cm2. Volume measurements by the alginate method were not statistically different. The perimeters of the simulated wounds averaged 1.29+/-0.27 cm greater using the LSM than obtained by the tracing method, and areas greater by 2.02+/-1.30 cm2. Volume scans averaged 1.04+/-0.61 cm3 greater than by the alginate method.

Analysis of Variance↗
PubMed1998

Exchange of perfluorodecalin for gas or oil: a model for avoiding slippage.

BACKGROUND: The introduction of liquid perfluorocarbons as an intraoperative tool has greatly facilitated retinal re-apposition in giant retinal tears (GRT) and relieving retinotomies (RR). Slippage of the retina can occur during the exchange of heavy liquids for oil or gas, especially if the fill of perfluorocarbons is subtotal. METHODS: We have used a model eye chamber to study the surface interactions of perfluorodecalin (PFD) with silicone oil and air to evaluate possible mechanisms of slippage. RESULTS: The results demonstrate that it is possible during a PFD/air exchange to trap a wedge of aqueous which is displaced laterally and forced posteriorly during removal of the PFD, whereas during a PFD/silicone oil exchange the remaining aqueous is displaced laterally and upwards and thus trapped above the silicone oil/PFD interface. CONCLUSIONS: We believe that during PFD/air exchange the displacement of the aqueous posteriorly can cause slippage and that this could be avoided by performing a direct PFD/silicone oil exchange.

Air↗
PubMed1998

MR imaging of suspected acute spinal instability.

Twenty-two patients with suspected acute vertebral instability were imaged within 48 h of injury using a 0.5 Tesla magnet. In all patients plain radiographs, T1 weighted gradient echo (GE) and STIR sequences were performed. Two radiologists blindly evaluated the magnetic resonance imaging (MRI) scans defining injuries with bony or soft tissue disruption of both columns as unstable. Indirect signs of instability such as soft tissue haemorrhage were recorded and correlated where possible with operative findings. Sixteen patients were radiologically unstable on MRI, five more than on plain films alone. Instability was confirmed operatively in 10 patients. The six other patients with unstable injuries were treated conservatively. Two of these patients had evidence of increased deformity before fracture union. The radiologically stable patients were treated as such and at 6-month review showed no evidence of progressive instability. The presence of soft tissue haemorrhage in the interspinous gap was not associated with ligament rupture unless actual discontinuity was demonstrated at that level. We conclude that using MRI acutely, most unstable spinal injuries can be rapidly and accurately evaluated without the need for further imaging.

Acute Disease↗
PubMed1998

Long-term pulmonary sequelae of severe bronchopulmonary dysplasia.

OBJECTIVE: To evaluate the long-term pulmonary sequelae of survivors of bronchopulmonary dysplasia (BPD) of sufficient severity to have required supplemental oxygen for at least 1 month after term. STUDY DESIGN: Fifteen patients with a mean age of 1.1 years were matched to preterm infants of similar gestational age and age at time of study. Pulmonary function testing included spirometry, plethysmographic lung volumes, carbon monoxide diffusion capacity, and in 9 of 15 subjects with BPD, measurement of lung static elastic recoil pressures. RESULTS: The subjects with BPD had a mean expiratory volume in 1 second (FEV1) of 64% +/- 21% predicted (4 had an FEV1 < 50% predicted) compared with 85% +/- 11% (P < .01) for the preterm children in the control group. Subjects with BPD had a significant degree of gas trapping with a residual volume to total lung capacity ratio of 37% +/- 13% compared with 25% +/- 4% for the control group (P < .01). An inverse relationship was seen between the FEV1 and the time on supplemental oxygen (r = -0.84, P < .0001), with 3 of the 4 children whose FEV1 was < 50% requiring oxygen for more than 900 days. Those with the greatest degree of airflow limitation and gas trapping had the greatest abnormalities in both shape and position of the pressure volume curves of the lung. CONCLUSION: Severe BPD may result in moderate to severe long-term abnormalities in pulmonary function tests.

Bronchopulmonary Dysplasia↗
PubMed1998

The relative bioavailability and in vivo-in vitro correlations for four marketed carbamazepine tablets.

PURPOSE: To determine if three marketed generic carbamazepine tablets were bioequivalent to the innovator formulation, as well as to each other. In addition, to examine in vivo-in vitro relationships among the four formulations. METHODS: Each formulation was given as a single dose to 18 healthy male and female subjects using a crossover design. Blood samples were collected for 169 hr. Carbamazepine was assayed by HPLC with UV detection. RESULTS: In vivo fraction absorbed plots indicated that the three generic formulations were absorbed more rapidly than the innovator product, and the mean time of maximum plasma concentration was 6-7 hr sooner for the generic formulations. The mean maximum plasma concentration ranged from 17-19 percent higher for the generic products compared to the innovator, and the 90% confidence limits for Cmax data ranged from 11 1% to 126%. The mean AUC(0-infinity) for the generic products ranged from 101-104% compared to the innovator, and the confidence limits for AUC ranged from 97-108%. CONCLUSIONS: The generic products were all more rapidly absorbed than the innovator, but simulations of steady-state concentrations indicated that it would be unlikely that these differences would have any significant clinical effect. An excellent association was seen between the Cmax and the percent of drug dissolved in vitro. The correlation was used to accurately predict the Cmax of four other 200 mg tablets evaluated in an earlier study.

Adult↗
PubMed1998

Lack of in vivo/in vitro correlations for 50 mg and 250 mg primidone tablets.

PURPOSE: To determine if large differences in the in vitro dissolution profiles for primidone tablets would result in significant bioavailability differences. METHODS: Two separate bioavailability studies were conducted. The first study used 18 healthy subjects and compared the bioavailability of an old 50 mg tablet formulation, a new 50 mg tablet formulation, and a suspension containing 50 mg/ml of primidone. The second study enrolled 24 subjects who were to receive a new 250 mg tablet formulation, two lots of an old 250 mg tablet formulation and a 250 mg tablet from a second manufacturer. In vitro dissolution was conducted over 90 minutes, using USP 23 Apparatus 2 at 50 rpm, with 900 ml of water. RESULTS: Dissolution at 90 minutes for the old and new 50 mg tablets was approximately 20% and 100%, respectively. The dissolution of the four 250 mg tablets ranged from approximately 30% to 100%. The 50 mg tablet that dissolved slower had a longer Tmax and a 14% lower Cmax than the more rapidly dissolving tablet, but the AUC(0-infinity) values differed by only 3%. Only nine subjects completed the 250 mg study because of side effects. The differences in Cmax and AUC(0-infinity) among the four 250 mg tablets were less than 7%. CONCLUSIONS: Even though there were large differences in the in vitro dissolution of the 50 mg and the 250 mg primidone tablets, the two 50 mg tablets were shown to be bioequivalent, as were the four 250 mg tablets.

Adult↗
PubMed1998

Critical success factors for promotion and tenure in family medicine departments.

PURPOSE: (1) To summarize the judgments of family medicine department leaders regarding the elements leading to success in promotion and/or tenure, and (2) to compare the views of department leaders with those of family medicine faculty who have been successfully promoted. METHOD: Two surveys were conducted. The first was of 296 associate professor members of the Society of Teachers of Family Medicine in November 1993. The second, conducted in the summer of 1994, was of all 115 U.S. members of the Association of Departments of Family Medicine; surveys were addressed to chairs, directors, or promotion and tenure committee chairs. Both survey instruments requested data regarding each respondent's department, impressions about the promotion and tenure processes at the respondent's institution, and general impressions regarding the characteristics of successful candidates. Comparisons of the responses to the two questionnaires were made using two-tailed t-tests; responses to open-ended questions were analyzed qualitatively by two independent investigators. RESULTS: In all, 75% of the department leaders and 67% of the associate professors returned completed questionnaires. The two groups had similar views about the importance of certain academic activities to success at promotion and tenure. The primary difference between the groups was in their estimates of weekly time available for research and writing activities: the leaders reported that successful candidates spent a mean of 25% of their work-weeks on research and writing activities; the associate professors, on the other hand, reported spending a mean of 15% of their workweeks on these activities. The department leaders described six basic groups of critical success factors. The associate professors emphasized lack of time as a major obstacle to success. CONCLUSION: The findings emphasize the critical importance of protected time for scholarly activities (such as research and writing) if generalists are to be promoted or tenured.

Career Mobility↗
PubMed1998

Relationship between cerebral blood flow and the development of swelling and life-threatening herniation in acute ischemic stroke.

OBJECT: The purpose of this study was to determine whether cerebral blood flow (CBF) measurements in acute stroke could be correlated with the subsequent development of cerebral edema and life-threatening brain herniation. METHODS: Twenty patients with aggressively managed acute middle cerebral artery (MCA) territory strokes who underwent xenon-enhanced computerized tomography (Xe-CT) CBF scanning within 6 hours of onset of symptoms were retrospectively reviewed. The relationship among CBF and follow-up CT evidence of edema and clinical evidence of brain herniation during the 36 to 96 hours following stroke onset was analyzed. Initial CT scans displayed abnormal findings in 11 patients (55%), whereas the Xe-CT CBF scans showed abnormal findings in all patients (100%). The mean CBF in the symptomatic MCA territory was 10.4 ml/100 g/minute in patients who developed severe edema compared with 19 ml/100 g/minute in patients who developed mild edema (p < 0.05). The mean CBF in the symptomatic MCA territory was 8.6 ml/100 g/minute in patients who developed clinical brain herniation compared with 18 ml/100 g/minute in those who did not (p < 0.01). The mean CBF in the symptomatic MCA territory that was 15 ml/100 g/minute or lower was significantly associated with the development of severe edema and herniation (p < 0.05). CONCLUSIONS: Within 6 hours of acute MCA territory stroke, Xe-CT CBF measurements can be used to predict the subsequent development of severe edema and progression to clinical life-threatening brain herniation. Early knowledge of the anatomical and clinical sequelae of stroke in the acute phase may aid in the triage of such patients and alert physicians to the potential need for more aggressive medical or neurosurgical intervention.

Acute Disease↗
PubMed1998

Wound healing. New modalities for a new millennium.

Common to all studies of wound healing modalities is the need to convert the chronic wound into an acute wound and to maintain the wound in an acute state while subsequently using adjunctive therapy. Hence, precise control and documentation of wound care is extremely important in order to avoid contamination of the effects of a specific modality with the effects of good wound care. Falanga has noted that neuropathy of diabetes has been given wide support as the primary pathogenic component of diabetic ulcers, whereas less recognition has been made of the wound-healing failure component. The therapies discussed in this article considered the wound-healing failure component. Oxygen is a drug. The use of oxygen under normobaric conditions at higher than normal inspired partial pressures is standard operating procedure when clinicians are faced with patients with respiratory embarrassment or heart failure. The use of oxygen under hyperbaric conditions, however, remains estranged from the mainstream thoughts of most clinicians. Abnormally hypoxic wounds may benefit from specific oxygen therapy in hyperbaric dosage ranges. However, correction of abnormal wound oxygen tension alone does not guarantee healing. Hyperbaric studies have been criticized for the lack of well-defined wound care protocols, the absence of precise wound healing measures, and poorly defined wound healing endpoints. Studies with growth factors and human skin equivalents exclude patients typically referred for hyperbaric therapy. Patients referred for hyperbaric therapy often have larger wounds with greater severity of peripheral vascular disease with ABIs < 0.7 and TcPO2 < 30 to 40 mm Hg, are often on medications known to inhibit wound healing (e.g., steroids), or have concomitant medical disorders (collagen vascular disease, renal failure) associated with poor healing. No hyperbaric study has controlled stringently for all of these factors. Nevertheless, HBO2 is more specific and successful for the intended purpose of correction of abnormal tissue oxygen tensions than are growth factors for the intended purpose of growth. Similarly, skin substitutes are limited in their application and have not been tried in patients with ABIs < 0.7 or TcPO2 values < 30 mm Hg. In our view, hyperbaric therapy probably can be combined successfully with allogenic grafts and human skin equivalents in this group of patients. Hyperbaric therapy can generate a sufficient granulation base in which these products should be able to close properly selected wounds successfully. No studies of this combined modality approach exist. Finally, regardless of the modality used to aid in wound closure, long-term outcomes probably depend more on neuropathy and large vessel disease than on microangiopathy and local wound-healing defects. The modalities presented in this article must prove to be both cost effective and practical before they are widely disseminated. Nevertheless, the ability to manipulate the local wound environment is no longer inviolate as was once presumed, and current investigations continue to advance therapeutic options in this most fascinating and challenging discipline.

Diabetic Foot↗
PubMed1998

Cerebral MR imaging in intravascular lymphomatosis.

MR imaging data were reviewed retrospectively in four male patients (32 to 74 years old) with histologically confirmed intravascular lymphomatosis (IVL), a rare, aggressive form of non-Hodgkin lymphoma. MR findings included infarct-like lesions (n = 2), focal parenchymal enhancement (n = 3), dural/arachnoid enhancement (n = 2), and, in one case, nonspecific, patchy foci of increased signal in the white matter on long-TR images. All patients had multifocal lesions. Knowledge of the spectrum of MR imaging features in this unusual disorder may aid in diagnosis and potentially enhance the role of imaging in following response to therapy.

Adult↗