Colour-coded duplex assessment alone before carotid endarterectomy

This study assessed whether carotid colour-coded duplex imaging can provide sufficient information to investigate patients before carotid endarterectomy. One hundred patients with symptomatic carotid artery disease (amaurosis fugax 24, transient ischaemic attack 38 and established stroke 38) were assessed by both colour-coded duplex imaging and arch angiography. Stenoses were graded at angiography using the linear method from the European Carotid Surgery Trial and on duplex using peak systolic velocity criteria. Angiograms were also analysed for any arch or intracerebral pathology which would alter surgical management. In defining 70-99 per cent stenoses, duplex had a sensitivity of 98 per cent, specificity 96 per cent, positive predictive value of 96 per cent, negative predictive value 98 per cent and accuracy 97 per cent compared with angiography for both symptomatic and asymptomatic carotids (chi 2 = 1.22, 1 d.f., P = 0.25). With respect to the symptomatic carotid arteries angiography gave different information from duplex in six patients (6 per cent): definition of 70-99 per cent carotid stenosis was different (four), visualization was poor on duplex (one) and an intracerebral aneurysm was identified by angiography. One patient died following arch angiography as a result of mesenteric thrombosis. Carotid duplex imaging alone would appear to be sufficient to assess most patients before carotid endarterectomy as an accurate, safe and relatively cheap investigation compared with angiography. In cases where duplex assessment does not allow full visualization of the carotid bifurcation angiography is required.

Caulobacter Lon protease has a critical role in cell-cycle control of DNA methylation

CcrM, an adenine DNA methyltransferase, is essential for viability in Caulobacter crescentus. The CcrM protein is present only in the predivisional stage of the cell cycle, resulting in cell-cycle-dependent variation of the DNA methylation state of the chromosome. The availability of CcrM is controlled in two ways: (1) the ccrM gene is transcribed only in the predivisional. cell, and (2) the CcrM protein is rapidly degraded prior to cell division. We demonstrate here that CcrM is an important target of the Lon protease pathway in C. crescentus. In a lon null mutant, ccrM transcription is still temporally regulated, but the CcrM protein is present throughout the cell cycle because of a dramatic increase in its stability that results in a fully methylated chromosome throughout the cell cycle. Because the Lon protease is present throughout the cell cycle, it is likely that the level of CcrM in the cell is controlled by a dynamic balance between temporally varied transcription and constitutive degradation. We have shown previously that restriction of CcrM to the C. crescentus predivisional cell is essential for normal morphogenesis and progression through the cell cycle. Comparison of the lon null mutant strain with a strain whose DNA remains fully methylated as a result of constitutive expression of ccrM suggests that the effect of Lon on DNA methylation contributes to several developmental defects observed in the lon mutant. These defects include a frequent failure to complete cell division and loss of precise cell-cycle control of initiation of DNA replication. Other developmental abnormalities exhibited by the lon null mutant, such as the formation of abnormally long stalks, appear to be unrelated to altered chromosome methylation state. The Lon protease thus exhibits pleiotropic effects in C. crescentus growth and development.

Increased neural cell adhesion molecule in the CSF of patients with mood disorder

Neural cell adhesion molecule (N-CAM) is involved in cell-cell interactions during synaptogenesis, morphogenesis, and plasticity of the nervous system. Disturbances in synaptic restructuring and neural plasticity may be related to the pathogenesis of several neuropsychiatric diseases, including mood disorders and schizophrenia. Disturbances in brain cellular function may alter concentrations of N-CAM in the CSF. Soluble human N-CAM proteins are detectable in the CSF but are minor constituents of serum. We have recently found an increase in N-CAM content in the CSF of patients with schizophrenia. Although the pathogenesis of both schizophrenia and mood disorders is unknown, ventriculomegaly, decreased temporal lobe volume, and subcortical structural abnormalities have been reported for both disorders. We have therefore measured N-CAM concentrations in the CSF of patients with mood disorder. There were significant increases in amounts of N-CAM immunoreactive proteins, primarily the 120-kDa band, in the CSF of psychiatric inpatients with bipolar mood disorder type I and recurrent unipolar major depression. There were no differences in bipolar mood disorder type II patients as compared with normals. There were no significant effects of medication treatment on N-CAM concentrations. It is possible that the 120-kDa N-CAM band present in the CSF is derived from CNS cells as a secreted soluble N-CAM isoform. Our results suggest the possibility of latent state-related disturbances in N-CAM cellular function, i.e., residue from a previous episode, or abnormal N-CAM turnover in the CNS of patients with mood disorder.

A cell cycle-regulated bacterial DNA methyltransferase is essential for viability

The CcrM adenine DNA methyltransferase, which specifically modifies GANTC sequences, is necessary for viability in Caulobacter crescentus. To our knowledge, this is the first example of an essential prokaryotic DNA methyltransferase that is not part of a DNA restriction/modification system. Homologs of CcrM are widespread in the alpha subdivision of the Proteobacteria, suggesting that methylation at GANTC sites may have important functions in other members of this diverse group as well. Temporal control of DNA methylation state has an important role in Caulobacter development, and we show that this organism utilizes an unusual mechanism for control of remethylation of newly replicated DNA. CcrM is synthesized de novo late in the cell cycle, coincident with full methylation of the chromosome, and is then subjected to proteolysis prior to cell division.

Localized facial telangiectasias following frostbite injury

Two patients presented with localized facial telangiectasias a consequence of superficial frostbite injury. Trauma from frostbite resulted in the permanent formation of these telangiectasias. We review the morphology of the different degrees of frostbite and discuss the involvement of angiogenesis as a response to tissue insult.

In vivo examination of membrane protein localization and degradation with green fluorescent protein

To test the utility of green fluorescent protein (GFP) as an in vivo reporter protein when fused to a membrane domain, we made a fusion protein between yeast hydroxymethylglutaryl-CoA reductase and GFP. Fusion proteins displayed spatial localization and regulated degradation consistent with the native hydroxymethylglutaryl-CoA reductase proteins. Thus, GFP should be useful in the study of both membrane protein localization and protein degradation in vivo.

Culture of dialysis fluids on nutrient-rich media for short periods at elevated temperatures underestimate microbial contamination

Recommended culture methods for monitoring bacterial contamination of H2O, dialysate and bicarbonate concentrate in dialysis centers in the USA involves culturing these fluids for 48 h at 37 degrees C. A variety of media and commercial culture methods are accepted for monitoring these fluids. Over a 3-month a comparison was made between an acceptable culture method, tryptic soy agar (TSA) employing the pour plate (PP) technique at 37 degrees C for 48 h, and PP cultures on standard methods agar (SMA) and R2A agar, incubated at ambient temperature (23 degrees C) for 48, 72, 168 h. Increases in the colony counts over time occurred for all three fluids. However, counts wee greater on SMA and R2A than on TSA. The increases over the standard 48-hour TSA cultures ranged as high as 10(4) times for 23 degrees C cultures at 7 days of incubation. Endotoxin levels even in the most contaminated samples were found to be below the acceptable 5 EU/ml recommended for reprocessor water. Bacterial colonies that appeared at 48, 72 and 168 h were isolated and identified. Pseudomonas, Moraxella, Acinetobacter and CDC group VI C-2 were among some of the common bacteria isolated. This study indicates that the media utilized, the time and temperature of incubation may result in a significant underestimation of the bacterial population of water and dialysis fluids, thus potentially placing the patient at a higher risk.

Degradation of HMG-CoA reductase-induced membranes in the fission yeast, Schizosaccharomyces pombe

Elevated levels of certain membrane proteins, including the sterol biosynthetic enzyme HMG-CoA reductase, induce proliferation of the endoplasmic reticulum. When the amounts of these proteins return to basal levels, the proliferated membranes are degraded, but the molecular details of this degradation remain unknown. We have examined the degradation of HMG-CoA reductase-induced membranes in the fission yeast, Schizosaccharomyces pombe. In this yeast, increased levels of the Saccharomyces cerevisiae HMG-CoA reductase isozyme encoded by HMG1 induced several types of membranes, including karmellae, which formed a cap of stacked membranes that partially surrounded the nucleus. When expression of HMG1 was repressed, the karmellae detached from the nucleus and formed concentric, multilayered membrane whorls that were then degraded. During the degradation process, CDCFDA-stained compartments distinct from preexisting vacuoles formed within the interior of the whorls. In addition to these compartments, particles that contained neutral lipids also formed within the whorl. As the thickness of the whorl decreased, the lipid particle became larger. When degradation was complete, only the lipid particle remained. Cycloheximide treatment did not prevent the formation of whorls. Thus, new protein synthesis was not needed for the initial stages of karmellae degradation. On the contrary, cycloheximide promoted the detachment of karmellae to form whorls, suggesting that a short lived protein may be involved in maintaining karmellae integrity. Taken together, these results demonstrate that karmellae membranes differentiated into self-degradative organelles. This process may be a common pathway by which ER membranes are turned over in cells.

Oral immunization with attenuated Salmonella expressing human sperm antigen induces antibodies in serum and the reproductive tract

Induction of immune responses in the reproductive tract will be crucial for a functional gamete antigen-based antifertility vaccine. Here we describe the construction and development of an avirulent Salmonella as an oral vaccine delivery vector to elicit sperm-specific immune responses in reproductive tract secretions. A cDNA sequence encoding the human sperm antigen SP10 was cloned on an asd+vector and expressed to a high level in an avirulent delta cya, delta crp, and delta asd vaccine strain of Salmonella typhimurium. Oral immunization of female BALB/c mice with this recombinant Salmonella elicited high-titer anti-SP10 IgG antibodies in serum and IgA antibodies in vaginal secretions. Anti-SP10 antibody titers could be increased by secondary and tertiary oral administrations of the recombinant Salmonella. Induction of sperm-specific antibodies in the reproductive tract following oral administration of a recombinant Salmonella could lead to the development of a simple, safe, efficient, and easy-to-use antifertility vaccine.

Teleradiology

Advances in telecommunications and computer software have led to the development of radiology image transfer systems. Radiologists may now report radiographs at a site distant from that of the examination, in some cases almost instantaneously. Computed tomography, magnetic resonance imaging, and ultrasonography may also be supervised from afar. Developments over the past few decades are reviewed, allowing an understanding of the systems currently available. These include systems that transmit static images and real time video systems that enable interactive supervision from a radiologist at a distant site. The implications for the practice of radiology are discussed and the main areas of development over the next few years explored.

Critical threonine and aspartic acid residues within the I domains of beta 2 integrins for interactions with intercellular adhesion molecule 1 (ICAM-1) and C3bi

Integrins mediate signal transduction through interactions with multiple cellular or extracellular matrix ligands. Evidence is accumulating that the I (or A) domain, a approximately 200-residue inserted sequence in some integrin alpha subunits, mediates ligand binding. We have previously shown that Thr-221 of the putative ligand binding sites within alpha 2 I domain of alpha 2 beta 1 is critical for binding to collagen (Kamata, T., and Takada, Y. (1994) J. Biol. Chem. 269, 26006-26010). Here we report that the mutation of Thr-206 of alpha L blocks intercellular adhesion molecule 1 (ICAM-1) binding to alpha L beta 2 and mutation of Thr-209 of alpha M blocks ICAM-1 and C3bi binding to alpha M beta 2. The data indicate the Thr residues of alpha M and alpha L corresponding to Thr-221 of alpha 2 are critically involved in the ligand interaction with beta 2 integrins. The mutations of the Asp-137 and Asp-239 of alpha L also block ICAM-1 binding to alpha L beta 2, as do the corresponding Asp residues of alpha 2 or alpha M in collagen/alpha 2 beta 1 or C3bi/alpha M beta 2 interactions, respectively. These data suggest that these Thr and Asp residues, conserved among I domains, are critical for interaction with structurally distinct ligands (e.g. ICAMs, C3bi, and collagen).

Acetabular fractures: long-term follow-up of open reduction and internal fixation

Eight-seven acetabular fractures in eighty-seven patients underwent open reduction and internal fixation at Vanderbilt University Hospital from 1984 to 1989. Fifty-six were treated by orthopaedic traumatologists. Fifty-six patients returned for long-term follow-up (range 24-80 months, average 43). Harris hip ratings were used to clinically grade the results. Poor results were found in 43%. Eighty-three percent of the patients with poor results had satisfactory surgical reductions with < 3 mm of residual displacement. Factors other than surgical reduction contributed significantly to the poor results. These included hip dislocation associated with the fracture, class III or IV heterotopic ossification, development of avascular necrosis, and age > 40 years. These factors in addition to adequacy of surgical reduction allow us to better counsel patients as to long-term prognosis.

Physician manpower reform: an analysis of the effects of the COGME Fourth Report on internal medicine residency positions. Council on Graduate Medical Education

PURPOSE

To quantitate the impact of the recommendations contained in the Council on Graduate Medical Education (COGME) Fourth Report on the position distribution in internal medicine residency and fellowship programs and to recommend alternative position allocations for discussion.

DATA SOURCES

The COGME Fourth Report, the National Study of Internal Medicine Manpower, and the American Medical Association Annual Survey of Graduate Medical Education.

RESULTS

Our analysis of the COGME Fourth Report indicates that internal medicine PGY-1 positions would decrease from the 8,936 on duty in the 1992 academic year to 6,533 (-26.9%) for the class of the year 2000. Four thousand will enter generalist careers in internal medicine (approximately a 70% increase over current generalist output). The COGME Fourth Report recommendations would allocate first-year fellowship positions for 1,400 graduates of internal medicine residencies (-63.1%). Career-bound internal medicine positions will decrease from approximately 6,000 to 5,400 (-10.0%). The loss in PGY-1 positions is predominantly due to a decrease in the number of preliminary medicine positions and to individuals who switch from career-bound internal medicine positions to other disciplines after the PGY-1 or PGY-2 years. Pediatric positions would increase moderately from 2,426 available in 1993 to 2,520 (+3.9%). Pediatric subspecialty positions would decrease by 25% to 420, with 2,100 residents entering careers in general pediatrics. Family medicine PGY-1 positions would increase from the 2,657 available in 1993 to 3,400 (+28%).

CONCLUSIONS

The recommendations contained in the COGME Fourth Report would substantially reduce the number, and significantly alter the current distribution, of residency positions. The output goals of 50% generalist careers are met by an increase in career-bound generalist positions in all three generalist specialties. The limitation of total positions to the goal of 110% of 1993 U.S. graduates comes predominantly through reduction of specialty/subspecialty career-bound positions. Internal medicine residency and subspecialty fellowship positions and programs would be significantly altered by these recommendations. The reductions in internal medicine occur predominantly in loss of positions not currently destined for careers in internal medicine and in subspecialty fellowship positions. These reductions are partially offset by an increase in the complement of residents who are destined for careers in general internal medicine.

Risk communication: how to answer tough patient questions

Patients are asking: Can I catch AIDS in your office? Should I have my mercury fillings replaced? Are my children in danger from fluoridated water? If X-rays are so safe, why do you leave the room when you take them? Strategies for addressing these and other tough patient questions are discussed.

Compartment syndrome secondary to prolonged intraosseous infusion

Intraosseous infusions are a valuable means of establishing intravascular access in pediatric emergencies. We report a case of compartment syndrome from prolonged intraosseous infusion (53 hours). We postulate that chemical irritation from medications, infections, the tenuous nature of intraosseous infusions, and the use of infusion pumps may all play a role in the development of compartment syndrome. We recommend that, when possible, intraosseous lines be used only temporarily until more permanent vascular access is established, that lines that do not flow with gravity be removed, and that drugs known to cause chemical burns be used with caution. In addition, the use of x-ray and hourly measurement of leg circumference may help to determine whether a line is still in place. Also, given the changing circumstances and technology under which intraosseous infusions are used, new prospective studies of their complications are needed.