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Biomedical subjects

R J Metz

Publications and source records attributed to R J Metz.

18 recordsLinked to original sources

Cervical artery dissection: An atypical presentation with Ehlers-Danlos-like collagen pathology?

The authors took skin biopsies of the macroscopically normal skin of seven consecutive patients with spontaneous cervical artery dissection (SCAD). Histologically, alterations of the collagen and elastic fiber networks were found in six patients. In five, the histologic, immunohistochemical, and ultrastructural changes were similar to those usually found in Ehlers-Danlos syndrome (EDS). This suggests that SCAD is frequently associated with the dermal alterations seen in EDS.

Adult↗

The effects of small-dose ketamine on propofol sedation: respiration, postoperative mood, perception, cognition, and pain.

We compared the effects of coadministration of propofol and small-dose ketamine to propofol alone on respiration during monitored anesthesia care. In addition, mood, perception, and cognition in the recovery room, and pain after discharge were evaluated. In the Propofol group (n = 20), patients received propofol 38 +/- 24 microg x kg(-1) x min(-1). The Coadministration group (n = 19) received propofol 33 +/- 13 microg x kg(-1) x min(-1) and ketamine 3.7 +/- 1.5 microg x kg(-1) x min(-1). Respiration was assessed by using end-expiratory PCO(2) measurements at nasal prongs. After surgeries, mood, perception, and thought were assessed by using visual analog scales, and cognition was assessed by Mini-Mental State Examination (MMSE). Pain after discharge was assessed by a five-point rating scale in the evening for 5 days. End-expiratory PCO(2) was lower in the Coadministration group (P < 0.0001). Mood and MMSE scores were higher in the Coadministration group (P < 0.004 and P = 0.001, respectively). Pain scores and analgesic consumption after discharge were less in the Coadministration group (P = 0.0004 and P < 0.0001, respectively). We conclude that coadministration of small-dose ketamine attenuates propofol-induced hypoventilation, produces positive mood effects without perceptual changes after surgery, and may provide earlier recovery of cognition.

Adult↗

Multiple brain infarcts: clinical and neuroimaging patterns using diffusion-weighted magnetic resonance.

The capability of diffusion-weighted (DW) magnetic resonance imaging (MRI) to identify very early ischemic brain injury better than conventional MRI is well known. This technique, which successfully discriminates acute from old infarcts, is particularly useful in patients with multiple brain infarcts (MBI). Among 142 patients with acute stroke consecutively admitted to our primary care center, we selected 43 patients with two or more brain infarcts on conventional MRI. All patients presented with clinical deficits consistent with acute cerebral ischemia and underwent conventional spin echo for T(1) (T1-WI) and T(2)-weighted images (T2-WI), T(1)-W gadolinium-enhanced images, and echo-planar technique for DW MRI sequences. Patients underwent DW MRI examinations within 15 days of stroke onset (mean +/- SD: 3 +/- 3 days). In all but 1 case, the infarcts detected on DW MRI were also visible on T2-WI. The different signal pattern on DW MRI, compared with T2-WI, facilitated the detection of acute infarcts in all patients. T1-WI with gadolinium enhancement was only helpful in 5 (11.6%) patients. DW MRI enabled precise clinicotopographic correlations in 79% of our patients and provided additional clinically relevant findings in 72% of the patients. Based on the neuroradiological findings, patients were divided into three clinicotopographic types of MBI as follows: 13 patients (30.2%) presented with multiple acute infarcts, 24 patients (55.8%) with a single acute infarct and multiple old infarcts, and 6 patients (13.9%) with multiple acute and old infarcts. In conclusion, DW MRI can easily be added to conventional MRI in order to be able to distinguish acute from old infarcts, and to identify acute multiple lesions. Therefore, a better correlation between clinical symptoms and the site of lesions can be obtained, considerably improving patient care.

Adolescent↗

1alpha,25-dihydroxyvitamin D3 activates T cells of tumor bearers through protein phosphatase 2A.

The sterol 1alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] can inhibit T cell activation as well as restore the functional competence of suppressed T cells, The present studies determined whether 1,25(OH)2D3 had a differential effect on the activation of normal T cells or of suppressed T cells from mice bearing Lewis lung carcinoma tumors. Normal spleen cell proliferation in response to immobilized anti-CD3 was unaffected by the lower doses of 0.1-10 nM 1,25(OH)2D3, and was inhibited by the higher dose of 100 nM 1,25(OH)2D3. In contrast, 1,25(OH)2D3 increased proliferation and interferon gamma secretion by T cells of tumor bearers in response to stimulation through T cell receptor/CD3. Assessment of mechanisms associated with the 1,25(OH)2D3 stimulation of tumor-bearer T cells implicated protein phosphatase 2A (PP-2A). First, PP-2A activity of spleen cells from tumor bearers was reduced compared to that of normal spleen cells but was increased by 1,25(OH)2D3. Second, 1,25(OH)2D3 stimulation of tumor-bearer T cell proliferation was dependent on this PP-2A activity as it was blocked by doses of okadaic acid that selectively inhibit PP-2A. These results suggest that 1,25(OH)2D3 preferentially enhances the responsiveness of immunosuppressed T cells from tumor bearers to TCR/CD3 stimulation by restoring PP-2A activity.

Animals↗

[Lacunar cerebral lesions and vascular risk factors].

Since their detailed description by Fisher, lacunar strokes are known to have particular clinical presentations, etiologies and prognostic implications. Small artery disease is at the origin of most lacunes and was classically believed to be mainly due to hypertension. Recent studies have shown no differences in the prevalence of hypertension in patients with lacunar infarction compared to patients with non-lacunar infarction. Vascular risk factors may be different in single versus multiple lacunes and in the presence or absence of leukoaraiosis. The association of several risk factors in an individual patient probably also is of major importance for the development of small artery disease. Further studies on the risk factors for lacunes should separate single from multiple lacunes and carefully analyze the different patterns of risk association.

Cerebral Infarction↗

Vitamin D3 and ceramide reduce the invasion of tumor cells through extracellular matrix components by elevating protein phosphatase-2A.

Increasing phosphorylation reactions by protein kinase A (PKA) or reducing dephosphorylation reactions of protein phosphatase-2A (PP-2A) increases the invasiveness of Lewis lung carcinoma (LLC) cells, as measured by their capacity to traverse extracellular matrix (ECM)-coated filters. Metastatic LLC-LN7 variants have reduced PP-2A activity when compared to nonmetastatic LLC-C8 variants. Immunoblotting showed that this reduced level of PP-2A activity was not due to reduced levels of the PP-2A catalytic (C) subunit. The cellular PP-2A activity could be stimulated by addition of C2-ceramide to LLC-LN7 lysates, or by incubating cells with either C2-ceramide or with a noncalcemic analog of vitamin D3, which has previously been shown to stimulate the release of ceramide. These treatments to elevate PP-2A activity in metastatic LLC-LN7 cells resulted in a decline in their capacity to invade through select (ECM) components, particularly through vitronectin and laminin. Underscoring the importance of PP-2A in limiting the invasiveness of tumor cells was the demonstration that LLC-LN7 cell transfectants overexpressing the PP-2A C alpha subunit were less invasive through ECM components than the wild-type cells. Invasion by these cells was further reduced by additionally increasing PP-2A activity by incubation with C2-ceramide or the vitamin D3 analog. These results suggest a role of a vitamin D3/ceramide/PP-2A pathway in limiting the invasiveness of tumor cells through select ECM components.

Animals↗

[Oculomotor disorders caused by thalamo-peduncular infarction after vertebral artery dissection].

A case of left vertebral artery dissection after neck manipulation associated with an ipsilateral thalamo-peduncular infarct by distal embolism is reported. The oculomotor signs observed are explained for the left eye by an intra-axial third nerve lesion, and for the right eye by a limitation of the horizontal gaze to the right and an upgaze palsy of supranuclear origin. The association of infra and supranuclear lesions without nuclear lesion in thalamo-peduncular infarcts is considered.

Aortic Dissection↗

Rat hepatic cytosolic phosphoenolpyruvate carboxykinase (GTP). Structures of the protein, messenger RNA, and gene.

The primary structure of the messenger RNA coding for cytosolic phosphoenolpyruvate carboxykinase was determined by sequencing cDNA and genomic DNA and by primer extension of the mRNA. The molecule is 2624 nucleotides in length; this includes 143 nontranslated nucleotides at the 5' end and 615 nontranslated nucleotides at the 3' end. The 3' nontranslated sequence contains a 102-base pair region of alternating purine-pyrimidine nucleotides (the majority of which are UpG dinucleotides), several direct repeats and palindromic sequences, and 8 CpG dinucleotides. The corresponding segment of the phosphoenolpyruvate carboxykinase gene thus has characteristics which favor the formation of Z-DNA. The amino acid sequence of phosphoenolpyruvate carboxykinase was deduced from the mRNA sequence and confirmed by fast atom bombardment mass spectrometric analysis of peptides generated with trypsin and Staphylococcus aureus V8 protease. The protein consists of 621 amino acids and has a molecular weight of 69,289. Charon 4A lambda bacteriophage clones containing genomic DNA coding for phosphoenolpyruvate carboxykinase were isolated from a library of partial HaeIII digests of rat liver DNA. Two clones, lambda PC112 and lambda PC103, contained the entire coding region in 15-kilobase inserts and were used to subclone the gene into pBR322 as EcoRI, BamHI, or SstI-KpnI fragments. Using these subclones, the structure of the phosphoenolpyruvate carboxykinase gene was determined by S1 nuclease mapping, R-loop analysis, and DNA sequencing. The gene is composed of 10 exons and 9 introns with a total length of 6.0 kilobases. The transcription initiation site of the gene was determined by a combination of in vitro transcription in a HeLa cell lysate system, primer extension of mRNAPEPCK, and S1 nuclease mapping. In vitro transcription of purified DNA templates revealed three RNA polymerase II-dependent start sites. Two sites were separated by 600 base pairs on the coding strand and the third site was on the noncoding strand. The products of S1 nuclease mapping and primer extension from a BglII site were compared in order to determine which of the coding strand initiation sites was expressed in vivo. In both cases a 69-base pair fragment was generated and the 5' end of this corresponded to a thymidine residue identified in a sequence ladder of the genomic DNA coding strand. We conclude that mRNAPEPCK synthesis initiates with an adenine residue 69 base pairs 5' of the BglII site; this corresponds to the 3' most transcription initiation site determined in vitro.

Amino Acid Sequence↗

Long-term metabolic control with insulin pump therapy. Report of experience with 127 patients.

To determine the long-term efficacy of insulin-pump therapy, we analyzed trends in glycosylated hemoglobin concentrations in 127 patients with Type I diabetes using insulin pumps for periods ranging from 13 to 47 months. In the first year of pump therapy the average glycosylated hemoglobin concentration improved in 83 per cent of the patients, as compared with the value before pump therapy. Although only 11 of the 127 subjects had normal glycosylated hemoglobin values before pump therapy, 33 had a normal average value during the first full year of pump use (P = 0.0001). This favorable trend persisted for the three-year duration of the study. Seventeen of the 19 patients who subsequently discontinued insulin-pump therapy had improved glycosylated hemoglobin values during the period of pump use. Eleven of the 19 patients remained available for follow-up study; the glycosylated hemoglobin concentration became worse in 7 when they returned to conventional treatment. We conclude that the improvement in metabolic control repeatedly demonstrated in short-term studies with the insulin pump can be maintained for a period of years.

Adult↗

Acute complications associated with insulin infusion pump therapy. Report of experience with 161 patients.

We determined the frequency of acute complications associated with insulin pump therapy in 161 insulin-dependent patients followed up for a total of 2,978 patient-months. Diabetes control improved substantively with pump therapy, but 42% of the patients experienced one or more acute complications while using insulin pumps. Infected infusion sites, ketoacidosis, and hypoglycemic coma occurred once in every 27, 78, and 175 patient-months, respectively. More patients experienced ketoacidosis after the onset of pump therapy than in an equivalent interval immediately before the onset of pump therapy. Ketoacidosis also occurred in more patients using pump therapy than in a comparison group of 165 patients receiving conventional insulin injections surveyed during an equivalent period. The frequency of hypoglycemic coma was not significantly changed by pump therapy.

Acute Disease↗

Clinical use of the insulin infusion pump in 100 patients with type I diabetes.

We investigated the efficacy of insulin-pump therapy in insulin-dependent diabetics, aged 18 to 69 years, by comparing the metabolic control achieved in 100 patients using this technique with that previously obtained by conventional insulin therapy. Patients were followed during pump therapy for as long as 15 months. Fasting and nonfasting blood glucose levels (mean +/- S.E.M.) decreased from 201 +/- 6 and 213 +/- 6 mg per deciliter (11.2 +/- 0.3 and 11.8 +/- 0.3 mmol per liter), respectively, to 158 +/- 5 and 145 +/- 3 mg per deciliter (8.77 +/- 0.3 and 8.05 +/- 0.2 mmol per liter) after one month of pump therapy (P less than 0.001). Ninety-three patients had improved blood sugar control; 71 per cent had a mean blood sugar concentration of 150 mg per deciliter (8.3 mmol per liter) or less after six months. Glycosylated hemoglobin values became normal in 44 per cent of 88 patients who had follow-up determinations. In over 500 patient-months there were four episodes of ketoacidosis and five episodes of serious hypoglycemia. Three patients abandoned pump therapy. We conclude that insulin-pump therapy is acceptable to patients and that it can be successfully applied to clinical practice and large-scale research studies.

Adolescent↗

Glucosylceramide uptake protein from spleen cytosol.

Incubation of rat red cells with liposomes containing radioactive glucosylceramide, together with unlabeled phosphatidylcholine and cholesterol, produced cells labeled with the glycolipid. Part of the bound cerebroside could be removed by further incubation with unlabeled liposomes. Both processes, uptake and release, were stimulated by adding a preparation obtained from bovine spleen. The active material was purified partially by ammonium sulfate precipitation and gel permeation with a Sephadex G-75 column. The latter step indicated a molecular weight of about 22,000. The material lost much of its activity when treated with trypsin or N-ethylmaleimide, indicating that it is a protein. The "cerebroside uptake protein" was quite stable if stored in dithioerythritol at 4 degrees C. Tests with liposomes containing labeled phosphatidylcholine or cholesterol showed that the red cells took up these lipids as well, but the transfer protein exerted little effect on this. Ghosts prepared from rat red cells also took up the three lipids from the liposomes and here, as well, the uptake protein showed high specificity in facilitating the uptake of cerebroside. This appears to be the first demonstration of the existence of a glycolipid transfer protein. Possible physiological roles for the uptake protein in red cell metabolism and in the modulation of the glycosphingolipid composition of cell membranes are discussed.

Animals↗

The hepatorenal syndrome.

The hepatorenal syndrome is defined as the spontaneous onset of progressive renal failure in patients with far advanced hepatic disease, usually on the basis of cirrhosis. The clinical characteristics of the syndrome include azotemia, oliguria, hyponatremia, low urinary sodium excretion and the absence of abnormal findings in the urinary sediment. Although the results of a large number of studies suggest that abnormal histologic features in the kidneys are infrequent, changes such as glomerulosclerosis, degeneration of tubular cells and alterations in the basement membranes have been described. Theories on the pathophysiologic aspects of the syndrome, including reduced plasma volume, inferior vena cava hypertension and active renal vasoconstriction, are presented. The last of these is currently the most widely accepted theory in which there is a selective redistribution of blood flow away from the cortical nephrons to the medullary nephrons on the basis of selective cortical vasoconstriction. The role of the synpathetic nervous system, as well as that of plasma renins in the cause of this condition is explored. Therapy for the hepatorenal syndrome generally has failed to ameliorate extremely unfavorable mortality rates. Such factors as the effects of plasma volume expansion; various pharmacologic agents, including dopamine, Octopressin and metaraminol; portacaval shunt; transplantation of the liver, and steroids are discussed. Regardless of specific therapy, the few patients who do survive tend to demonstrate a significant reversible component with respect to hepatic disease.

Diagnosis, Differential↗