Search PubMed⌕ Search

Biomedical subjects

M A Klein

Publications and source records attributed to M A Klein.

78 records · Page 5Linked to original sources
PubMedDate not supplied

MR imaging of the abnormal sternoclavicular joint--a pictorial essay.

The sternoclavicular (SC) joint can be affected by a wide variety of pathologic conditions. Imaging is usually needed for diagnosis and staging. Although the use of magnetic resonance (MR) imaging has become indispensable in the evaluation of most joints, MR has received little attention in SC joint evaluation. Recently, however, it has been shown that detailed MR images of the normal SC joint can be obtained. This pictorial essay explores the differential diagnosis of the abnormal SC joint and helps to determine the role of MR imaging in the SC joint imaging algorithm.

Adult↗
PubMedDate not supplied

Luminal osmolarity downregulates gene expression of Na+/H+ exchanger (NHE3) in rat colon mucosa.

Water-coupled Na&sup+ absorption in the colon is mediated principally by Na+/H+ exchange (isoforms NHE2 and NHE3). To determine whether luminal ion composition or osmolarity influences NHE expression in colon mucosa, two groups (n = 6 in each) of adult male Sprague-Dawley rats underwent sham laparotomy or loop ileostomy. In these studies, diversion did not markedly alter mRNA levels for NHE2, NHE3, or Na+/K+, at 8 or 21 days, indicating that loss of luminal volume does not alter NHE gene expression. To evaluate the effects of specific luminal components, we infused equal volumes of half-normal (154 mOsm) or iso-osmolar (308 mOsm) solutions of saline and mannitol into the diverted colon. All solutions elicited significant (45% to 60%; P <0.05) decreases in mRNA levels for NHE3, with iso-osmolar mannitol eliciting the greatest changes. Decreases in NHE2 and Na+/K+ mRNA levels were observed following these infusions but were not as marked as the changes for NHE3. These findings suggest that (1) loss of luminal Na+ is not, in itself, a signal that regulates NHE expression and (2) infusion of any solute, including Na+ itself, provides a signal to downregulate expression of NHE3 in colon mucosa.

Animals↗
PubMedDate not supplied

Selective decreases in levels of mRNA encoding a water channel (AQP3) in ileal mucosa after ileostomy in the rat.

Water channels (aquaporins) provide pathways for water permeation in a variety of epithelia. Aquaporin-3 (AQP3) has been localized to the basolateral membranes of epithelial cells in the small intestine, but mechanisms that regulate its expression and function have not been explored. To determine whether luminal content may influence intestinal AQP3 gene expression, adult Sprague-Dawley rats underwent sham laparotomy (N = 11) or loop ileostomy (N = 9) and were killed 8 days after procedures. Northern blot analysis was used to measure messenger RNA (mRNA) levels for AQP3 and the Na(+)/K(+) ATPase, a housekeeping transporter that regulates cellular levels of Na(+) and K(+). At sacrifice, histologic examination revealed only minimal changes in mucosal morphology. In sham animals, Na/K mRNA levels increased moderately in distal regions of the small intestine. Ileostomy did not alter these levels in any region. In contrast, in sham animals, AQP3 mRNA levels increased along the length of the intestine and were markedly higher in the distal ileum. Diversion of luminal contents decreased AQP3 mRNA levels in the postileostomy region by 30% to 50%. These findings indicate regional variations in expression of the AQP3 water channel in mucosa of the small intestine. In addition, they suggest that AQP3 gene expression may depend on the presence of luminal contents.

Analysis of Variance↗
PubMedDate not supplied

A crucial role for B cells in neuroinvasive scrapie.

Although prion proteins are most efficiently propagated through intracerebral inoculation, peripheral administration has caused the diseases kuru, iatrogenic Creutzfeldt-Jakob disease (CJD), bovine spongiform encephalopathy (BSE) and new-variant CJD. The development of neurological disease after peripheral inoculation depends on prion expansion within cells of the lymphoreticular system. Here we investigate the identity of these cells by using a panel of immune-deficient mice inoculated with prions intraperitoneally: we found that defects affecting only T lymphocytes had no apparent effect, but that all mutations that disrupted the differentiation and response of B lymphocytes prevented the development of clinical scrapie. As an absence of B cells and of antibodies correlates with severe defects in follicular dendritic cells, a lack of any of these three components may prevent the development of clinical scrapie. However, we found that scrapie developed after peripheral inoculation in mice expressing immunoglobulins that were exclusively of the M subclass and without detectable specificity for the normal form of the prion PrPC, and in mice which had differentiated B cells but no functional follicular dendritic cells. We conclude that differentiated B cells are crucial for neuroinvasion by scrapie, regardless of the specificity of their receptors.

Animals↗
PubMedDate not supplied

MR imaging of septic sacroiliitis.

Septic sacroiliitis is difficult to diagnose, causing delayed treatment and increased morbidity. The traditional imaging techniques for diagnosis have been CT and nuclear medicine. Our purpose was to determine the ability of MR imaging to detect septic sacroiliitis, to evaluate the features of septic sacroiliitis with MR, and to compare the relative detection rate of MR, CT, and nuclear medicine. All patients with a discharge diagnosis of septic sacroiliitis who were evaluated by MR imaging of the pelvis were retrospectively evaluated. Five patients were collected with six septic sacroiliac joints, which were also evaluated with CT, 99mTc-methylene diphosphonate bone scans, and 67Ga-citrate scans. Abnormalities consistent with sacroiliitis were seen in all sacroiliac joints both prospectively (impression from the initial report) and retrospectively on MR. In addition to the nonspecific MR findings of inflammation and/or fluid in the sacroiliac joint space, bone marrow of the sacrum and/or ilium, and iliopsoas muscle, fluid/inflammation was uniquely identified tracking posterior to the iliopsoas muscle in each of these patients with septic sacroiliitis. Even in retrospect, a definite diagnosis of sacroiliitis could be made in only five of six joints by 67Ga-citrate scans, three of six joints by CT scans, and one of six joints by 99mTc-methylene diphosphonate bone scans. These results suggest MR imaging may be a sensitive modality in the early diagnosis of septic sacroiliitis.

Adult↗