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J Palmer

Publications and source records attributed to J Palmer.

At least 307 records · Page 17Linked to original sources
PubMed1967

Involvement of the lac regulatory genes in catabolite repression in Escherichia coli.

1. Acute transient catabolite repression of beta-galactosidase synthesis, observed when glucose is added to glycerol-grown cells of Escherichia coli (Moses & Prevost, 1966), requires the presence of a functional operator gene (o) in the lactose operon. Total deletion of the operator gene abolished acute transient repression, even in the presence of a functional regulator gene (i). 2. Regulator constitutives (i(-)) also show transient repression provided that the operator gene is functional. Regulator deletion mutants (i(del)), with which to test specifically the role of the i gene, have not so far been available. 3. The above mutants, showing various changes in the lactose operon, show no alteration in the effect of glucose on induced tryptophanase synthesis. Glucose metabolism, as measured in terms of the release of (14)CO(2) from [1-(14)C]glucose and [6-(14)C]glucose, also showed no differences between strains exhibiting or not exhibiting transient repression. This suggests no change in the operation of the pentose phosphate cycle, a metabolic activity known to be of paramount importance for glucose repression of beta-galactosidase synthesis (Prevost & Moses, 1967). 4. Chronic permanent repression by glucose of beta-galactosidase synthesis (less severe in degree than acute transient repression) persists in strains in which transient repression has been genetically abolished. Constitutive alkaline-phosphatase synthesis, which shows no transient repression, also demonstrates chronic permanent repression by glucose. 5. Chloramphenicol repression also persists in mutants with no transient repression, and also affects alkaline phosphatase. It is suggested that chronic permanent repression and chloramphenicol repression are non-specific, and that they do not influence beta-galactosidase synthesis via the regulatory system of the lactose operon.

Alkaline Phosphatase↗
PubMedDate not supplied

AIDS-related primary esophageal lymphoma.

AIDS-related primary esophageal lymphoma should be considered in the differential diagnosis of a patient with AIDS who presents with dysphagia and a large ulcerated esophageal mass. Endoscopy is mandatory in those patients to establish a definitive diagnosis and to rule out the possibility of an infectious cause of the mass.

Adult↗
PubMedDate not supplied

Mycotic aneurysm of the abdominal aorta: CT finding in three patients.

We present three cases of mycotic aneurysms of the abdominal aorta that were initially diagnosed with computed tomography (CT). The accuracy of CT as the first imaging technique in the diagnosis of this condition is reviewed in light of our results and those reported in the literature.

Aged↗
PubMedDate not supplied

Acute pancreatitis: value of CT as a predictor of outcome.

A prospective study was performed on the relationship of CT findings to the clinical course of 148 patients with acute pancreatitis. The type of pancreatic inflammation seen on CT was classified into six categories based on an overall assessment of size, contour and density of the gland, and peripancreatic abnormalities. The majority (94%) of patients in whom CT showed mild pancreatic changes (grades A, B and C) had two or less positive clinical indicaters of severe pancreatitis (Ranson's signs). In contrast, 92% of patients in whom CT showed more severe changes of pancreatitis (grades D, E or F) had three or more positive signs. The nine patients who died with pancreatitis-related complications were in grades D, E or F. We wish to draw attention to a CT appearance which we have called 'fat islets' (low density intrapancreatic or peripancreatic areas, the contents of which approach fat in attenuation values); there was a strong correlation between this appearance and subsequent infection.

Acute Disease↗
PubMedDate not supplied

Clinical implication of down-scatter in attenuation-corrected myocardial SPECT.

BACKGROUND: Interpretation of myocardial perfusion single photon emission computed tomography (SPECT) studies is hampered by attenuation artifacts. Attenuation correction methods with simultaneous emission and transmission are now commercially available. However, it has been observed in clinical practice that attenuation correction without down-scatter correction in a 1-day rest/stress myocardial perfusion protocol may lead to serious interpretation errors. Therefore the aim of this study was to study errors resulting from down-scatter under realistic conditions, thus providing a background for the assessment of further corrections. METHODS AND RESULTS: Forty-six patients underwent myocardial perfusion scintigraphy in a 1-day technetium 99m-tetrofosmin rest-stress SPECT protocol, with a moving 153Gd line-source device for attenuation correction without down-scatter correction. Short-axis slices were quantified as inferior/anterior, septal/lateral, and apical/remainder count ratios. The changes at rest (350 MBq) and exercise (900 MBq) induced by attenuation correction were studied. Attenuation correction gave differences in apparent perfusion between rest and exercise not seen before correction. The gender differences in inferior-anterior ratio were greatly reduced after correction at rest but remained at exercise. A torso phantom study indicated that these results were due to under-correction at exercise because of down-scatter. CONCLUSIONS: Down-scatter results in an underestimation of attenuation in simultaneous emission and transmission, if not accurately accounted for. Particularly, a high-dose study compared with a low-dose study, as in the 1-day protocol, might cause serious interpretation errors.

Artifacts↗
PubMedDate not supplied

Efficacy of topical acyclovir monophosphate, acyclovir, or penciclovir in orofacial HSV-1 infections of mice and genital HSV-2 infections of guinea pigs.

The purpose of these studies was to compare the efficacy of acyclovir monophosphate (ACVMP), acyclovir (ACV), or penciclovir (PCV) against HSV-1 in an orofacial infection of mice and against ACV sensitive and resistant genital HSV-2 infections of guinea pigs. Treatment was initiated 24, 48, or 72 hours post inoculation with 5% ACVMP, 5% ACV (Zovirax) or 1% PCV (Denavir). In all experiments, similar efficacy was obtained for ACVMP and ACV, whereas PCV was considerably less effective.

Acyclovir↗
PubMedDate not supplied

Abdominal compartment syndrome in patients with burns.

Abdominal compartment syndrome (ACS) is a well-recognized perioperative complication that occurs in patients who undergo intra-abdominal operations and who require extensive fluid resuscitation. The classic presentation of this syndrome includes high peak airway pressures; oliguria, despite adequate filling pressures; and intra-abdominal pressures of more than 25 mm Hg. A decompressive laparotomy performed at the bedside can alleviate ACS. If left untreated, sustained intra-abdominal hypertension is often fatal. In the literature, ACS has been described in pediatric patients with burns but not in adult patients with burns. This article describes 3 adults who sustained burns of more than 70% of their body surface areas, who required more than 20 L of crystalloid resuscitation, and who developed ACS during their resuscitation after the burn injury. The mortality rate among these patients was 100%, which confirms the grave consequences of this syndrome. In our institution, intra-abdominal pressure is now routinely measured as part of the burn resuscitation process in an attempt to diagnose and treat this syndrome earlier and more efficaciously. It is recommended that the possibility of ACS be considered when diagnosing any patient with burns who develops high airway pressures, oliguria, or both.

Abdomen↗
PubMedDate not supplied

Diverse serologic response to rotavirus infection of infants in a single epidemic.

Eight infants with onset of gastroenteritis occurring within a 32-day period were examined for stool rotavirus antigen and serum antibody response to rotavirus. Each infant presented evidence of rotavirus infection but no single test for rotavirus-specific antigen or antibody was positive for every infected individual. Rotavirus was identified in the stools of five infants; in the others rotavirus etiology was determined by a specific immune response only. The neutralizing antibody response to each of four human rotavirus serotypes and to bovine rotavirus Nebraska calf diarrhea virus ranged from totally negative to a specific response to up to four serotypes. Three originally seropositive infants each showed an increase in neutralizing antibody titer to two or more serotypes. However, two of five originally seronegative infants also developed antibody to two or more serotypes. No consistent pattern of responses to different serotypes was detected.

Antibodies, Viral↗
PubMedDate not supplied

The normal and pathologic ischiorectal fossa at CT and MR imaging.

A wide spectrum of disease processes involve the ischiorectal fossa, including congenital and developmental lesions; inflammatory, traumatic, and hemorrhagic conditions; primary tumors; and pathologic processes outside the ischiorectal fossa with secondary involvement. Both computed tomography (CT) and magnetic resonance (MR) imaging are useful in the definitive diagnosis of these pathologic conditions, with MR imaging being the modality of choice because of its superior contrast resolution and multiplanar capability. In Gartner duct cyst, both CT and MR imaging demonstrate a well-defined, round mass; in tailgut cyst, CT demonstrates a well-defined retrorectal mass with a solid or cystic appearance. MR imaging in particular plays a major role in the assessment of fistula in ano, infection, and hematoma. Lipoma and pelvic plexiform neurofibroma typically have low attenuation and high signal intensity at CT and MR imaging, respectively. Recurrent rectal tumor appears at both modalities as an irregular soft-tissue mass with or without central necrosis in the presacral space, perineum, or pelvic sidewall. Familiarity with the imaging features and differential diagnoses of various ischiorectal pathologic processes will facilitate prompt, accurate diagnosis and treatment.

Adult↗
PubMedDate not supplied

MR imaging of benign soft-tissue masses of the foot and ankle.

Approximately 75% of all biopsy-proved soft-tissue masses of the foot and ankle are benign tumors or nontumoral lesions representing a variety of histologic types. In some cases, it may be difficult if not impossible to identify the lesion; however, careful analysis of the magnetic resonance (MR) imaging findings and correlation of these findings with the patient's clinical history can usually suggest a more specific diagnosis, particularly in the most common benign tumors of the foot (e.g., fibromatosis, cavernous hemangioma) and in nonneoplastic soft-tissue lesions such as Morton neuroma, ganglion cyst, and plantar fasciitis. In addition, a specific diagnosis can almost always be made in patients with pigmented villonodular synovitis (PVNS) or giant cell tumor (GCT) of the tendon sheath. The MR imaging appearance of PVNS consists of multiple synovial lesions with low or intermediate signal intensity on T1-weighted images and low signal intensity on T2-weighted and gradient-echo images. GCTs of the tendon sheath usually have areas of low signal intensity on both T1- and T2-weighted images due to the paramagnetic effect of hemosiderin. Awareness and understanding of the underlying pathologic findings in lesions of the foot and ankle aid in MR imaging interpretation.

Ankle↗