Search PubMed⌕ Search

Biomedical subjects

F Long

Publications and source records attributed to F Long.

At least 37 records · Page 2Linked to original sources
PubMed1997

Proviral organization and sequence analysis of feline immunodeficiency virus isolated from a Pallas' cat.

The nucleotide sequence and genomic organization have been determined for a highly cytopathic feline immunodeficiency virus (FIV) isolated from a Pallas' cat. The 9747-bp provirus of this virus, FIV-Oma, has typical lentivirus organization with LTRs, gag, pol, and env open reading frames (ORFs), putative vif and rev ORFs, and an ORF similar to ORF2/ORFA of domestic cat FIV isolates. Although the FIV-Oma provirus is 300 to 600 bp longer than other FIV proviruses, these additional bases are distributed throughout the genome. Phylogenetic analysis of a conserved region of the pol gene suggests that FIV-Oma is more closely related to some of the puma and lion lentiviruses than it is to domestic cat FIV isolates; however, many regions of the genome exhibit extensive nucleotide sequence divergence. None of the eight molecular proviral clones isolated from a genomic library are infectious, but we have constructed an infectious, cytopathic clone of FIV-Oma from subcloned and PCR-amplified fragments of these proviral clones. This clone will be useful for identifying the genetic determinants of FIV-Oma's biological activities.

Amino Acid Sequence↗
PubMed1997

Fast gradient echo MR imaging of the liver enhanced with superparamagnetic iron oxide.

The purpose of this study was to develop a breath-hold technique for hepatic imaging using SPIO-enhanced gradient echo. Pre- and post-SPIO driven equilibrium fast gradient echo scans were performed on five healthy subjects. Scan parameters were established to emphasize large pre-/post-signal differences while maintaining a scan time conducive to breath-hold. Hepatic post-SPIO signal reduction was at least fifty percent with diagnostic image quality in all subjects. SPIO-enhanced gradient echo provides slightly less hepatic signal reduction to spin echo techniques but can be performed within a single breath-hold. This technique may be advantageous over SE in assessing hepatic pathology in subjects unable to lay motionless for prolonged intervals, such as children.

Adult↗
PubMed1996

Tyrosine-272 is involved in the inhibition of protein phosphatase-1 by multiple toxins.

Protein phosphatase-1 (PP1) is regulated by interaction with different subunits, which include several inhibitory proteins. It is also potently inhibited by several toxins of diverse origins. Recent work has identified a region near the C-terminus of PP1 (residues 274-277) whose modification was shown to moderate okadaic acid binding [Zhang et al. (1994) J. Biol. Chem. 269, 16997-17000]. In this study, the role of this region in toxin binding was explored by site-directed mutagenesis. A residue (Tyr-272) was identified whose mutation had dramatic effects on the spectrum of inhibitor sensitivity of PP1. The IC50's of a number of mutants of Tyr-272 toward okadaic acid, tautomycin, calyculin A, microcystin-LR, nodularin, inhibitor-2, and cantharidic acid were determined and compared to that of the wild-type enzyme. The sensitivity of PP1 toward tautomycin and calyculin A was markedly decreased, by as much as 3 orders of magnitude, with lesser effects on okadaic acid and nodularin, and with microcystin-LR and inhibitor-2 being the least affected. These studies show that Tyr-272 is of specific importance for the binding of these inhibitors and provide strong evidence for the postulate that these toxins all bind to a common inhibitor site on PP1. In addition, our studies show that Tyr-272 is not required for catalytic activity.

Amino Acid Sequence↗
PubMed1995

Tissue-specific regulation of the type X collagen gene. Analyses by in vivo footprinting and transfection with a proximal promoter region.

During endochondral bone formation, hypertrophic chondrocytes initiate synthesis of type X collagen. Previous studies have shown that regulation of this molecule is at the level of transcription. To further explore this regulation, we have studied a segment of the type X collagen gene extending from 562 base pairs (bp) upstream to 86 bp downstream of the transcriptional start site. We have studied this "proximal promoter region" by both structural analysis by DNase I in vivo footprinting and functional analysis by transient transfections. In type X collagen-expressing, hypertrophic chondrocytes, in vivo footprinting detected a fully protected TATA region flanked by hypersensitive sites but no other major protection. Type X collagen-negative cells (nonhypertrophic chondrocytes and tendon fibroblasts) showed major protection at a number of other sites, most notably an 8-bp region overlapping an AP2 site and a 9-bp region including the sequence CACACA. The importance of the proximal promoter region in restricting expression of type X collagen to hypertrophic chondrocytes was supported by transfection studies. A chloramphenicol acetyltransferase construct containing this region directed 5-10-fold higher chloramphenicol acetyltransferase expression in hypertrophic chondrocytes than in the other cell types. A 2.6-kilobase upstream fragment produced no additional effect. Thus, the proximal promoter region contains at least some regulatory elements for the cell-specific expression of type X collagen.

Animals↗
PubMed1995

Clinical stage I endometrial carcinoma: pitfalls in preoperative assessment with MR imaging. Work in progress.

PURPOSE: To identify potential pitfalls in using magnetic resonance (MR) imaging to determine the depth of myometrial invasion in patients with clinical stage I endometrial carcinoma. MATERIALS AND METHODS: Forty women with clinical stage I endometrial carcinoma underwent preoperative pelvic MR imaging. Uterine length, tumor signal intensity, appearance of the junctional zone, presence of large polypoid tumors, leiomyomata, and congenital uterine anomalies were analyzed. Univariate logistic-regression analysis was performed to identify associations between incorrect MR staging and these variables. RESULTS: MR staging of IA, IB, and IC disease was 55% accurate (22 of 40 cases); MR differentiation of deep myometrial invasion (stage IC) from superficial disease (stages IA and IB) was 78% accurate (31 of 40 cases). Older age (P = .025), presence of polypoid tumors (P = .025), and difficulty in pathologic staging (P < .005) were significantly associated with incorrect MR assessment. CONCLUSION: When present, large polypoid tumors, leiomyomata, congenital anomalies, small uteri, and indistinct zonal anatomy may make it difficult to assess myometrial invasion at MR imaging.

Aged↗
PubMed1994

A mutant of protein phosphatase-1 that exhibits altered toxin sensitivity.

A chimeric mutant was constructed in which a 4-amino acid region (GEFD, residues 274-277) of rabbit muscle protein phosphatase-1 was replaced with the sequence YRCG corresponding to residues 267-270 of rabbit protein phosphatase-2A. This was based on the findings of a gene mutation in okadaic acid-resistant cells which results in a Cys-->Gly conversion in protein phosphatase-2A. The YRCG mutant of protein phosphatase-1 was expressed and purified. The properties of the mutant enzyme were investigated in terms of its sensitivity toward several toxin inhibitors (okadaic acid, microcystin, nodularin, calyculin A, and cantharidic acid), as well as inhibitor-2. The mutant enzyme exhibited a gain of function in the form of a 10-fold increased sensitivity toward okadaic acid that suggests this region is involved in toxin binding. Significant changes in sensitivity to inhibitor-2 and several of the other toxins were also observed, indicating that these may have a common binding region.

Amino Acid Sequence↗
PubMed1994

A new proline-rich early nodulin from Medicago truncatula is highly expressed in nodule meristematic cells.

We cloned and characterized MtPRP4, a new member of the repetitive proline-rich protein gene family in Medicago truncatula. The sequence of MtPRP4 predicts a 62-kD protein consisting of a 22-amino acid N-terminal signal peptide and a 527-amino acid repetitive proline-rich domain composed of three repetitive pentapeptide motifs arranged into two decapeptide repeats: PPVEKPPVHK and PPVEKPPVYK. MtPRP4 is the largest PRP described to date and contains repeated motifs that have not previously been found together in a single polypeptide. RNA gel blot experiments detected MtPRP4 transcripts in symbiotic root nodules, but not in roots, hypocotyls, or leaves. Accumulation of MtPRP4 transcript was an early response to Rhizobium inoculation and did not depend on nodule infection. In situ hybridization experiments demonstrated that MtPRP4 was expressed early in the development of the nodule meristem and that expression was highest in the meristematic cells of mature indeterminate nodules. These data support the proposition that an important early response of legume host roots to Rhizobium involves remodeling the host extracellular matrix and that proline-rich wall proteins play an important role in this architectural modification.

Amino Acid Sequence↗
PubMed1991

Designing appropriate nutrition education for the Chinese: the urban and rural nutrition situation in Sichuan.

In the People's Republic of China, as in the West, diet has emerged as an important determinant of morbidity and mortality. In order to provide one of the bases for designing nutrition education, two nutrition knowledge-attitudes-practices surveys of adults aged 18-55 were conducted in 1989 in an urban (N = 1004) and a rural (N = 506) area of Sichuan. Nutrition knowledge levels were low in both sites, but lower in the rural site. Certain general nutrition concepts, such as the value of a varied diet, were reported correctly by over 50 per cent of the population in both areas. However, less than 10 per cent of the urban residents and only 3 per cent of the rural residents reported taking correct measures to prevent or delay cancer or heart disease. Dietary practices, elicited by a food frequency questionnaire, revealed large differences in consumption habits in the two areas. More than half of the urban respondents reported eating rice, vegetable oil, green vegetables, lean meat, and wheat on a daily basis, and other vegetables, pickles, fruit, eggs, soybean products, and meat fat on at least a weekly basis. However, the rural respondents reported eating only rice, vegetable oil, green vegetables, and other vegetables on a daily basis, and no additional foods on a weekly basis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

A rare cause of intra-abdominal hemorrhage. Leiomyoma of the small bowel.

As a result of infrequent occurrence, small bowel tumors of the intestine offer a diagnostic challenge. A spectrum of presentations are possible, ranging from vague abdominal symptoms to life-threatening intra-abdominal hemorrhage. Contrast radiographs are helpful in diagnosis but additional studies may be necessary. Treatment is usually simple excision. The prognosis of benign tumors is excellent. Because of the non-specificity of signs and symptoms of small bowel tumors, a high index of suspicion is required, especially since these lesions themselves can be dangerous and often occur in the age group for intra-abdominal malignancy.

Adult↗
PubMed1988

[Growth capability of epithelial cell line of human poorly differentiated nasopharyngeal carcinoma and its response to Chinese medicinal herbs and marine drugs].

By 3H-TdR incorporation, dye exclusion and cell colony-forming tests, the capability of short-term in vitro growth of the epithelial cell line of human poorly differentiated nasopharyngeal carcinoma (CNE-2Z) was assayed. At the same time, its response to 54 kinds of Chinese medicinal herbs and marine drugs was studied. The results showed that the 3H-TdR incorporation rate of cells was 1.8 +/- 0.02%, reproduction rate was 60.9 +/- 13.0% and colony-forming rate, 40.8 +/- 3.5%. As to the ratios of the three cell growth indexes and response to medicines, the Chinese medicinal herbs and marine drugs causing the reduction of colony-forming and cell survival ratios were predominant (64.8% and 40.7%). The results indicate that the majority of drugs possess the cytotoxic and inhibitory effect on cell reproduction to different degrees. The composite cell response to every kind of drug could be divided into 6 types: descending, ascending, peaked, valley-like, depressed and stable. The depressing type drugs might inhibit or arrest the cell growth of nasopharyngeal carcinoma and are worthy of further study.

Cell Division↗
PubMed1987

Effect of oral frusemide on diagnostic indices of thyroid function.

We studied the acute effect of standard therapeutic doses of oral frusemide on indices of thyroid function in 34 hospital in-patients with congestive cardiac failure. A transient decrease in total T4, elevation in the T3 resin uptake and consequent increase in the free T4 index (FT4I) were seen 2-5 h after ingestion of frusemide at a chronic morning dosage of 80, 120 or 250 mg. The FT4I pre-vs post-frusemide values after 250 mg of drug were 109 +/- 12 vs 129 +/- 18 (P less than 0.05) after 120 mg 92 +/- 14 vs 119 +/- 12 (P less than 0.01), and after 80 mg 102 +/- 6 vs 112 +/- 4 (P less than 0.01) (mean +/- SEM). Similar increases in apparent free T4 measured by an analogue tracer assay (free T4 RIA sol, Henning, Berlin) were seen after frusemide. In a time course study, the major change in the T3 uptake 120 min after frusemide ingestion correlated with the change in serum frusemide concentration. When frusemide was added to serum in vitro its influence was greatest in methods that involved least dilution of serum. In two of the patients difficulty in clinical assessment of thyroid status was compounded by the effect of oral frusemide on FT4I. We conclude that oral frusemide may influence biochemical assessments of thyroid function in patients with congestive cardiac failure. It is necessary to consider the time interval between ingestion of high doses of oral frusemide and blood sampling in evaluating such results.

Administration, Oral↗
PubMed1981

Absorbable suture materials for vascular anastomoses. Tensile strength and axial pressure studies using polyglycolic acid sutures.

This study attempted to evaluate how vascular healing itself is sufficient enough to provide adequate strength to autogenous vein grafts in small arteries without the use of nonabsorbable sutures. The absorbable suture, Dexon, was used in small canine femoral vein graft anastomoses over a two-month trial period with nonabsorbable Prolene as a control. Tensile strength and resistance to axial leak were measured. Results show that Dexon had 93 per cent of the tensile strength of Prolene immediately; 76 per cent at 14 days, 111 per cent at 21 days, and 110 per cent at 30 days, and 124 per cent at 60 days as an average for all suture lines. The per cent mean resistance to leakage that Dexon had compared to Prolene for all suture lines was 102 per cent at seven days, 97 per cent at 14 days, 107 per cent at 21 days, and 97 per cent at 30 days. There is no evidence of aneurysms, suture line disruptions, dilations, or infections of any anastomoses. Our ultimate conclusion is that the integrity of small autogenous vein graft is dependent on healing rather than on the permanent strength of the suture material and that Dexon maintains vascular integrity long enough to permit this healing to occur.

Absorption↗
PubMed1979

Abortion.

Explore the source record for details and available documents.

Abortion, Legal↗
PubMedDate not supplied

Post-partum hypercalcemia in hereditary hyperphosphatasia (juvenile Paget's disease).

Hereditary hyperphosphatasia is a rare bone disorder characterized by increased bone turnover, elevated alkaline phosphatase (ALP) and bone deformity. We describe a patient with a mild form of hereditary hyperphosphatasia who was initially hypercalcemic in childhood with remission after puberty. Symptomatic hypercalcemia recurred during lactation after each of two pregnancies, associated with increased bone turnover (rise in ALP, osteocalcin, and urine hydroxyproline excretion) which appeared to be independent of changes in major calcium-regulating hormones. The mechanism for the development of post-partum hypercalcemia remains unclear but may relate to the relative estrogen deficiency of lactation. We postulate that acute estrogen withdrawal may result in hypercalcemia in the presence of markedly increased bone turnover.

Adult↗