Biomedical subjects

J A Ramsay

Publications and source records attributed to J A Ramsay.

At least 19 recordsLinked to original sources

PubMed2005

Decoloration of textile dyes by alginate-immobilized Trametes versicolor.

Alginate-immobilized Trametes versicolor decolorized Amaranth at similar rates in repeated batch culture when the dye was present in either (i) modified Kirk's medium containing 0.22 gl(-1) ammonium tartrate, (ii) the same buffer, thiamine, trace elements and glucose concentrations as in the modified Kirk's medium, or (iii) glucose alone at either 1, 5 or 10 gl(-1). With glucose alone (0.5 gl(-1)), Amaranth, Reactive Black 5, Reactive Blue 19 and Direct Black 22 had first-order decoloration rate constants of 0.56, 0.76, 0.52, and 0.15 h(-1), respectively. Mixtures of these dyes were also completely decolorized. After four successive decolorations, beads were kept in storage solutions for 48 d at 6 degrees C. CaCl2 (1g l(-1)) was the best storage solution as the beads were easier to handle and had the fastest decoloration rates after storage. Decoloration rates were faster with lower viscosity (less than 2000 cps) alginates and with softer beads which had a lower resistance to compression. Fungal colonization of the beads resulted in higher biomass concentrations with a corresponding higher decoloration rate but the beads became larger, had a lower resistance to compression and a higher percentage of bead breakage in a stirred tank reactor. Biomass, recovered from beads in which there was no growth, could be dispersed while the biomass from colonized beads formed a hollow, spherical shell due to growth on and near the bead surface and no growth in the bead interior. If alginate-immobilized T. versicolor is to be used in a stirred tank reactor, a high biomass loading during the immobilization phase and no fungal growth in the beads is recommended to have high decoloration rates and low bead breakage.

Alginates↗

PubMed2003

Nitrilotriacetate stimulation of anaerobic Fe(III) respiration by mobilization of humic materials in soil.

An enrichment culture capable of naphthalene mineralization reduced Fe(III) oxides without direct contact in anaerobic soil microcosms when the Fe(III) was placed in dialysis membranes or entrapped within alginate beads. Both techniques demonstrated that a component in soil, possibly humic materials, facilitated Fe(III) reduction when direct contact between cells and Fe(III) was not possible. The addition of the synthetic Fe(III) chelator, nitrilotriacetic acid (NTA), to soil enhanced Fe(III) reduction across the dialysis membrane and alginate beads, with the medium changing from clear to a dark brown color. An NTA-soil extract was more effective in Fe(III) reduction than the extracted soil itself. Characteristics of the NTA extract were consistent with that of humic substances. The results indicate that NTA improved Fe(III) reduction not by Fe(III) solubilization but by extraction of humic substances from soil into the aqueous medium. This is the first study in which stimulation of Fe(III) reduction through the addition of chemical chelators is shown to be due to the extraction of electron-shuttling compounds from the soil and not to solubilization of the Fe(III) and indicates that mobilization of humic materials could be an important component of anaerobic biostimulation.

Anaerobiosis↗

PubMed2000

Holoprosencephaly, sacral anomalies, and situs ambiguus in an infant with partial monosomy 7q/trisomy 2p and SHH and HLXB9 haploinsufficiency..

We report an infant with holoprosencephaly (HPE), sacral anomalies, and situs ambiguus with a 46,XY,der(7)t(2;7)(p23.2;q36.1) karyotype as a result of an adjacent-1 segregation of a t(2;7)pat. The chromosomal abnormality was diagnosed prenatally after sonographic detection of HPE in the fetus. The baby was born at 37 weeks gestation, and died in the newborn period; he had dysmorphic features consistent with HPE sequence. Postmortem internal evaluation showed semilobar HPE, abdominal situs ambiguus, multiple segments of bowel atresia, dilatation of the ureters, and bony sacral anomalies. Molecular analysis confirmed hemizygosity for the SHH and HLXB9 genes, which are likely to be responsible for the HPE and sacral phenotypes, respectively. Immunohistochemical studies showed intact dopaminergic pathways in the mesencephalon, suggesting that midbrain dopamine neuron induction appears to require only one functioning SHH allele.

Abdomen↗

PubMed2000

Recurrent familial neonatal deaths: hereditary surfactant protein B deficiency.

Hereditary surfactant protein B (SP-B) deficiency is an uncommon autosomal recessive lung disorder that causes hypoxemic respiratory failure in mature, morphologically normal infants. Recognition and diagnosis of this condition is of paramount importance, as it has significant implications for future pregnancies with a recurrence risk of 25%. In a family with three neonatal deaths over 20 years, SP-B deficiency was diagnosed following the death of the fourth affected infant. Previous deaths were mistakenly attributed to hyaline membrane disease (HMD), congenital Mycoplasma hominis infection, and pulmonary hypertension, however, following the diagnosis in the proposita, SP-B deficiency was also confirmed in her deceased siblings by immunohistochemical staining of autopsy specimens. This case highlights the presentation, postnatal course, diagnosis, and therapeutic options of SP-B deficiency in addition to the mode of inheritance and the possibility of antenatal diagnosis. Genetic consultation is imperative in the investigations of recurrent neonatal deaths, especially in cases of remote events. The recent enormous advances in human genetics have shown that many conditions previously ascribed to environmental agents have a genetic basis.

Fatal Outcome↗

PubMed1998

Multiple congenital anomalies in a fetus with 45,X/46,X,r(X)(p11.22q12) mosaicism.

Ring X chromosomes that do not undergo inactivation may cause malformations and mental retardation. We report on a fetus with anencephaly, total dorsal rachischisis, and diaphragmatic hernia that was found to have a mosaic 45,X/46,X,r(X)(p11.22q12) karyotype. Fluorescent in situ hybridization (FISH) confirmed that the ring chromosome was X-derived. This report expands the phenotypic spectrum of mosaic monosomy X and small ring X chromosomes.

Abnormalities, Multiple↗

PubMed1998

Mucoepidermoid carcinoma of the parotid gland: a rare presentation in a young child.

Although mucoepidermoid carcinoma (MEC) is the most common malignant salivary gland neoplasm in childhood and adolescence, it is rarely found in children under the age of 10. A 6-year-old girl had an asymptomatic neck mass for 5 months. Clinical examination findings showed a 1.5-cm smooth and firm but mobile nontender mass located in the upper left anterior cervical triangle, clinically separate from the parotid gland. Ultrasound examination findings showed a vascular mass, with a cystic component, possibly within the tail of the parotid gland. An excisional biopsy was performed and frozen section showed a low-grade MEC. A left superficial parotidectomy was then performed. Final histopathologic examination showed one positive resection margin. Subsequently, reexcision of the surgical site and an upper modified neck dissection was undertaken. This unusual presentation of MEC as a neck mass in one of the youngest reported patients illustrates that the anatomic region for parotid tumors is large. Possibly some of these tumors may arise from heterotopic or accessory parotid tissue.

Carcinoma, Mucoepidermoid↗

PubMed1998

Sclerosing sweat-duct carcinoma (malignant syringoma) of the upper eyelid: a patient report with immunohistochemical and ultrastructural analysis.

Sclerosing sweat-duct carcinoma or malignant syringoma is a rare eyelid tumor. The authors report the first patient with sclerosing sweat-duct carcinoma involving the upper eyelid and present its immunohistochemical and ultrastructural features. The clinical features and the histopathologic and ultrastructural findings that distinguish this tumor from its benign counterparts are discussed. Sclerosing sweat-duct carcinomas are slow growing but locally invasive neoplasms that have a propensity to recur. Wide and deep surgical excision with frozen section evaluation of margins is recommended.

Biomarkers, Tumor↗

PubMed1996

Ultrasound backscatter microscope analysis of mouse melanoma progression.

The incidence and mortality rate of cutaneous melanoma continue to increase throughout the world, making the study of melanoma biology an important area of current research. While recent breakthroughs in transgenic mouse technology have led to promising mouse skin models of melanoma, there is presently no technique available for quantitatively studying subsurface melanoma progression, in vivo. We demonstrate the first application of an imaging method called ultrasound backscatter microscopy (UBM) for imaging early murine melanomas with spatial resolution of 30 microns axial and 60 microns lateral. Murine B16 F10 melanomas have been imaged from their earliest detection, over several days, until they are 2 to 5 mm in diameter. Melanoma dimensions measured by UBM were found to be in excellent agreement with those determined histopathologically on the excised tumours. The relative rms errors in UBM-determined melanoma height and width were found to be 8.7% and 4.2%, respectively. The mean rate of increase in tumour height of early murine melanoma was found to be 0.37 +/- 0.06 mm/day. Computer-generated volumetric renderings of melanomas have been produced from three-dimensional image data, allowing quantitative comparisons of tumour volumes to be made. Using a priori assumptions of ellipsoid tumour shape, the relative error in UBM-determined volume was shown to be less than 17%. These results should be of considerable interest to investigators studying melanoma biology using mouse skin models, and have implications in the use of high frequency ultrasound imaging for the clinical assessment of cutaneous melanoma.

Animals↗

PubMed1996

Colonic carcinoma presenting as an appendiceal abscess in a young woman.

A 38-year-old woman with stage T4N0M0 adenocarcinoma of the cecum presented with what seemed to be an appendiceal abscess. She had a 10-month history of intermittent abdominal pain in the right lower quadrant. Initial laparotomy revealed an abscess in that quadrant. The abscess was drained. A mass in the cecum, associated with dense fibrous tissue and abscess formation, was found on subsequent surgical exploration. Pathological examination revealed a well-differentiated mucinous adenocarcinoma of the cecum with transmural invasion. The lesion had replaced most of the vermiform appendix and was associated with a periappendiceal abscess. Colonic carcinoma masquerading as acute appendicitis or an appendiceal abscess is a well-recognized entity in the elderly but may be overlooked in younger patients because malignant disease is not suspected.

Abscess↗

PubMed1995

MIB-1 proliferative activity is a significant prognostic factor in primary thick cutaneous melanomas.

Although the Breslow measurement of tumor thickness of melanoma is the most significant predictor of survival, the biologic behavior of thick lesions remains unpredictable. MIB-1, a monoclonal antibody to a Ki-67 epitope, recognizes all proliferating cells. Unlike Ki-67 antibody, which requires frozen tissue, MIB-1 can be used on formalin-fixed tissue. Proliferation, measured by MIB-1 expression and mitotic index, was assessed as a prognostic factor in a group of patients with clinical stage I thick cutaneous melanoma (tumor thickness 4 mm or greater), for which predicted survival is low. From a melanoma data base, 97 patients with this type of melanoma were identified. Of these, 64 had lesional tissue available for study. The median follow-up time was 3.8 years (range 0.42-13.6 years). The percentage of MIB-1 reactivity was scored as low at less than 10% (n = 33), intermediate at 10% to 20% (n = 17), and high at greater than 20% (n = 14). Melanomas with high MIB-1 reactivity were associated with significantly poorer cause-specific survival compared with tumors with intermediate (p < 0.0001) or low MIB-1 reactivity (p = 0.0025). Multivariate analysis demonstrated that MIB-1 reactivity was a significant independent prognostic factor related to cause-specific survival (p = 0.0002) and was more sensitive than tumor thickness or mitotic index in this select group of high-risk patients. Identification of individuals with stage I thick cutaneous melanoma who are at risk of recurrent disease may improve patient management as new therapeutic modalities become available.

Adolescent↗

PubMed1995

bcl-2 protein expression in melanocytic neoplasms of the skin.

Since the discovery of bcl-2 proto-oncogene in follicular lymphomas, the protein product has been detected in a variety of normal tissues including skin, where it is expressed in basal keratinocytes. Recent studies indicate that bcl-2 protein is detected in nonlymphoid malignancies such as neuroblastoma and carcinomas of the lung and prostate. This study investigates the presence of bcl-2 protein in benign and malignant melanocytic neoplasms of the skin. Immunohistochemical analysis of bcl-2 protein expression was performed on 39 nevi and 60 malignant melanomas, including 21 metastases. There was diffuse strong immunopositivity for bcl-2 protein in 100% of nevi and 65% (43/60) of primary and metastatic melanomas. bcl-2 protein was diffusely expressed in 67% (30/39) of primary melanomas and 54% (11/21) of metastases. Although bcl-2 immunoreactivity was observed in all levels of primary cutaneous malignant melanomas, in 43% (9/21) of deep melanomas (Clark level > or = III), and 100% (7/7) of thick tumors (thickness > or = 4.00 mm), there was focal loss of immunoreactivity. Metastatic melanomas showed focal loss of bcl-2 expression in 10% (2/21) of cases and total loss of bcl-2 protein in 39% (8/21). We conclude from our results that bcl-2 protein is expressed by benign and malignant melanocytic tumors of the skin, but there is loss of bcl-2 protein expression with increasing tumor progression.

Biomarkers, Tumor↗

PubMed1993

Biodegradability and mechanical properties of poly-(beta-hydroxybutyrate-co-beta-hydroxyvalerate)-starch blends.

Wheat starch granules and poly-(beta-hydroxybutyrate-co-beta-hydroxyvalerate) [P(HB-co-HV), (19.1 mol% HV)] were blended at 160 degrees C. Increasing the starch content from 0 to 50% (wt/wt) decreased the tensile strength of P(HB-co-HV) from 18 MPa to 8 MPa and diminished flexibility as Young's modulus increased from 1,525 MPa to 2,498 MPa, but overall mechanical properties of the polymer remained in a useful range. A mixed microbial culture required more than 20 days to degrade 150-microns-thick samples of 100% P(HB-co-HV), whereas samples containing 50% (wt/wt) starch disappeared in fewer than 8 days. Starch granules degraded before P(HB-co-HV) did. Aerobic degradation proceeded more rapidly than anaerobic degradation.

Aerobiosis↗

PubMed1992

Effect of nitrogen limitation on long-side-chain poly-beta-hydroxyalkanoate synthesis by Pseudomonas resinovorans.

Pseudomonas resinovorans produced poly-beta-hydroxyalkanoates (PHAs) when grown on hydrocarbons but not on glucose. In a chemostat culture, the PHA composition was beta-hydroxybutyrate (C4)-beta-hydroxyhexanoate (C6)-beta-hydroxyoctanoate (C8)-beta-hydroxydecanoate (C10) (1:15:75:9) on octanoate and C4-C6-C8-C10 (8:62:23:7) on hexanoic acid. Contrary to the reported behavior of Pseudomonas oleovorans, the PHA accumulation rate increased under ammonium limitation on octanoate.

Acyltransferases↗

PubMed1991

Continuous Production of Long-Side-Chain Poly-beta-Hydroxyalkanoates by Pseudomonas oleovorans.

Shake flask experiments showed that Pseudomonas oleovorans began to be growth inhibited at 4.65 g of sodium octanoate liter, with total inhibition at 6 g liter. In chemostat studies with 2 g of ammonium sulfate and 8 g of octanoate liter in the feed, the maximum specific growth rate was 0.51 h, and the maximum specific rate of poly-beta-hydroxyalkanoate (PHA) production was 0.074 g of PHA g of cellular protein h at a dilution rate (D) of 0.25 h. When the specific growth rate (mu) was <0.3 h, the PHA composition was relatively constant with a C(4)/C(6)/C(8)/C(10) ratio of 0.1:1.7:20.7:1.0. At mu > 0.3 h, a decrease in the percentage of C(8) with a concomitant increase in C(10) monomers as mu increased was probably due to the effects of higher concentrations of unmetabolized octanoate in the fermentor. At D = 0.24 h and an increasing carbon/nitrogen ratio, the percentage of PHA in the biomass was constant at 13% (wt/wt), indicating that nitrogen limitation did not affect PHA accumulation. Under carbon-limited conditions, the yield of biomass from substrate was 0.76 g of biomass g of octanoate consumed, the yield of PHA was 0.085 g of PHA g of octanoate used, and 7.9 g of octanoate was consumed for each gram of NH(4) supplied. The maintenance coefficient was 0.046 g of octanoate g of biomass h. Replacement of sodium octanoate with octanoic acid appeared to result in transport-limited growth due to the water insolubility of the acid.

Journal Article↗

PubMed1990

Biosynthesis of Poly-beta-Hydroxyalkanoates from Pentoses by Pseudomonas pseudoflava.

The potential of Pseudomonas pseudoflava to produce poly-beta-hydroxyalkanoates (PHAs) from pentoses was studied. This organism was able to use a hydrolysate from the hemicellulosic fraction of poplar wood as a carbon and energy source for its growth. However, in batch cultures, growth was inhibited completely at hydrolysate concentrations higher than 30% (vol/vol). When P. pseudoflava was grown on the major sugars present in hemicelluloses in batch cultures, poly-beta-hydroxybutyric acid (PHB) accumulated when glucose, xylose, or arabinose was the sole carbon source, with the final PHB content varying from 17% (wt/wt) of the biomass dry weight on arabinose to 22% (wt/wt) of the biomass dry weight on glucose and xylose. Specific growth rates were 0.58 h on glucose, 0.13 h on xylose, and 0.10 h on arabinose, while the specific PHB production rates based on total biomass ranged from 0.02 g g h on arabinose to 0.11 g g h on glucose. PHB weight-average molecular weights were 640,000 on arabinose and 1,100,000 on glucose and xylose. The absolute amount of PHB in the cells decreased markedly when nitrogen limitation was relaxed by feeding ammonium sulfate at the end of the PHB accumulation stage of the arabinose and xylose fermentations. Copolymers of beta-hydroxybutyric and beta-hydroxyvaleric acids were produced when propionic acid was added to shake flasks containing 10 g of glucose liter. The beta-hydroxyvaleric acid monomer content attained a maximum of 45 mol% when the initial propionic acid concentration was 2 g liter.

Journal Article↗

PubMed1990

Production of poly-(beta-hydroxybutyric-co-beta-hydroxyvaleric) acids.

Alcaligenes latus, Alcaligenes eutrophus, Bacillus cereus, Pseudomonas pseudoflava, Pseudomonas cepacia, and Micrococcus halodenitrificans were found to accumulate poly-(beta-hydroxybutyric-co-beta-hydroxyvaleric) acid [P(HB-co-HV)] copolymer when supplied with glucose (or sucrose in the case of A. latus) and propionic acid under nitrogen-limited conditions. A fed-batch culture of A. eutrophus produced 24 g of poly-beta-hydroxybutyric acid (PHB) liter-1 under ammonium limitation conditions. When the glucose feed was replaced with glucose and propionic acid during the polymer accumulation phase, 17 g of P(HB-co-HV) liter-1 was produced. The P(HB-co-HV) contained 5.0 mol% beta-hydroxyvaleric acid (HV). Varying the carbon-to-nitrogen ratio at a dilution rate of 0.15 h-1 in a chemostat culture of A. eutrophus resulted in a maximum value of 33% (wt/wt) PHB in the biomass. In comparison, A. latus accumulated about 40% (wt/wt) PHB in chemostat culture under nitrogen-limited conditions at the same dilution rate. When propionic acid was added to the first stage of a two-stage chemostat, A. latus produced 43% (wt/wt) P(HB-co-HV) containing 18.5 mol% HV. In the second stage, the P(HB-co-HV) increased to 58% (wt/wt) with an HV content of 11 mol% without further addition of carbon substrate. The HV composition in P(HB-co-HV) was controlled by regulating the concentration of propionic acid in the feed. Poly-beta-hydroxyalkanoates containing a higher percentage of HV were produced when pentanoic acid replaced propionic acid.

Alcaligenes↗

PubMed1990

Strength training effects in prepubescent boys.

Possible changes in muscle size and function due to resistance training were examined in prepubertal boys. Thirteen boys (9-11 yr) volunteered for each of the training and control groups. Progressive resistance training was performed three times weekly for 20 wk. Measurements consisted of the following: 1 repetition maximum (RM) bench press and leg press; maximal voluntary isometric and isokinetic elbow flexion and knee extension strength; evoked isometric contractile properties of the right elbow flexors and knee extensors; muscle cross-sectional area (CSA) by computerized tomography at the mid-right upper arm and thigh; and motor unit activation (MUA) by the interpolated twitch procedure. Training significantly increased 1 RM bench press (35%) and leg press (22%), isometric elbow flexion (37%) and knee extension strength (25% and 13% at 90 degrees and 120 degrees, respectively), isokinetic elbow flexion (26%) and knee extension (21%) strength, and evoked twitch torque of the elbow flexors (30%) and knee extensors (30%). There were no significant effects of training on the time-related contractile properties (time to peak torque, half-relaxation time), CSA, or %MUA of the elbow flexors or knee extensors. There was, however, a trend toward increased MUA for the elbow flexors and knee extensors in the trained group. Strength gains were independent of changes in muscle CSA, and the increases in twitch torque suggest possible adaptations in muscle excitation-contraction coupling. Improved motor skill coordination (especially during the early phase of training), a tendency toward increased MUA, and other undetermined neurological adaptations, including better coordination of the involved muscle groups, are likely the major determinants of the strength gains in this study.

Anthropometry↗

PubMed1989

Production of Poly-beta-Hydroxyalkanoic Acid by Pseudomonas cepacia.

The possibility of using the nutritionally versatile bacterium Pseudomonas cepacia to produce poly-beta-hydroxyalkanoic acid was evaluated. Chemostat culture showed that growth of P. cepacia became nitrogen limited when the molar carbon-to-nitrogen ratio of the medium fed into the fermentor was above 15. When grown under nitrogen limitation in batch culture with fructose as the sole source of carbon, P. cepacia accumulated poly-beta-hydroxybutyric acid (PHB) in excess of 50% of the dry weight of its biomass. In batch culture, almost no PHB was produced until the onset of nitrogen limitation. After this point, PHB was produced at a linear rate of 0.12 g liter h (from a constant value of 1.6 g of cellular protein liter). PHB produced by P. cepacia had a weight-average molecular weight of 5.37 x 10 g mol and a polydispersivity index of 3.9. Poly(beta-hydroxybutyric acid-beta-hydroxyvaleric acid) copolymer was produced with a poly-beta-hydroxybutyric acid-poly-beta-hydroxyvaleric acid ratio of up to 30% by weight when propionic acid was added to the medium.

Journal Article↗