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Biomedical subjects

J K Roberts

Publications and source records attributed to J K Roberts.

At least 55 records · Page 3Linked to original sources
PubMed1991

Isolation and characterization of a soybean hsp70 gene.

Soybean, like many other organisms, responds to an increase in growth temperature by producing a set of new proteins, heat shock proteins. The heat shock proteins have been classified into several categories according to their molecular weight. Data are presented on the isolation, sequence characterization, and expression of a 70 kDa heat shock protein gene from soybean. A cDNA clone was isolated using a Drosophila hsp70 clone as a heterologous probe, and the cDNA was used for isolation of the soybean gene corresponding to the cDNA. The structure of this soybean is very similar to the hsp70 genes from other organisms. It has several sequences in the 5' untranscribed region that are similar to the well characterized heat shock consensus element found in other organisms. These heat shock consensus elements have the expected position relative to the start of transcription. Unlike hsp70-like genes previously isolated from other plants, this gene does not have an intron. This protein shows high amino acid sequence similarity to other hsp70 proteins from such diverse organisms as Drosophila, rat, and Xenopus. This soybean gene is only expressed during heat shock. In addition to the hsp70 gene isolated here, there is evidence for many other hsp70-like genes in soybean.

Amino Acid Sequence↗
PubMed1991

Elongation and termination reactions of protein synthesis on maize root tip polyribosomes studied in a homologous cell-free system.

We show that the control of gene expression at the level of elongation and termination of protein synthesis can be observed in vitro. Free cytoplasmic polyribosomes were isolated from maize (Zea mays) root tips, and translated in root tip extracts that had been fractionated with ammonium sulfate to contain elongation factors, and be depleted in initiation factors. The root tip extract performs elongation and termination reactions as efficiently as wheat germ extracts. The translation products of the maize system are the same as made in vivo. The dependence of these in vitro elongation and termination reactions on pH was determined. Total protein synthesis in this system exhibits an optimum at pH approximately 7.5. However, the pH dependence of rates of synthesis of individual proteins is not at all uniform; many polyribosomes become stalled when translated at low pH. These data were compared with the elongation and termination capacity of polyribosomes isolated from oxygenated and hypoxic root tips (tissue having, respectively, high and low cytoplasmic pH values). We observed an inverse relationship between the relative abundance of many specific translatable mRNAs in polyribosomes of hypoxic root tips, and the relative rates of elongation and termination reactions on the different mRNAs at low pH in vitro. These results suggest that changes in intracellular pH in hypoxic root tips can be sensed directly by the translational machinery and thereby selectively modulate gene expression.

Journal Article↗
PubMed1990

Observation of uridine triphosphate:glucose-1-phosphate uridylyltransferase activity in maize root tips by saturation transfer 31P-NMR. Estimation of cytoplasmic PP.

Saturation transfer 31P nuclear magnetic resonance was used to estimate the unidirectional rate of phosphorus exchange between Glc-1-P and UDPGlc in maize root tips. The rate was determined to be approx. 4 mumol.min-1 per g fresh weight. This estimated rate is much higher than net rates of other reactions in glucose metabolism (e.g., more than 10-times faster than the maximal glycolytic flux in this tissue). Furthermore, exchange between Glc-1-P and UDPGlc was not significantly inhibited by the metabolic poison KCN. We conclude that the unidirectional rate of conversion of Glc-1P to UDPGlc is much faster than the net rate of UDPGlc synthesis--the UTP:Glc-1-P uridylyltransferase reaction is near-equilibrium in vivo. From the equilibrium constant for this transferase reaction and the concentrations of Glc-1-P, UTP and UDPGlc, the level of cytoplasmic PPi was estimated to be approx. 10 nmol.g-1.

Cytoplasm↗
PubMed1990

Predation and control of laboratory populations of the snail Biomphalaria glabrata by the freshwater prawn Macrobrachium rosenbergii.

Laboratory experiments were conducted on predation by the giant freshwater prawn, Macrobrachium rosenbergii, on Biomphalaria glabrata, a snail intermediate host of human schistosomiasis. Prawns greater than 22 mm carapace length could consume snails of any size. Smaller prawns exhibited a size-specific upper limit on the size of snail they could kill. Below the maximum size of prey consumed, little selectivity for prey size was demonstrated. All prawns heavier than 2.5 g killed the largest size of snail offered (16 mm diameter). Consumption, in terms of the numbers of snails killed, and the snails' wet weight and percentage of prawn body weight eaten per day, increased with prawn size. Large prawns consumed snails at a high rate (39% of body weight per day). Population experiments demonstrated that a prawn of 25 mm carapace length could eliminate 95% of a population of 80 snails in a 20-1 aquarium within 20 days and all snails by day 40. A prawn of 15 mm carapace length could not eliminate all snails. Large snails (24% of the initial population) had some protection from predation because of their size. Although the snails bred continuously, no snails were able to recruit to these populations in the presence of small prawns. In contrast, snail populations in control aquaria without prawns expanded to a mean of 919 snails by the end of the experiment (day 70). Since M. rosenbergii are voracious predators on B. glabrata, exhibit considerable habitat overlap with the snail prey, and are likely to treat snails as highly preferred food, further experimentation on these prawns in the context of biological control of schistosomiasis is warranted. The ready availability of prawns through established prawn hatcheries and the synergistic use of these prawns in aquaculture may ensure the reliability of stocking procedures and meet the standards of availability and cost-effectiveness required of a biological control agent. Polyculture of Macrobrachium with fin fish (Tilapia) indicates that these prawns may be a particularly useful control agent in aquacultural environments.

Animals↗
PubMed1990

Nonsquamous cell malignancies of the paranasal sinuses.

Nonsquamous cell malignancies represent half of paranasal sinus cancers. Since 1975, 103 patients have been treated at The Cleveland Clinic Foundation for sinus malignancies. Forty-nine patients had nonsquamous cell malignancies: 12 (25%) sarcoma, 10 (20%) adenoid cystic carcinoma, 9 (18%) adenocarcinoma, 9 (18%) lymphoma, and 9 (18%) miscellaneous tumors. Ten patients presented with T1 or T2 disease at the primary site, 16 with T3, and 23 with T4. Ten patients had primary ethmoid malignancies; the remainder of the tumors originated in the maxillary sinus. Five patients had evidence of regional or distant metastases at presentation. Twelve patients were free of disease after initial management. Three patients with recurrent disease were salvaged with additional therapy. Two patients died of complications in the immediate postoperative period. Patients with less extensive primary lesions have an improved prognosis. Survival was similar for the different histologic diagnoses.

Adenocarcinoma↗
PubMed1990

Inverted papillomas and associated squamous cell carcinomas.

Inverted papillomas of the nose and paranasal sinuses are found to be associated with squamous cell carcinomas in a small percentage of cases. The records of forty-six patients treated for inverted papillomas in these areas over a 10-year period were reviewed. Eleven patients (24%) were found to have squamous cell carcinoma, and one carcinoma in situ, in relationship to the inverted papillomas. This is a much higher percentage than generally reported. Four of these patients were found to have inverted papillomas coincidentally in surgical specimens resected for squamous cell carcinoma. Patients with squamous cell carcinoma were found to be in older age groups, were more likely to manifest epistaxis than the more common unilateral nasal obstructive symptoms, and had less time between the onset of symptoms and presentation than those with inverted papillomas alone. The clinical presentation, treatment, and outcome of inverted papillomas and squamous cell carcinomas in association with inverted papillomas are discussed.

Adult↗
PubMed1989

Near-total laryngectomy with epiglottic reconstruction. Long-term results.

A previous report reviewed the technique and indications for near-total laryngectomy with epiglottic reconstruction in the management of squamous cell carcinoma of the glottis. This approach permits removal of most of both vocal folds, with immediate reconstruction using the epiglottis without the need for stenting or multistage procedures. Forty-eight patients underwent the procedure and were followed up for at least 2 years or until death. Seventeen underwent the surgery for recurrence after failure of radiation therapy for cure. Complications included one wound infection and one laryngocutaneous fistula. All patients underwent decannulation, with little or no compromise of swallowing. All but 1 now have functional voices. Of 8 patients with recurrence, 6 have been salvaged. Two patients died of disease. The value of near-total laryngectomy with epiglottic reconstruction for management of glottic cancer is reviewed.

Adult↗
PubMed1989

Observation of Cytoplasmic and Vacuolar Malate in Maize Root Tips by C-NMR Spectroscopy.

The accumulation of malate by maize (Zea mays L.) root tips perfused with KH(13)CO(3) was followed by (13)C nuclear magnetic resonance spectroscopy. In vivo nuclear magnetic resonance spectra contained distinct signals from two pools of malate in maize root tips, one at a pH approximately 5.3 (assigned to the vacuole) and one at a pH > 6.5 (assigned to the cytoplasm). The ratio of cytoplasmic to vacuolar malate was lower in 12 millimeter long root tips than in 2 millimeter root tips. The relatively broad width of the signals from C1- and C4-labeled vacuolar malate indicated heterogeneity in vacuolar pH. During the 3 hour KH(13)CO(3) treatment, (13)C-malate accumulated first primarily in the cytoplasm, increasing to a fairly constant level of approximately 6 millimolar by 1 hour. After a lag, vacuolar malate increased throughout the experiment.

Journal Article↗
PubMed1989

Compartmentation of Nucleotides in Corn Root Tips Studied by P-NMR and HPLC.

Corn (Zea mays L.) root tips were subjected to different conditions so that nucleotide levels varied over a wide range. Levels of nucleotides in corn root tips were measured using (31)P nuclear magnetic resonance (NMR) spectroscopy and high performance liquid chromatography. Results indicate: (a) Similar amounts of NTP and sugar nucleotides were observed by in vivo NMR and in extracts. In contrast, a significant amount of NDP observed in root tip extracts was not detected by in vivo NMR. Thus, for a given sample, [NTP]/[NDP] ratios determined in vivo by (31)P-NMR are always higher than ratios observed in extracts, deviating by approximately 4-fold at the highest ratios. The NMR-invisible pool of NDP appeared quite metabolically inert, barely changing in size as total cell NDP changed. We conclude that NDP in corn root tips is compartmented with respect to NMR visibility, and that it is the NMR-visible pool which responds dynamically to metabolic state. The NMR-invisible NDP could either be immobilized (and so have broad, undetectable NMR signals), or be complexed with species that cause the chemical shift of NDP to change (so it does not contribute to the NMR signal of free NDP), or both. (b) (31)P-NMR cannot distinguish between bases (A, U, C, and G) of nucleotides. HPLC analysis of root tip extracts showed that the relative amount of each base in the NTP and NDP pools was quite constant in the different samples. (c) In extracts, for each of the nonadenylate nucleotides, [NTP]/[NDP] was linearly proportional to [ATP]/[ADP], indicating near equilibrium in the nucleoside diphosphokinase (NDPK) reaction. However, the apparent equilibrium constants for the phosphorylation of GDP and UDP by ATP were significantly lower than 1, the true equilibrium constant for the NDPK reaction. Thus, for a given sample, [ATP]/[ADP] approximately [CTP]/[CDP] > [UTP]/[UDP] > [GTP]/[GDP]. This result suggests that the different NDPs in corn root tips do not have equal access to NDPK.

Journal Article↗
PubMed1989

Dependence of Ethanolic Fermentation, Cytoplasmic pH Regulation, and Viability on the Activity of Alcohol Dehydrogenase in Hypoxic Maize Root Tips.

We examined the role of alcohol dehydrogenase (ADH) in the metabolism and survival of hypoxic maize (Zea mays L.) root tips. The dependence of the rate of ethanolic fermentation, cytoplasmic pH, and viability on the activity of ADH in maize root tips during extreme hypoxia was determined. Maize lines with ADH activities differing over about a 200-fold range were studied. Effects of genetic background were controlled by comparing pairs of F4 progeny of crosses between mutant (low ADH activity) and reference inbred lines. The capacity of hypoxic root tips to perform ethanolic fermentation exhibited a dependence on ADH activity only at activities found in Adh 1 nulls. The ability of maize root tips to withstand prolonged and extreme hypoxia was like-wise independent of ADH activity, except at the lowest activities. Root tips that exhibited lower tolerance of hypoxia had more acidic cytoplasm during extreme hypoxia. We conclude that the activity of ADH in normal maize root tips does not limit the capacity for energy production via fermentation, and does not determine viability under extreme hypoxia. The significance of the induction of ADH activity in plants by hypoxia is discussed.

Journal Article↗
PubMed1989

Advantages of the rotary door flap in laryngotracheal reconstruction: is skeletal support necessary?

Most attempts at laryngeal reconstruction have sought to reestablish skeletal support. Bone and cartilage grafts have been used for this purpose, but they have often failed to maintain position in the larynx and/or trachea following reconstruction, and they tend to be reabsorbed. The rotary door flap can provide an undelayed, one-stage epithelial resurfacing of the larynx and trachea while simultaneously restoring luminal support without the need for transfer of cartilage or bone. Luminal support for the trachea is provided by the bulk, turgor, and anterior traction of the intact sternohyoid muscle, which serves as the carrier for the rotated skin island. During inspiration the intact muscle, whose points of attachment are anterior to the plane of the larynx and trachea, contracts and tends to open the airway to provide dynamic luminal support. The need for internal stenting is minimized. The technique is described and experience in 20 patients is presented.

Adolescent↗
PubMed1989

Evaluation of syncope from head and neck cancer.

Five patients suffering from recurrent syncope in association with metastatic squamous cell carcinoma of the head and neck were examined. Two patients had exhaustive diagnostic work-up for syncope, which eventually disclosed previously undiagnosed, recurrent squamous cell carcinoma. Case reports describe glossopharyngeal neuralgia, a well recognized cause of syncope in the head and neck cancer patient, characterized by acute unilateral head or neck pain preceding each syncopal episode. The literature on the diagnosis of syncope is reviewed, and the syncopal mechanisms unique to the head and neck cancer patient are analyzed and discussed. A diagnostic approach to syncope in head and neck cancer is proposed.

Carbamazepine↗
PubMed1989

Squamous cell carcinoma of the paranasal sinuses: the Cleveland Clinic experience 1977-1986.

Fifty-four of 103 malignancies of the paranasal sinuses treated at the Cleveland Clinic Foundation between 1977 and 1986 were squamous cell carcinomas. Six arose from the ethmoid sinus and 48 from the maxillary sinus. Of the maxillary sinus patients, 11 presented with T1 or T2 lesions, 20 with T3, 16 with T4, and 7 of these had nodal disease. Treatment was surgery and/or radiation therapy. There was local recurrence in 25 of 48 maxillary sinus patients and in 1 of 6 ethmoid patients. Overall 5-year survival was 38.2% in the maxillary sinus group: T1, 100.0%; T2, 85.7%; T3, 31.8%; and T4, 6.7%. Three of six patients with ethmoid tumors were cured. There was a statistical trend for better prognosis in those patients presenting with ethmoid primaries, with early lesions, treated with both radiation and surgery, and with history of inverting papilloma. There were complications of treatment in 10 patients, four of which resulted in death. Local control was the major problem for these patients; therefore, early detection and aggressive local treatment are desirable.

Adult↗
PubMed1989

Religion and epilepsy.

A study of 57 consecutive patients with epilepsy who were attending a neurological epilepsy clinic at a general hospital, was carried out. A preliminary analysis of the data revealed that 33% had at some time been treated for a psychological disorder, 51% had 'normal' and 60% 'abnormal' interests in religion and related belief systems. Fifty-one percent had undergone a significant change in their interest in these matters in the past (religious conversion). A significant association was found between the 'abnormal' group and psychopathology, and religious conversion. These associations were not found with the 'normal' group.

Adolescent↗
PubMed1989

Cancer of the periauricular region.

Cutaneous carcinoma of the auricular and periauricular region can be diagnosed early and often can be cured; however, many of these tumors become difficult to treat because of local spread and regional metastasis. Those tumors that are not treated early often require more aggressive treatment with ear canal resection, partial temporal bone resection, or even parotidectomy and radiation therapy. Mohs histographic surgery combined with conventional excision affords the best marginal control for local eradication of these tumors.

Ear Neoplasms↗
PubMed1988

P-NMR Spectroscopy of Roots of Intact Corn Seedlings.

The application of (31)P nuclear magnetic resonance spectroscopy to the study of metabolism in roots of intact corn seedlings is described. (31)P-NMR spectra of developmentally distinct parts of primary roots of whole seedlings are presented. The spectra are of quality comparable to those of excised pieces of plant tissue.

Journal Article↗
PubMed1988

Effect of Indoleacetic Acid- and Fusicoccin-Stimulated Proton Extrusion on Internal pH of Pea Internode Cells.

Using (31)P nuclear magnetic resonance spectroscopy, we followed cytoplasmic and vacuolar pH in pea (Pisum sativum cv Alaska) internode segments during treatment with indoleacetic acid (IAA) or fusicoccin (FC) in continuously perfused, oxygenated buffer. Although IAA and FC induced normal H(+) extrusion, elongation, and glucan synthase activity responses during the measurements, neither the cytoplasmic nor the vacuolar pH showed significant change at any time between 5 minutes and 1 to 3 hours of treatment. Changes in cytoplasmic pH as small as about 0.04 pH unit were detected after treatment with 1-naphthyl acetate. Therefore, cytoplasmic pH changes do not appear to mediate IAA or FC stimulation of H(+) extrusion or other metabolic responses to these effectors.

Journal Article↗