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Biomedical subjects

J J Hart

Publications and source records attributed to J J Hart.

At least 19 recordsLinked to original sources
PubMed2006

Work of breathing using high-flow nasal cannula in preterm infants.

OBJECTIVE: To compare the work of breathing (WOB) in premature neonates supported with high-flow nasal cannula (HFNC) and nasal continuous positive airway pressure (NCPAP). STUDY DESIGN: Eighteen preterm neonates <2.0 kg on HFNC or NCPAP support were studied in a random order. A ventilator was used to deliver 6 cm H2O of NCPAP with nasal prongs. High-flow nasal cannula delivered with Vapotherm (VAPO) at 3, 4 and 5 l/min was used. Tidal ventilation was obtained using respiratory inductance plethysmography calibrated with face-mask pneumotachography. An esophageal balloon estimated pleural pressure from which changes in end distending pressure were calculated. Inspiratory, elastic and resistive WOB and respiratory parameters were calculated. RESULTS: No differences were found in the WOB for all settings. Changes in end distending pressure did not vary significantly over all device settings except VAPO at 5 l/min. CONCLUSION: In these preterm infants with mild respiratory illness, HFNC provided support comparable to NCPAP.

Continuous Positive Airway Pressure↗
PubMed2003

Cadmium absorption and retention by rats fed durum wheat (Triticum turgidum L. var. durum) grain.

A whole-body radioassay procedure was used to assess the retention and apparent absorption by rats of Cd in kernels of durum wheat (Triticum turgidum L. var. durum) harvested from plants grown hydroponically in 109Cd-labelled nutrient solution. Wholegrain wheat, containing 5 micromol Cd (570 microg)/kg dry weight labelled intrinsically with 109Cd, was incorporated into test meals fed to rats that had been maintained on diets containing marginally adequate, adequate or surplus levels of Zn (0.12 mmol (8 mg), 0.43 mmol (28 mg) or 1.55 mmol (101 mg) Zn/kg respectively), and either 0 or 50 g durum wheat/kg. Regardless of diet, all rats consumed about 99 % of the test meal offered. In rats fed diets without wheat, initial Cd absorption averaged 7.7, 4.6 and 2.4 % of the dose when the diet contained 0.12 mmol (8 mg), 0.43 mmol (28 mg) or 1.55 mmol (101 mg) Zn/kg diet respectively. In rats fed wheat-containing diets, initial Cd absorption averaged 3.8 and 2.6 % of the dose when dietary Zn concentration was 0.12 mmol (8 mg) and 0.43 mmol (28 mg)/kg diet respectively. The amount of Cd retained in the body at 15 d postprandial was <2 % of the dose in all rats, and decreased as Zn in the diet increased. Even at 15 d postprandial, 32 to 44 % of the Cd retained in the body was still in the gastrointestinal tract. The results show that: (1) the bioavailability to rats of Cd in wholegrain durum wheat was depressed when wholegrain wheat was part of the regular diet; (2) increased intake of dietary Zn lowered Cd absorption and retention; (3) retention of Cd in the body at 15 d postprandial from diets containing adequate Zn was <1.3 %.

Analysis of Variance↗
PubMed2001

High- and low-affinity zinc transport systems and their possible role in zinc efficiency in bread wheat.

There is considerable variability among wheat (Triticum aestivum L.) cultivars in their ability to grow and yield well in soils that contain very low levels of available Zn. The physiological basis for this tolerance, termed Zn efficiency, is unknown. We investigated the possible role of Zn(2+) influx across the root cell plasma membrane in conferring Zn efficiency by measuring short-term (65)Zn(2+) uptake in two contrasting wheat cultivars, Zn-efficient cv Dagdas and Zn-inefficient cv BDME-10. Plants were grown hydroponically under sufficient and deficient Zn levels, and uptake of (65)Zn(2+) was measured over a wide range of Zn activities (0.1 nM-80 microM). Under low-Zn conditions, cv BDME-10 displayed more severe Zn deficiency symptoms than cv Dagdas. Uptake experiments revealed the presence of two separate Zn transport systems mediating high- and low-affinity Zn influx. The low-affinity system showed apparent K(m) values similar to those previously reported for wheat (2-5 microM). Using chelate buffered solutions to quantify Zn(2+) influx in the nanomolar activity range, we uncovered the existence of a second, high-affinity Zn transport system with apparent K(m) values in the range of 0.6 to 2 nM. Because it functions in the range of the low available Zn levels found in most soils, this novel high-affinity uptake system is likely to be the predominant Zn(2+) uptake system. Zn(2+) uptake was similar for cv Dagdas and cv BDME-10 over both the high- and low-affinity Zn(2+) activity ranges, indicating that root Zn(2+) influx does not play a significant role in Zn efficiency.

Biological Transport↗
PubMed1998

Coronary artery ectasia.

Coronary artery ectasia is an uncommon expression of coronary artery atherosclerosis and other diseases. It occurs in about 1.4 percent of the adult population. It is not distinguishable from obstructive coronary artery disease in severity of angina, clinical presentation, electrocardiograms, mortality, or outcome of coronary artery surgery. Although there is debate, treatment is indicated in the form of chronic warfarin anticoagulation to prevent coronary thrombus formation and its sequelae. Aspirin therapy may suffice in asymptomatic individuals.

Anticoagulants↗
PubMed1997

Nephrologists' and internal medicine physicians' expectations of renal dietitians and general clinical dietitians.

OBJECTIVE: To document and compare nephrologists' and internal medicine physicians' expectations of renal dietitians and general clinical dietitians. DESIGN: Subjects completed a mailed survey. Respondents provided demographic information and used a 5-point Likert scale to note whether each of 14 job functions was appropriate for general clinical dietitians, renal dietitians, or both. SUBJECTS: Five hundred forty-one physicians registered with the Ohio State Medical Board (OSMB) were surveyed. Within this group were 283 nephrologists (the population of nephrologists registered with the OSMB) and 258 internal medicine physicians (selected randomly by the OSMB). A total of 133 physicians (25%) returned the survey; 119 surveys were usable: 70 from nephrologists and 49 from internists. STATISTICAL ANALYSES PERFORMED: A composite variable was created by coding and summing physicians' responses regarding dietitian job functions. This variable was averaged for both physician categories. A t test was conducted to compare composite variable results between the two physician groups. RESULTS: At least 50% of nephrologists and internists agreed that both types of dietitians should conduct nutrition assessments, determine patients' energy needs, evaluate medication-nutrient interactions, recommend diet and tube-feeding orders, instruct patients about physician-ordered diets, and teach nutrition concepts to hospital interns. Few physicians agreed that either type of dietitian should order diets, tube feedings, or diet instructions. APPLICATIONS/CONCLUSIONS: Clinical dietitians can educate physicians about dietitians roles informally in their institutions and formally by supporting programs like The American Dietetic Association Physician Nutrition Education Program. In addition, dietetics educators can hone their students' communication and problem-solving skills to promote positive physician-dietitian interaction.

Allied Health Personnel↗
PubMed1997

Oral pulsed calcitriol protocol reduces the prevalence of hyperparathyroidism in a PD unit.

A quality assessment (QA) activity revealed that the percentage of parathyroid hormone (PTH) levels above 300 micrograms/dL was higher in the peritoneal dialysis (PD) unit than in the hemodialysis (HD) unit (44% vs 27%). To reduce the proportion of patients with a target PTH above 200 micrograms/dL, a protocol that emphasized control of the serum phosphate level, standard pulsed doses of calcitriol, and increased patient education was created for the management of renal osteodystrophy. Serum calcium, phosphate, and PTH levels were obtained according to the protocol from July 1994 through June 1996. The percentage of patients achieving a PTH level below 200 micrograms/dL increased from 40% in June 1994 to 57% in June 1996. Significant differences were found in PTH levels at baseline and at test times 1, 2, and 3. Hypercalcemia (Ca > 12) occurred in 4% of the 532 Ca levels drawn during the study period and were due to breaches of protocol. In conclusion, we have confirmed previous work indicating that pulsed calcitriol can control elevated PTH levels in PD patients. Furthermore, we have developed a protocol that can be used as a QA tool to reduce the prevalence of hyperparathyroidism in the outpatient PD setting without inducing excess hypercalcemia.

Administration, Oral↗
PubMed1996

Painful, swollen, and erythematous hands and feet.

The patient described herein had 3 features known to be associated with secondary erythermalgia: 1) onset during pregnancy, 2) hypertension, and 3) verapamil treatment (6). Unusual was the fact that while the patient's condition did not respond to aspirin consistently or completely, the skin biopsy did show arteriolar fibromuscular intimal proliferation, which is usually seen with erythromelalgia. Also unusual was the recurrence of symptoms with a second pregnancy 2 years after the presentation reported herein. The syndrome resolved completely within 1 year of delivery. The platelet count was monitored for 4 year after the initial resolution of symptoms (which included the second pregnancy and its associated recurrence of symptoms) and was never higher than 350 x 10(9)/liter. The literature is confusing in mixing of terminology concerning these 3 clinically similar syndromes. The classifications as outlined herein are the emerging standards. A working knowledge of the definitions of these 3 syndromes is critical for appropriate diagnosis and treatment.

Adult↗
PubMed1996

Transient synovitis of the hip in children.

Transient synovitis is the most common cause of acute hip pain in children three to 10 years of age. Children with this condition typically present with hip pain for one to three days, accompanied by limping or the refusal to bear weight. Transient synovitis has an uncertain etiology and remains a diagnosis of exclusion. First, septic arthritis must be ruled out, since femoral head destruction, degenerative arthritis and permanent deformity can occur if septic arthritis is not treated promptly. Septic arthritis should be suspected in a patient with severe pain or spasm on hip movement or palpation, a temperature higher than 37.5 degrees C (99.5 degrees F) and an erythrocyte sedimentation rate of 20 mm per hour or greater. Hip aspiration is the diagnostic procedure of choice if septic arthritis is suspected. Treatment of transient synovitis consists of bed rest and nonsteroidal anti-inflammatory drugs, with regular temperature checks to exclude the onset of fever. If significant pain and limping persist seven to 10 days after the initial presentation, the patient should be reevaluated.

Arthritis, Infectious↗
PubMed1996

Pediatric gastroesophageal reflux.

Gastroesophageal reflux occurs in up to 65 percent of healthy infants. The initial differentiation of physiologic reflux with harmless spitting up from pathologic reflux is often difficult to achieve. Gastroesophageal reflux is caused by transient and intermittent lower esophageal sphincter relaxations unrelated to swallowing. Many tests are available for the diagnosis of gastroesophageal reflux, each with specific indications and limitations. Although no one test is always best, 24-hour esophageal pH monitoring remains the "gold standard" for diagnosis. Its major limitations are its inability to detect reflux for up to two hours following feedings because of the neutralizing effect of the feeding, the lack of correlation with clinical gastroesophageal reflux severity, the expense and the invasive nature of the test. Treatment is determined by the specific presentation. Management of physiologic reflux consists of parental reassurance and counseling about feeding and positioning techniques. Approaches to the management of pathologic reflux range from the use of histamine H2-receptor blockers and prokinetic medications to surgery in severe cases.

Child↗
PubMed1992

Transport kinetics and metabolism of exogenously applied putrescine in roots of intact maize seedlings.

Putrescine metabolism, uptake, and compartmentation were studied in roots of hydroponically grown intact maize (Zea mays L.) seedlings. In vivo analysis of exogenously applied putrescine indicated that the diamine is primarily metabolized by a cell wall-localized diamine oxidase. Time-dependent kinetics for putrescine uptake could be resolved into a rapid phase of uptake and binding within the root apoplasm, followed by transport across the plasma membrane that was linear for 30 to 40 minutes. Concentration-dependent kinetics for putrescine uptake (between 0.05 and 1.0 millimolar putrescine) appeared to be nonsaturating but could be resolved into a saturable (V(max) 0.397 micromoles per gram fresh weight per hour; K(m) 120 micromolar) and a linear component. The linear component was determined to be cell wall-bound putrescine that was not removed during the desorption period following uptake of [(3)H]putrescine. These results suggest that a portion of the exogenously applied putrescine can be metabolized in maize root cell walls by diamine oxidase activity, but the bulk of the putrescine is transported across the plasmalemma by a carrier-mediated process, similar to that proposed for animal systems.

Journal Article↗
PubMed1992

Effect of inorganic cations and metabolic inhibitors on putrescine transport in roots of intact maize seedlings.

The specificity and regulation of putrescine transport was investigated in roots of intact maize (Zea mays L.) seedlings. In concentration-dependent transport studies, the kinetics for putrescine uptake could be resolved into a single saturable component that was noncompetitively inhibited by increasing concentrations of Ca(2+) (50 micromolar to 5 millimolar). Similarly, other polyvalent cations, including Mg(2+) (1.8 millimolar) and La(3+) (200 micromolar), almost completely abolished the saturable component for putrescine uptake. This suggests that putrescine does not share a common transport system with other divalent or polyvalent inorganic cations. Further characterization of the putrescine transport system indicated that 0.3 millimolar N-ethyl-maleimide had no effect on putrescine uptake, and 2 millimolar p-chloromercuribenzene sulfonic acid only partially inhibited transport of the diamine (39% inhibition). Metabolic inhibitors, including carbonylcyanide-m-chlorphenylhydrazone (20 micromolar) and KCN (0.5 millimolar), also partially inhibited the saturable component for putrescine uptake (V(max) reduced 48-60%). Increasing the time of exposure to carbonylcyanide-m-chlorphenylhydrazone from 30 minutes to 2 hours did not significantly increase the inhibition of putrescine uptake. Electrophysiological evidence indicates that the inhibitory effect on putrescine uptake by these inhibitors is correlated to a depolarization of the membrane potential, suggesting that the driving force for putrescine uptake is the transmembrane electrical potential across the plasmalemma.

Journal Article↗
PubMed1992

Transport Interactions between Paraquat and Polyamines in Roots of Intact Maize Seedlings.

Interactions between absorption of paraquat and the polyamines putrescine, cadaverine, and spermine in roots of intact maize (Zea mays L. cv 3377 Pioneer) seedlings were examined. Concentration-dependent kinetics for paraquat and putrescine influx were similar and both kinetic curves could be resolved into a linear and a saturable component. The linear component was previously shown to represent cell wall/membrane binding. The saturable components for paraquat and putrescine uptake, which represent influx across the plasmalemma, had K(m) values of 98 and 120 micromolar, respectively, and V(max) values of 445 and 456 nanomoles per gram fresh weight per hour, respectively. Lineweaver-Burk transformation of the saturable component of paraquat influx in the presence of varying concentrations of putrescine indicated that the diamine competitively inhibited the saturable component of paraquat uptake. Reciprocal experiments similarly demonstrated that paraquat competitively inhibited the saturable component of putrescine uptake. Competitive inhibition of both paraquat and putrescine influx could also be demonstrated with the diamine cadaverine, which has a charge distribution similar to that of paraquat and putrescine. In contrast, the larger, tetravalent polyamine spermine appeared to noncompetitively inhibit the influx of paraquat and putrescine. These results strongly suggest that paraquat enters maize root cells via a carrier system that normally functions in the transport of diamines with a charge distribution similar to that of paraquat.

Journal Article↗
PubMed1990

Similar Photosynthetic Performance in Low Light-Grown Isonuclear Triazine-Resistant and -Susceptible Brassica napus L.

Triazine-resistant plants grown under moderate to high photon flux density (PFD) conditions exhibit decreased photon yield, decreased light-saturated O(2) evolution and slower growth than triazine-susceptible plants. In this study we tested the hypothesis that the comparable growth previously observed in resistant and susceptible Brassica napus L. lines grown under low PFD was accompanied by comparable photon yield and light-saturated O(2) evolution. We measured photon yield, O(2) flash yield, fluorescence decay kinetics, fluorescence transient kinetics, and quenching components, F(v)/F(m) and light saturated O(2) evolution in leaf disks of low PFD-grown triazine-resistant and susceptible B. napus isogenic lines. Results indicated that slow electron transfer from the primary to secondary quinone electron acceptors of photosystem II was still present in the resistant line but photon yield and light-saturated O(2) evolution were similar in the two B. napus lines. We conclude that the alteration in the D1 protein that confers resistance does not necessarily cause decreased photosynthetic performance. Decreased photon yield in resistant plants grown at high PFD is not a direct consequence of the alteration in D1, but represents secondary damage.

Journal Article↗
PubMed1990

High Light-Induced Reduction and Low Light-Enhanced Recovery of Photon Yield in Triazine-Resistant Brassica napus L.

Triazine-resistant and -susceptible Brassica napus L. plants grown under low photon flux density (PFD) have previously been shown to exhibit a similar photon yield. In contrast, high PFD-grown resistant plants have a lower photon yield than high PFD-grown susceptible plants (JJ Hart, A Stemler [1990] Plant Physiol 94: 1295-1300). In this work we tested the hypothesis that high PFD can induce a differential decrease in photon yield in low PFD-grown plants. We measured photon yield, variable fluorescence/maximum fluorescence, and O(2) flash yield in low PFD-grown resistant and susceptible leaf discs before and after exposure to high PFD exposure. The results demonstrated that high PFD exposure results in a greater decrease in photosystem II (PSII) activity in resistant plants. Characteristics of recovery and other evidence suggest that the differential decrease in PSII efficiency in resistant leaf discs is caused by photoinhibitory damage. We propose that the differential reduction in photon yield and photosynthesis often observed in resistant plants is the result of increased sensitivity to photoinhibition.

Journal Article↗
PubMed1990

Paranoid states: classification and management.

In terms of both nosology and treatment the paranoid states have long proved a thorny but irresistible enigma to psychiatrists. Recent evidence suggests that at least one of these conditions, paranoia, not only may be eminently treatable, but also merits serious consideration as a clinical entity distinct from other functional psychoses.

Adult↗
PubMed1990

Pheochromocytoma.

Pheochromocytoma is a rare, potentially lethal cause of hypertension that is surgically reversible. Diagnosis may be difficult, because catecholamine release is often intermittent and the location of the lesion is variable. Management consists of blocking alpha-adrenergic stimulation preoperatively. This controls hypertension both before and during surgery. It also allows expansion of the intravascular volume, preventing postsurgical hypotension. Associated arrhythmias must also be controlled. After surgery, routine evaluation for tumor recurrence is essential.

Adrenal Gland Neoplasms↗
PubMed1989

A system for accelerated provision of hearing aids to residents of homes for the elderly.

A study was undertaken to detect undiagnosed deafness in elderly people, living in Part III Residential Homes in North Tees, South Tees and Hartlepool Health Districts, to provide hearing aids and to estimate the subsequent success in rehabilitation. The residents were referred by the senior staff in the homes and assessed by a doctor and audiology technician in a domiciliary setting. Those found to have a significant hearing impairment were prescribed hearing aids without formal pure tone audiometry. A pilot study compared the method of hearing evaluation employed with such conventional testing. Six months after fitting, the degree of compliance with aiding was assessed. The results show a significant level of undiagnosed deafness in the community and, with this method of provision, an acceptance rate of 41.2 per cent of those recommended for aiding at six months which is higher than suggested by previous similar studies of this population.

Aged↗