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Biomedical subjects

B L Graham

Publications and source records attributed to B L Graham.

12 recordsLinked to original sources
PubMed1992

Effect of volume history on changes in DLcoSB-3EQ with lung volume in normal subjects.

The purpose of this study was to determine the relationship between the three-equation diffusing capacity for carbon monoxide (DLcoSB-3EQ) and lung volume and to determine how this relationship was altered when maneuvers were immediately preceded by a deep breath. DLcoSB-3EQ maneuvers were performed in nine healthy subjects either immediately after a deep breath or after tidal breathing for 10 min. The maneuvers consisted of slow inhalation of test gas from functional residual capacity to 25, 50, 75, or 100% of the inspiratory capacity and, without breath holding, slow exhalation to residual volume. After either a deep breath or tidal breathing, we found that DLcoSB-3EQ decreased nonlinearly with decreasing lung volume. At all lung volumes, DLcoSB-3EQ was significantly greater when measured after a deep breath than after tidal breathing. This effect increased as lung volume decreased, so that the greatest difference between DLcoSB-3EQ after a deep breath and that after tidal breathing occurred at the lowest lung volume. We conclude that a deep breath or spontaneous sigh has a role in reestablishing the pathway for gas exchange during tidal breathing.

Adult↗
PubMed1992

Effects of ventilation inhomogeneity on DLcoSB-3EQ in normal subjects.

In patients with airflow obstruction, we found that ventilation inhomogeneity during vital capacity single-breath maneuvers was associated with decreases in the three-equation single-breath CO diffusing capacity of the lung (DLcoSB-3EQ) when breath-hold time (tBH) decreased. We postulated that this was due to a significant resistance to diffusive gas mixing within the gas phase of the lung. In this study, we hypothesized that this phenomenon might also occur in normal subjects if the breathing cycle were altered from traditional vital capacity maneuvers to those that increase ventilation inhomogeneity. In 10 normal subjects, we examined the tBH dependence of both DLcoSB-3EQ and the distribution of ventilation, measured by the mixing efficiency and the normalized phase III slope for helium. Preinspiratory lung volume (V0) was increased by keeping the maximum end-inspiratory lung volume (Vmax) constant or by increasing V0 and Vmax. When V0 increased while Vmax was kept constant, we found that the tBH-independent and the tBH-dependent components of ventilation inhomogeneity increased, but DLcoSB-3EQ was independent of V0 and tBH. Increasing V0 and Vmax did not change ventilation inhomogeneity at a tBH of 0 s, but the tBH-dependent component decreased. DLcoSB-3EQ, although independent of tBH, increased slightly with increases in Vmax. We conclude that in normal subjects increases in ventilation inhomogeneity with increases in V0 do not result in DLcoSB-3EQ becoming tBH dependent.

Adult↗
PubMed1991

Identification of spliced baculovirus RNAs expressed late in infection.

Previous to this study, the Autographa californica multicapsid nuclear polyhedrosis virus (AcMNPV) was known to express only one spliced RNA (spliced IE1 or IE0). We have conducted an analysis of RNA expressed during infection of Spodoptera frugiperda cells with AcMNPV and have identified a set of five additional spliced RNAs expressed late in infection. A reverse transcription-polymerase chain reaction analysis was used to confirm the identification of the LS (late, spliced) RNAs. S1 nuclease and primer extension analyses were used to map the transcription initiation sites of LS RNAs. LS1 and LS2 initiated at positions -138 and -117, respectively (relative to the IE0 +1 transcription start site). Both LS1 and LS2 contain an additional cistron potentially encoding a small, highly basic polypeptide. LS3 (-79), LS4 (-22), and LS5 (+51/52) RNAs encode only the predicted downstream IE0 ORF. Although several baculovirus late gene consensus transcription initiation sites (ATAAG) were identified within this region, only LS5 initiated at one of these conserved motifs. An S1 nuclease analysis was done to determine whether unspliced precursors of LS RNAs could be detected. Early in infection, a greater proportion of IE0 RNA was detected in the spliced form; however, during the late phase of infection a significantly greater amount of unspliced precursor forms of LS RNAs was observed.

Amino Acid Sequence↗
PubMed1990

Effect of a deep breath on gas mixing and diffusion in the lung.

We examined the effect of a previous deep breath on both inert gas mixing and the single breath diffusing capacity (DLCOSB) during submaximal single breath maneuvers in normal subjects. Single breath washouts were performed either immediately after a deep breath or after breathing tidally for 10 min. Maneuvers consisted of inhaling test gas from functional residual capacity to 50% inspiratory capacity and, after either 0 or 6 s of breath holding, exhaling slowly back to residual volume. We measured the Fowler dead space, the Phase III slope of the alveolar plateau of the He washout (delta He/L), the amplitude of the cardiogenic oscillations (Oc), closing capacity, mixing efficiency (Emix) and DLCOSB using the three equation method. For maneuvers immediately after a deep breath we found that delta He/L was steeper and the Oc were larger for washouts with 6 s but not 0 s of breath holding, while Emix was significantly lower and DLCOSB significantly higher for both the 0 s and the 6 s breath holding maneuvers. We conclude that a deep breath increases DLCOSB but simultaneously also increases convective-dependent inhomogeneity in the lung.

Adult↗
PubMed1990

Pulmonary diffusing capacity in adult cystic fibrosis: reduced positional changes are partially reversed by hyperoxia.

In seated adult cystic fibrosis (CF) patients, vascular recruitment of the relatively normal regions of the pulmonary circulation could occur in response to vascular destruction or hypoxia elsewhere in the pulmonary vasculature, thus limiting overall reductions in the single breath CO diffusing capacity (DLcoSB) with advancing disease. The purpose of this study was to determine the extent to which pulmonary capillary recruitment limits reductions in DLcoSB in seated adult cystic fibrosis patients, to define the role of hypoxia, and to develop strategies to improve detection of diffusion abnormalities in this disease. In normal subjects and adult CF patients breathing room air, and in a subgroup, after breathing both 40% and 100% O2 for 20 min, we measured changes (compared to sitting) in the three equation DLcoSB by changing transvascular pressure either with 15 degrees head down position (15 degrees HD), or with high negative inspiratory pressure (HNIP). In CF patients breathing room air, the changes in DLcoSB with both 15 degrees HD and HNIP were significantly smaller (p less than 0.01) than in controls and the positional changes correlated with the degree of airway obstruction. Although CF patients had no significant positional changes in diffusional resistance (1/DLcoSB) breathing room air, the positional changes in 1/DLcoSB after breathing 100% O2 for 20 min were similar in magnitude to the positional changes in normal subjects. We conclude that compensatory pulmonary capillary recruitment occurs in the relatively normal regions of the pulmonary vasculature breathing room air in the resting seated position in CF patients, thus minimizing reductions in DLcoSB in the seated position. This accounts for reduced responses of DLcoSB to both position and HNIP. The improved positional changes in 1/DLcoSB breathing hyperoxic gas mixtures in CF patients suggests that the vascular recruitment breathing room air is partly due to hypoxic vasoconstriction rather than due solely to fixed pathological changes in the pulmonary vasculature.

Adolescent↗
PubMed1990

Patients with localized pancreatic adenocarcinoma in central Mississippi: a retrospective analysis of survival.

Factors influencing the survival of central Mississippi patients with adenocarcinoma of the pancreas were analyzed by a retrospective analysis of the two largest tumor registries in the state. The authors report that this Mississippi data agree with very recent reports describing significant benefit from chemoradiotherapy in localized disease, and suggests a less fatalistic attitude of the medical community towards localized pancreatic carcinoma is appropriate.

Adenocarcinoma↗
PubMed1989

Focal glomerulosclerosis in Hodgkin's disease necessitating peritoneal dialysis.

A 16-year-old white boy had nephrotic syndrome due to focal segmental glomerulosclerosis six months before the diagnosis of Hodgkin's disease was established. Peritoneal dialysis was necessary for volume control after one month of unsuccessful therapy with high doses of corticosteroids. Nephrosis remitted after two courses of chemotherapy.

Adolescent↗
PubMed1988

Surgery in small cell lung cancer.

Surgery in small cell lung cancer (SCLC) was abandoned in the late 1960s but is currently being cautiously reassessed, after the Armed Forces Asymptomatic Pulmonary Nodule Study demonstrated an unexpectedly prolonged 5-year survival (36%) with surgery. Subsequent prospective studies have reported five-year survival following resection in 22 to 83% of patients with Stage I disease and in 0 to 50% of patients with Stages II and III disease. Ten percent of patients with SCLC may be amenable to this approach. Additional patients may become candidates for resection following intensive combination chemotherapy. The optimal postoperative management remains unsettled. Combination chemotherapy and prophylactic cranial irradiation is recommended following complete resection. Postoperative thoracic irradiation may benefit patients with pathologically involved mediastinal nodes. Correlation of clinical response with our new understanding of the molecular biology of SCLC may further improve our approach to this disease.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1979

Peripheral airways obstruction in patients with rhinitis.

Nine young lifetime nonsmoking patients with symptoms of rhinitis but without any history of asthma or wheezing and nine age-matched healthy lifetime nonsmoking control subjects were studied with respect to subdivisions of lung volume, forced vital capacity, forced expiratory volume (1.0 sec), and flow-volume curves breathing air, and also breathing a mixture of 80% helium--20% oxygen (He-O2) from which were obtained airflows at 50% VC (Vmax50), the percentage increase in Vmax50 breathing He-O2 as compared to air (deltaVmax50) and the point where He-O2 and airflow-volume curves became identical (Visov). No significant differences between the two groups in age, subdivisions of lung volume or forced expiratory airflow rates were recorded. However, deltaVmax50 was significantly lower in the patients (16.4 +/- 12.0) compared to the controls (47.7 +/- 16.4) (p less than .001) and Visov was higher in the patients (28.4 +/- 14.9) as compared to the controls (14.4 +/- 7.6) (p less than .01). After bronchodilator therapy Vmax50 increased in the control subjects (p less than .005) but not in the patients and deltaVmax 50 decreased in the control group but was unchanged in the rhinitis patients. These results suggest that patients with rhinitis who have normal airflow rates may have peripheral airways obstruction not readily reversible with bronchodilators.

Adult↗
PubMed1978

A preliminary study in the detection of cardiac disorders via phase-invariant signature algorithm of ECG.

The present paper presents a simple and unambiguous computer-assisted method for the detection of cardiac disorders by processing the electrocardiogram. A new technique "Phase Invariant Signature Algorithm (PISA)", has been described, which is useful in the detection of cardiac abnormalities by investigating certain statistical properties of the measured waveform of ECG in a "phase-locked" fashion. This method of detection of abnormalities in the heart was used in the changes in the hypoxic action potential and in the ECG due to ionic changes and ischemia in the heart of cats and dogs. The signature of the normal ECG or action potential was straight-line. Any change in the waveform of ECG or action potential was detected as spikes in the signature. This method of detection of cardiac abnormalities does not require a priori reference to any standard ECG. The results indicate that this new method is capable of detecting cardiac disorders at an early stage and hence a higher sensitivity than the presently available type of ECG analysis. This method is in the developmental stage and further studies are being carried out.

Animals↗