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Biomedical subjects

C Pickett

Publications and source records attributed to C Pickett.

11 recordsLinked to original sources
PubMed2001

The role of follow-up radiographic studies in nonoperative management of spleen trauma.

The management of splenic injuries has evolved significantly in recent years from an operative to a nonoperative approach in stable patients with blunt abdominal trauma. The management of these patients with serial radiographic studies before hospital discharge remains controversial. We reviewed the management of 90 patients retrospectively who were admitted to our Level II trauma center with splenic injuries secondary to blunt trauma to determine the value of serial radiographic studies. Forty-seven (52%) patients underwent immediate laparotomy. Forty-three (48%) patients were managed conservatively without surgery. All nonoperative patients had an initial CT of the abdomen to evaluate their abdominal injuries. Among the 43 patients managed without surgery 31 had no follow-up radiographic studies. Twelve patients had follow-up studies before discharge. Two of these 12 patients subsequently underwent splenectomy. Both had developed hypotension, tachycardia, and a decreasing hematocrit, which prompted their repeat radiographic studies. Ten patients had no change in their clinical status and showed no significant change in the radiographic injury pattern to the spleen. One patient who was initially managed nonoperatively became hemodynamically unstable with increasing abdominal pain and subsequently underwent splenectomy without follow-up radiographic studies. The remaining 30 patients who had no follow-up studies had no significant change in their clinical abdominal examinations and had no further complications from their splenic injuries. Routine follow-up radiographic evaluations are not necessary in the nonoperative management of stable patients with splenic injuries.

Adolescent↗
PubMed1998

Toxicity and efficacy of defined doses of CD4(+) donor lymphocytes for treatment of relapse after allogeneic bone marrow transplant.

Donor lymphocyte infusions (DLI) can induce remissions in patients who have relapsed after allogeneic bone marrow transplantation (BMT). However, DLI frequently also result in significant acute and/or chronic graft-versus-host disease (GVHD). Several clinical and experimental lines of evidence have suggested that CD8(+) T cells play a critical role in the pathogenesis of GVHD. To develop methods to reduce the incidence of GVHD associated with DLI, we administered defined numbers of CD4(+) donor T cells after ex vivo depletion of CD8(+) lymphocytes to 40 patients with relapsed hematologic malignancies after allogeneic BMT. Cohorts of patients received 0.3, 1.0, or 1.5 x 10(8) CD4(+) cells/kg. Overall, 12 of 38 patients (32%) evaluable for toxicity developed acute or chronic GVHD. However, 6 of 27 patients (22%) receiving 0.3 x 10(8) CD4 cells/kg developed GVHD compared with 6 of 11 patients (55%) who received >/=1.0 x 10(8) CD4 cells/kg (P = .07). Treatment-related mortality was low (3%), with 1 death related to infection in the setting of immunosuppression for GVHD. Disease responses after CD4(+) DLI were documented in 15 of 19 patients (79%) with early-phase chronic myelogenous leukemia (CML) relapse, 5 of 6 patients (83%) with relapsed multiple myeloma, and 1 patient with myelodysplasia. For patients with early-phase CML relapse, the Kaplan-Meier probability of achieving complete cytogenetic remission was 87% and the probability of complete molecular response was 78% at 1 year after DLI. The median time to complete cytogenetic response and molecular response in patients with CML was 13 weeks (range, 9 to 30 weeks) and 34 weeks (range, 10 to 56 weeks), respectively. The median time to response in patients with multiple myeloma was 26 weeks (range, 15 to 62 weeks). All patients in this trial who developed GVHD demonstrated tumor regression, but the presence of GVHD was not required for patients to achieve a response, because 48% of responding patients never developed evidence of GVHD. Two patients with CML who did not respond at dose level 1 subsequently achieved complete cytogenetic remission after a second infusion of CD8-depleted cells at dose level 2. In patients with evidence of mixed hematopoietic chimerism who achieved a complete remission after DLI, cytogenetic analysis of marrow cells also demonstrated conversion to complete donor hematopoiesis in all evaluable patients. These studies suggest that relatively low numbers of CD8-depleted donor lymphocytes are effective in inducing complete remissions in patients with stable-phase CML and multiple myeloma who have relapsed after allogeneic BMT. Because of the relatively low risk of toxicity associated with the infusion of defined numbers of CD4(+) donor cells, further studies can be undertaken in the setting of persistent minimal residual disease to prevent relapse after allogeneic BMT.

Adult↗
PubMed1996

Pharmacodynamics and enantioselective pharmacokinetics of carprofen in the cat.

The pharmacodynamics and enantioselective pharmacokinetics of the arylpropionic acid non-steroidal anti-inflammatory drug, carprofen, were investigated in cats after administration of the racemic mixture (rac-carprofen) at dose rates ranging from 0.7 to 4.0 mg kg-1 intravenously and subcutaneously. A low dose of rac-carprofen (0.7 mg kg-1) partially inhibited the rise in skin temperature at a site of acute inflammation but had no effect on the ex vivo synthesis of serum thromboxane (Tx) B2. A higher dose (4.0 mg kg-1) inhibited oedematous swelling, although the response was statistically significant at only one time, and also reduced the ex vivo synthesis of serum TxB2 for 12 hours after intravenous injection or 24 hours after subcutaneous injection. The main features of carprofen pharmacokinetics were a low distribution volume, a relatively long elimination half-life, the predominance of the R(-) enantiomer and a bioavailability (after subcutaneous dosing) of 100 per cent and 92 per cent, respectively, after doses of 0.7 and 4.0 mg kg-1. On the basis of these data, it is suggested that a dose of 4.0 mg kg-1 by both intravenous and subcutaneous routes should be evaluated in clinical subjects.

Animals↗
PubMed1991

Improved arterial oxygenation with feed restriction in rapidly growing broiler chickens.

1. Rapidly growing broiler chickens fed ad lib. until 56 days, but feed restricted until 60 days of age, had higher arterial oxygen saturations, lower respiratory frequencies, total ventilations that were not different, and higher tidal volumes compared to those fully fed for 56 days. 2. Arterial oxygen saturation correlated negatively with respiratory frequency, but was not related to total ventilation or tidal volume. 3. Hypoventilation appeared not to be the cause of arterial oxygen desaturation. 4. Arterial oxygen desaturation correlated with the degree of right ventricular hypertrophy.

Animal Feed↗
PubMed1990

Spontaneous hypoxaemia and right ventricular hypertrophy in fast growing broiler chickens reared at sea level.

1. At 6 weeks of age, the time of most rapid body growth, fast growing broiler chickens showed more right ventricular hypertrophy than slower growing chickens. 2. The degree of right ventricular hypertrophy was directly related to blood haematocrit and indirectly related to arterial oxygen saturation (estimated in the chickens using an ear oximeter designed for man). 3. When oxygen saturation was estimated sequentially from 6 to 17 weeks of age, mean oxygenation improved with age, partly due to the death of the chickens with the worst saturations, but also because of an improvement in oxygenation of the survivors.

Altitude↗
PubMed1989

The relationship between rapid growth and pulmonary hemodynamics in the fast-growing broiler chicken.

Very fast-growing (VFG) broiler chickens tend to have marked right ventricular hypertrophy when compared with slower growing chickens. We hypothesized that, in the setting of rapid growth, a hypoxic stimulus would cause greater pulmonary hypertension and right ventricular hypertrophy (RVH). We have studied the relationship between artial oxygenation (SaO2), RVH, and pulmonary artery pressure (Ppa) in 28 awake VFG chickens. We found that the hypoxemic chickens had pulmonary hypertension and that the Ppa was linearly related to the SaO2. The relationship between Ppa and RVH, however, was best described by a broken line (p less than 0.05). Thus, at higher pressures, the RVH seemed excessive for a given Ppa. We have also studied the effects of reducing FIO2 on Ppa, systemic pressure, cardiac output, and calculated total pulmonary resistance (TPR) in lightly anesthetized fast-growing and normal chickens. We found that normal chickens and fast growers had similar TPR in room air, but that the fast growers had a greater increase in TPR than did the normal chickens in response to hypoxia (p less than 0.05). Finally, we placed 2-wk-old normal and VFG chicks in a hypobaric chamber set at "10,000 feet" for 2 wk and found that the VFG but not the normal chickens developed marked RVH in response to the hypoxia. However, the RVH in the fast-growing chickens could be prevented by restricting their diet, and hence their growth. We conclude that hypoxemia probably caused the pulmonary hypertension and RVH in the fast-growing chickens, but that the rapid growth appeared to act as an important amplifier of this response.

Air Pressure↗
PubMed1984

Obstructive sleep apnea in hypothyroidism.

To determine the incidence and frequency of sleep apnea in persons with hypothyroidism, 11 consecutive patients with newly diagnosed disease were studied before and during thyroid hormone replacement therapy. Nine patients had episodes of apnea, with the number of episodes per hour of sleep ranging from 17 to 176 (mean, 71.8). Six of the nine patients were obese and had 99.5 episodes per hour compared with 16.3 episodes per hour in the 3 nonobese patients (p less than 0.02). After 3 to 12 months of thyroxine replacement therapy, mean apnea frequency decreased from 71.8 +/- 18.0 (SE) to 12.7 +/- 6.1 episodes per hour, without reduction in body weight. There were fewer changes in sleep stage per hour during treatment (22.1 +/- 4.9) than pretreatment (57.6 +/- 14.5). Carbon dioxide response tests done under non-loaded and flow-resistive loaded conditions before and during thyroxine replacement therapy showed increases in the loaded respiratory effort and ventilation during thyroxine treatment. Sleep apnea episodes are common in persons with untreated hypothyroidism, even with normal lung function. Thyroxine replacement therapy decreases apnea frequency, even without change in body weight.

Adult↗
PubMed1981

Disturbed sleep and prolonged apnea during nasal obstruction in normal men.

Anecdotal observations suggested that poor quality of sleep is a frequent complaint during upper respiratory infections (URI). Nasal obstruction occurs frequently during URI and causes sleep apnea in some infants. Sleep apnea disrupts normal sleep and could explain the complaints of poor sleep quality during URI in adults. Accordingly, 10 normal men had full night recordings of sleep stages and breathing rhythm before and during nasal obstruction. The order of obstructed and nonobstructed nights was randomized after a standard acclimatization night. During nasal obstruction, time spent in the deep sleep stages decreased from 90 +/- 11.2 (SEM) to 71 +/- 12.9 min (p less than 0.05), whereas significantly more time was spent in Stage 1 sleep (p less than 0.03). This loss of deep sleep during obstruction was associated with a twofold increase in sleep arousals and awakening (p less than 0.01) resulting from an increased (p less than 0.02) number of apneas (34 +/-19 during control sleep versus 86 +/- 34 during obstructed sleep). Apneas of 20 to 39 s in duration became 2.5 times more frequent (p less than 0.05) during obstruction. Oxygen saturation was studied in the last 4 subjects using an ear oximeter. Desaturation (SaO2 less than 90%) occurred 27 times during control sleep compared with 255 times during obstructed sleep. These desaturation episodes occurred only during apneas. All men complained of poor sleep quality during nasal obstruction. We concluded that apneas, sleep arousals and awakenings, and loss of deep sleep occur during nasal obstruction and may explain complaints of poor sleep quality during URI.

Adult↗