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Biomedical subjects

M Baum

Publications and source records attributed to M Baum.

At least 361 records · Page 20Linked to original sources
PubMed1989

Axial heterogeneity of rabbit proximal tubule luminal H+ and basolateral HCO3- transport.

The present in vitro microperfusion study examined whether the rates of the apical membrane Na+-H+ antiporter and basolateral membrane Na(HCO3)3 symporter vary along the length of the proximal tubule. Initial proximal convoluted tubules (PCT obtained within 0.5 mm from the glomerulus), mid-PCT (PCT without glomerular attachments) and cortical proximal straight tubules were examined. The rate of either the apical or basolateral membrane acidification mechanism was measured from the initial rate of change of intracellular pH after a change in either the luminal or bathing solution. Intracellular pH was measured fluorometrically using the pH-sensitive dye (2',7')-bis(carboxyethyl)-(5,6)-carboxyfluorescein. The rate of bicarbonate exit across the basolateral membrane was examined by imposing either a sodium or bicarbonate gradient. There was no difference between initial and mid-PCT, but the rate of change in cell pH was 30% slower in PST in both series. The rate of sodium-dependent apical proton secretion was examined by changing the sodium concentration in the lumen. There was no difference in sodium-dependent apical proton secretion in initial vs. mid-PCT, but the rate fell by 70% in the proximal straight tubule (PST). These differences were not due to a difference in buffer capacity in these segments. These data are consistent with a homogeneous rate of apical Na+-H+ antiporter and basolateral Na(HCO3)3 activity along the rabbit PCT, but a lower rate in the PST.

Amiloride↗
PubMed1989

Breast cancer--which treatment?

Posters presented at the International Symposium on Endocrine Therapy are reviewed to address the question of which adjuvant treatment should be used for early breast cancer.

Breast Neoplasms↗
PubMed1989

Cancer Research Campaign Adjuvant Breast Trial for patients under 50.

The objectives of the Cancer Research Campaign Adjuvant Breast Trial are to determine whether the administration of a course of adjuvant tamoxifen, or ablation of ovarian function, results in a prolongation of time to recurrence or death, for women aged under 50 years and treated for operable breast cancer. The basis and aims of the trial are discussed.

Adult↗
PubMed1989

Advanced breast cancer. A randomised trial of epidoxorubicin at two different dosages and two administration systems.

Sixty-two women with advanced breast cancer have been entered into a randomised trial comparing bolus injection with 24-h infusion of epirubicin given as a dose of either 20 mg or 40 mg weekly, of which 57 patients are eligible for analysis. Bolus injection proved significantly more successful than prolonged infusion in response rate, time to first event and survival. No significant differences appeared between the two doses using these measures, however 40 mg weekly was significantly more toxic than 20 mg weekly. Epirubicin given as a weekly 20 mg bolus injection appears both effective and relatively free from toxicity.

Breast Neoplasms↗
PubMed1989

The Cancer Research Campaign trials of adjuvant therapy for early breast cancer.

It is now assumed that for many women there has already been dissemination of tumour at the time of diagnosis of their early breast cancer. Systemic treatment is required if a cure is sought. The use of perioperative cyclophosphamide and long-term tamoxifen, either as single agents or in combination, has been investigated in the Cancer Research Campaign Breast Adjuvant Trial. A total of 2,230 women were recruited to the study. A benefit has been seen for both agents. The implications of these results for the current treatment of women with early breast cancer and for the design of future trials are discussed.

Aged↗
PubMed1989

Prospective evaluation of a low maintenance policy for semipermanent silicone vascular access catheters.

Twenty-six women had semipermanent vascular access catheters (VACs) inserted to allow weekly outpatient infusion chemotherapy for advanced breast cancer. VACs were maintained without occlusive dressings, antibiotics, repeated flushings or heparin for a total of 2294 patient days (range 6 to 217 days, median 55 days). Three exit site and one subcutaneous tunnel infection occurred but no patient suffered septicaemia. VACs allowed both blood sampling and drug administration on 267 occasions and drug administration only on 19 occasions. No catheter became completely occluded.

Breast Neoplasms↗
PubMed1989

[The PEEP wave: an automated technic for bedside determination of the volume/pressure ratio in the lungs of ventilated patients].

The volume/pressure (V/P) ratio in the lungs has been reported to be useful in the adjustment of mechanical ventilation equipment to suit individual pulmonary mechanics. Most of the techniques used so far (e.g. the super-syringe technique) need an apneic period of approximately 60-120 s, in which the pulmonary gas volume is reduced by the continuing oxygen uptake. Thus, a bias of 200-400 ml in volume is superimposed on the record. In contrast to the super-syringe technique, a new automatic procedure has been developed for which no apneic period is needed. This technique is called the PEEP wave technique: it is based on the imbalance between inspiratory and expiratory volumes after a sudden change in PEEP. The software of a Dräger Evita respirator was adapted to allow automatic application of a special sequence of respiratory cycles with stepwise increase and decreases in PEEP between two preselectable borderline levels. The equipment is switched to the next PEEP level when the difference between two consecutive expiratory tidal volumes is less than 15 ml. After the highest level of PEEP is reached the procedure is reversed until PEEP returns to its initial value. Constant inspiratory tidal volumes (Vti) are achieved by a high pressure servo valve (HPSV) under conditions of chocked flow, resulting in inspiratory tidal volumes which are independent of back-pressure. Thus, only the difference in expiratory tidal volumes (Vte) before and after a PEEP change is necessary to determine gain and loss in lung volume (delta FRC).(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1989

[Biphasic positive airway pressure (BIPAP)--a new form of augmented ventilation].

Two modes of combining spontaneous breathing and mechanical ventilation are already in use: periodic mechanical support always followed by a period of spontaneous breathing (intermittent mandatory ventilation; IMV) and mechanical support of each spontaneous breath (inspiratory assistance; IA). Biphasic positive airway pressure (BIPAP), in contrast, is based on neither of the above mentioned principles. It is rather a mixture of pressure controlled (PC) ventilation and spontaneous breathing, which is unrestricted in each phase of the respiratory cycle. The BIPAP circuit switches between a high (Phi) and a low (Plo) airway pressure level in an adjustable time sequence. At both pressure levels the patient can breathe spontaneously in a continuous positive airway pressure system (CPAP). The volume displacement caused by the difference between Phi and Plo and the BIPAP frequency (F) contribute the mechanical ventilation to total ventilation. Duration of the Phi and the Plo phases can be independently adjusted. Similar to the I:E ratio during controlled ventilation, the phase time ratio (PhTR) is calculated as the ratio between the durations of the two pressure phases. A PhTR greater than 1:1 is called IR-BIPAP. A BIPAP system can be set up either as a continuous flow system, or as a demand valve system. A continuous-flow BIPAP system consists of a high-flow CPAP system, a reservoir bag, and a pneumatically controlled membrane valve in the expiratory limb. A magnetic valve operated by an impulse generator switches between Phi and Plo, controlling the pop-off pressures of the expiratory valve.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗