Determination of intracellular pH and compartmentation using diffusion-weighted NMR spectroscopy with pH-sensitive indicators.

The intracellular pH (pHi) of a series of cancer cell lines was determined using the pH-sensitive indicators imidazole (Im) or histidine (His) and diffusion-weighted (DW) proton NMR spectroscopy. The DW method allows the observation at high magnetic field gradient values of only the slow-moving (intracellular) components, thus ensuring complete separation between intra- and extracellular components. Using the chemical shift difference (deltadelta) between the imidazole ring C2-H and C4(5)-H peaks, we were able to measure the pHi independently of chemical shift standardization. With His, the cell lines gave pHi values of approximately 6.5-7.0, whereas with Im, a second, more acidic compartment (pHi = 5.5-5.8) was also observed. An inverse correlation was also found between pHi and the intracellular lactate concentration. This method may be applicable to in vivo pH determinations.     

Clinical experience with metolazone in fifty-two African patients: synergy with frusemide

The use of metolazone (Zaroxolyn), a new diuretic, in fifty-two African patients is described. The drug was found to be safe and moderately effective when used alone, but combined with frusemide it proved to be of great value in patients whose fluid retention was refractory to other diuretics.     

Standardization of CDI-mediated DTPA-coupling to IgG and IgG2a antibodies for 113mIn labeling

A systematic analysis of various factors involved in the CDI-mediated coupling of DTPA to IgG have been carried out, in order to optimize the labeling yield of a monoclonal antibody labeled to high specific activity. Various CDI-to-DTPA ratios were tested, followed by a range of DTPA (activated) to IgG ratios. Specific activities as high as 600 Ci/mmol could be obtained following labeling with 113mIn, when an IgG : DTPA : CDI ratio of 0.01 : 1:20 was used. Other aspects, such as the volume of each of the reactants, the pH and the reaction times, were also standardized to yield a labeled IgG2a (KS1/4) that could be consistently tested for biodistribution and tumor-binding.     

Simultaneous primary total hip arthroplasty and contralateral revision hip arthroplasty: role for use of femoral head autograft

We report the outcome of revision hip arthroplasty for patients with acetabular bone loss in whom the femoral head retrieved from arthritic contralateral hip during the same anesthesia was used as autograft for acetabular reconstruction. Thirty-two hips in 16 patients with a mean age of 63.8 years (range, 43-79 years) were followed for an average of 3.5 years. All primary arthroplasties were successful. Evidence of autograft incorporation was found in all except 2 patients. The acetabular component failed and required revision in the latter 2 patients. The use of femoral head autograft in a select group of patients with symptomatic arthritis of hip and a failed prosthetic hip with severe bone loss in the contralateral side is a viable option. However, this technique should not be applied to acetabular reconstructions in which protected weight-bearing in the postoperative period may be necessary.     

Characterization of the specific binding of prolactin to binding sites in the seminal vesicle of the rat.

The binding of ovine prolactin to the seminal vesicles of the rat has been characterized and found to be a saturable process, dependent upon time, temperature, protein concentration of the seminal vesicle and divalent ions. Its specificity was similar to that reported for prolactin binding to other organ preparations. Time and temperature studies of the specific binding revealed that equilibrium was reached after 16 h at 5 degrees C or 4 h at 19 degrees C. Nonspecific binding was also dependent on time and temperature. This parameter has been reported to comprise up to 70% of the total binding to various organ-binding sites, but it fell to below 20% after 48 h at 19 degrees C, thus demonstrating the high degree of specificity required of target organ receptors. From degradation studies it was evident that no damage occurred to the free hormone during incubation for up to 70 h at 5 degrees C or 16 h at 19 degrees C. However, there seems to be a difference in the susceptibility of bound and free ovine prolactin to damage during incubation: after 40 h at 19 degrees C the hormone in the supernatant fraction had lost 85% of its binding ability, whereas a high level of specific binding was evident in the pellet. A Scatchard plot of competitive binding studies revealed two classes of binding sites, of which the high-affinity, low-capacity site was similar to that reported previously and consistent with a physiological receptor for prolactin in the seminal vesicle of the rat.