MR and fluorescence imaging of gadobutrol-induced optical clearing of red fluorescent protein signal in an in vivo cancer model

Multimodality registration of optical and MR images in the same tissue volume in vivo may be enabled by MR contrast agents with an optical clearing (OC) effect. The goals of this study were to (a) investigate the effects of clinical MR contrast agent gadobutrol (GB) and its combinations as a potential OC agent assisting in fluorescence intensity (FI) imaging in vivo and (b) evaluate MRI as a tool for imaging of topical or systemic application of GB for the purpose of OC. Subcutaneous tumor xenografts expressing red fluorescent marker protein were used as disease models. MRI was performed at 1 T ¹H MRI using T₁-weighted 3D gradient-echo (T1w-3D GRE) sequences to measure time-dependent MR signal intensity changes by region of interest analysis after image segmentation. Topical application of 1.0 M or 0.7 M GB-containing OC mixture with water and dimethyl sulfoxide showed similar 30–40% increases of tumor FI during the initial 15 min. Afterwards, the OC effect of GB on FI and tumor/background FI ratio showed a decrease over time in the case of 1.0 M GB, unlike the 0.7 M GB mixture, which resulted in a steady increase of FI and tumor/background ratio for 15–60 min. The use of T1w-3D GRE MR pulse sequences showed that concentrated 1.0 M GB resulted in MR signal loss of the skin due to high magnetic susceptibility and that signal loss coincided with the OC effect. Intravenous injection of 0.3 mmol GB/kg resulted in a rapid but transient 40% increase of FI of the tumors. Overall, 1 T MRI enabled tracking of GB-containing OC compositions on the skin surface and tumor tissue, supporting the observation of a time-dependent FI increase in vivo.     

Efficacy and safety of pentoxifylline in geriatric patients with intermittent claudication

The effects of pentoxifylline on intermittent claudication were evaluated at a dose of 1200 mg/day in an open-label twelve-week study on geriatric patients with chronic occlusive arterial disease (COAD). Standardized treadmill testing and clinical signs and symptoms of COAD were followed up before and during drug administration. Twenty-four subjects with a mean age of 73.5 years, capable of walking between 20 and 200 meters on the treadmill, were entered into the trial; 22 participated for eight weeks and 19 completed the study in terms of treadmill walking distance measurements at 12 weeks. The mean walking distance for all patients was increased 111% over baseline at week 12. Thirteen subjects were considered drug responders (greater than or equal to 50% increase in treadmill walking distance) and 9 were considered nonresponders (less than 50% increase). Improvements in clinical signs and symptoms of COAD were noted. Decreases in elevated systemic systolic pressures (but not diastolic) were unexpectedly observed in many drug responders. Seven of 19 males reported sexual function improvements while receiving pentoxifylline. Fourteen (58%) of the 24 subjects reported mild side effects of dyspepsia, nausea, vomiting, dizziness, headache, or insomnia; no subjects were withdrawn from the study because of side effects. In summary, pentoxifylline improved function and symptoms in 13 of 22 geriatric patients with intermittent claudication; the drug was safe and well tolerated at the usual dosage in this geriatric patient population.     

Pentoxifylline treatment of moderate to severe chronic occlusive arterial disease

A pilot study of the effects of pentoxifylline in 19 patients with moderate to severe chronic occlusive arterial disease (COAD) is described. The severity of disease was assessed by the degree of limitation in the walking distance on the flat surface (less than 100 m), the absence of peripheral pulses on palpation, the diminished Doppler tibial/brachial pressure (the ischemic index) at rest, and by contrast arteriography, when available. After a 2-week washout phase, all subjects received pentoxifylline (1200 mg/day) in an open-label manner for a total of 12 weeks. Twelve of the nineteen patients showed a definite increase in exercise tolerance by the end of the study, with a concomitant reduction in ischemic symptoms. All except 3 patients felt they had derived benefit from the medication. In contrast to the clear improvements in walking distance and symptoms, only small effects on noninvasive vascular laboratory measurements were noted. Platelet aggregation, induced by ADP, epinephrine, and collagen, gradually decreased over the study period. Pentoxifylline appears to be useful in the medical management of patients with moderate to severe chronic occlusive arterial disease; future controlled trials in such patients are now justified.     

A clinical safety trial of stroma-free hemoglobin

A stroma-free hemoglobin (SFH) solution was prepared which was sterile, pyrogen free, and contained only 1.2% of the stromal lipid present in unpurified hemolysate, 250 ml of which was administered slowly intravenously to 8 healthy men. Two control subjects received 250 ml of serum albumin. The SFH infusions were generally well tolerated by 7 of the 8 men. One subject developed abdominal pain and costovertebral angle tenderness after infusion, which disappeared within 48 hr. Bradycardia and a mild increase in blood pressure was present during ths SFH infusions and for 4 to 5 hr thereafter. A decrease in urine output and endogenous creatinine clearance appeared during the SFH infusions and for 2 to 4 hr after infusion. A mild prolongation of the activated partial thromboplastin time developed immediately after infusion. Gross hemoglobinuria appeared as expected during the SFH infusions and completely disappeared by 6 to 10 hr after infusion. All the cardiovascular, renal, and clotting changes were present for only a few hours after the SFH infusion, during the hemoglobinemia (free Hb in plasma). At 24 hr and 7 days after infusion all measurements were normal, and 6 mo follow-up showed no abnormalities or hepatitis.