Short-term ocular tolerability of dorzolamide 2% and brinzolamide 1% vs placebo in primary open-angle glaucoma and ocular hypertension subjects.

PURPOSE: To compare ocular tolerability of dorzolamide 2%, brinzolamide 1%, and placebo given three times daily. METHODS: A prospective, double-masked, three-centre, crossover comparison in which 25 ocular hypertensive or primary-open angle glaucoma subjects were randomized to receive dorzolamide, brinzolamide, or placebo three times daily for 3 days. Intraocular pressure, visual acuity, a visual analogue scale, and ocular and systemic symptom queries were completed at the end of each period. RESULTS: After chronic dosing, there was a significant difference in ocular pain on the visual analogue scale among the groups at the 10-s postinstillation time point with dorzolamide having the highest level (22.5+/-28.9) compared to brinzolamide (5.0+/-8.7) or placebo (3.2+/-10.4) (P=0.0006). No differences between groups were observed preinstillation nor following dosing at 3 or 10-min postinstillation. On the initial instillation, the 10-s postinstillation pain was rated as 43.3+/-77.1, which was significantly higher than after chronic dosing (P=0.017). On the ocular symptom query, dorzolamide had the highest incidence of burning/stinging and redness compared to the other groups, but was generally characterized as mild. There were no significant differences in the visual acuity at any time point. CONCLUSIONS: This study suggests that subjects treated with dorzolamide suffer more ocular pain upon instillation compared to brinzolamide or placebo. However, pain symptoms are fewer following chronic dosing and are generally characterized as mild.

Effect of timolol 0.5% gel and solution on pulmonary function in older glaucoma patients.

PURPOSE: To evaluate the effect of timolol maleate solution or gel forming solution versus placebo on pulmonary function in patients with primary open-angle glaucoma or ocular hypertension without reactive airway disease. METHODS: After a screening visit, each patient was randomized by a Latin square technique to receive placebo twice daily, 0.5% timolol solution twice daily, or 0.5% timolol gel once a day (placebo given as second dose) to each eye for 2 weeks. Subjects then were crossed over to the two other treatments for 2-week treatment intervals. At each visit, patients were received a dose 15 minutes before pulmonary function testing. RESULTS: This study began with 25 patients, and 20 finished the trial. There was no difference between treatment groups for the forced expiratory volume at one second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio (P > 0.1). The mean FEV1 for timolol solution, timolol gel, and placebo was 2.42 L, 2.45 L, and 2.50 L, respectively. The mean FVC for timolol solution, timolol gel, and placebo was 3.33 L, 3.38 L, and 3.44 L, respectively. No difference in intraocular pressure was observed between the timolol solution (17.1 +/- 3.3 mm Hg) and timolol gel (17.1 +/- 3.6 mm Hg) between the treatment periods (P > 0.1). No difference in side effects was observed between treatment groups (P > 0.05). CONCLUSIONS: In older patients with primary open-angle glaucoma or ocular hypertension without reactive airway disease, nonselective beta-blockers should not worsen pulmonary function.

Brimonidine 0.2% given two or three times daily versus timolol maleate 0.5% in primary open-angle glaucoma.

PURPOSE: To evaluate the efficacy and safety of brimonidine 0.2% two or three times daily versus timolol maleate 0.5% solution twice daily. METHODS: Patients with primary open-angle glaucoma were randomized by Latin square technique to one of the three treatment sequences in this crossover, prospective double-masked trial. Each treatment period consisted of 6 weeks of chronic dosing followed by a diurnal curve for the intraocular pressure measured at 08:00, 10:00, 16:00, 18:00, 20:00, 22:00, and 24:00 hours. Intraocular pressure was measured by applanation tonometry. RESULTS: Thirty patients completed this trial. The average diurnal intraocular pressures in the trial were measured for timolol maleate (17.7 +/- 2.7 mm Hg), brimonidine given three times daily (18.0 +/- 2.2 mm Hg), and brimonidine given twice daily (19.2 +/- 2.4 mm Hg). There was a statistical difference between groups (P <.005). When groups were compared by pairs, three times daily dosing with brimonidine and timolol maleate both reduced the pressure more than twice daily brimonidine at every time point past 10:00 hours and for the diurnal curve (P <.05). In contrast, three times daily brimonidine and timolol maleate were statistically similar for the diurnal pressure, and each time point, except timolol maleate, decreased the pressure more at 16:00 (P =.042). Safety was similar between groups. CONCLUSIONS: This study demonstrated that both timolol maleate twice daily and brimonidine three times daily provide a similar intraocular pressure reduction to each other. Timolol maleate twice daily and brimonidine three times daily provide a greater decrease in pressure in the late afternoon and nighttime hours, compared with brimonidine twice daily.

Washout periods for brimonidine 0.2% and latanoprost 0.005%.

PURPOSE: To evaluate the intraocular pressure washout time after discontinuing brimonidine 0.2% twice daily and latanoprost 0.005% once every evening. METHODS: We discontinued brimonidine or latanoprost in a masked fashion from primary open-angle glaucoma or ocular hypertensive patients. The intraocular pressure was measured twice weekly until patients returned to untreated baseline. RESULTS: In 32 patients, the mean longest eye washout time for brimonidine (n = 15) was 3.3 +/- 3.0 weeks and for latanoprost (n = 17) was 4.4 +/- 3.2 weeks (P =.24). In all but one patient, brimonidine returned to baseline by 5 weeks and latanoprost returned by 8 weeks. CONCLUSION: After discontinuing latanoprost or brimonidine, a wide variation exists in washout times among individuals, with latanoprost demonstrating a trend to a longer washout period.

Twenty-four hour intraocular pressure reduction with latanoprost compared with pilocarpine as third-line therapy in exfoliation glaucoma.

PURPOSE: To compare the 24 hour efficacy of latanoprost 0.005% given every evening with that of pilocarpine 4% given four times daily as third-line therapy in patients with exfoliation glaucoma receiving timolol 0.5% and dorzolamide 2% each given twice daily. METHOD: We enrolled 30 patients with exfoliation glaucoma not adequately controlled on timolol maleate 0.5% and dorzolamide 2%. Each patient underwent a baseline 24 hour intraocular pressure curve testing at 06:00, 10:00, 14:00, 18:00, 22:00 and 02:00 hours. Patients were randomised to receive either latanoprost 0.005% or pilocarpine 4% for a minimum of 8 weeks and were then crossed over to the opposite therapy. Diurnal curve testing was repeated at the end of each treatment. RESULTS: There was a significant decrease from baseline in intraocular pressure at each timepoint for both study medicines (p < 0.016). Latanoprost provided better intraocular pressure control than pilocarpine at daytime measuresments (17.4 vs 19.7 mmHg at 06:00 hours, p < 0.001; 17.8 vs 19.1 mmHg at 10:00 hours, p = 0.04). However, pilocarpine reduced the pressure more than latanoprost at 22:00 hours (18.4 vs 19.5 mmHg, p = 0.016). Overall, the diurnal intraocular pressure was reduced from a baseline of 21.5 +/- 3.7 mmHg to 18.8 +/- 3.1 mmHg on pilocarpine and to 18.0 +/- 3.0 mmHg on latanoprost (p = 0.06). In addition, mean peak pressure was similar between pilocarpine (21.0 +/- 2.9 mmHg) and latanoprost (20.5 +/- 3.8 mmHg) (p = 0.20). Side-effects were similar with the exception of blurred vision, which was only found with pilocarpine (10%). Compliance was more difficult with pilocarpine. CONCLUSION: In exfoliation glaucoma, as a third-line adjunctive therapy added to timolol and dorzolamide, latanoprost and pilocarpine have similar diurnal efficacy. However, latanoprost provides a greater morning pressure reduction.

Additive efficacy of unoprostone isopropyl 0.12% (rescula) to latanoprost 0.005%.

PURPOSE: To evaluate the safety and efficacy of adding unoprostone isopropyl 0.12% vs placebo both given twice daily to latanoprost 0.005% given every evening. METHODS: We treated 41 patients with primary open-angle glaucoma or ocular hypertension with latanoprost 0.005% for 1 month and then randomized each to either placebo or unoprostone isopropyl 0.12% for 8 weeks. Diurnal intraocular pressures were measured at 08:00, 10:00, 12:00, 18:00, and 20:00 hours, both at baseline (time of randomization) and after 8 weeks of treatment. RESULTS: Twenty patients were treated in the placebo group and 21 in the unoprostone isopropyl group. After 8 weeks of treatment in the placebo group, the trough intraocular pressure at 08:00 and the diurnal pressure were 20.4 +/- 3.2 and 19.1 +/- 2.2 mm Hg, respectively. In the unoprostone isopropyl group the pressures were 19.4 +/- 3.3 and 18.0 +/- 1.7 mm Hg (P =.22 and P =.042), respectively. However, eyes with a baseline pressure of 22 mm Hg or greater on latanoprost had an average 3.3 mm Hg greater reduction at trough (P <.01) and a 2.1 mm Hg greater decrease in diurnal pressure (P =.030) after adding unoprostone isopropyl (n = 14 eyes) compared with placebo (n = 16 eyes; P <.001). In addition, the range of the pressures throughout the diurnal curve was reduced from 2.7 mm Hg on latanoprost alone to 1.4 mm Hg after adding unoprostone isopropyl. Adverse events were similar between groups, and no patients were discontinued because of safety reasons. CONCLUSIONS: This study suggests that unoprostone isopropyl can safely improve the diurnal curve characteristics in patients who continue to have an elevated pressure on latanoprost 0.005% alone.

Differences in ocular surface irritation between timolol hemihydrate and timolol maleate.

PURPOSE: We evaluated the anterior segment surface reaction findings between timolol hemihydrate and timolol maleate. The only known difference between these preparations is the maleate salt. METHODS: After a baseline examination, we randomized 28 healthy subjects (26 completed) to timolol hemihydrate or timolol maleate given in both eyes twice daily, in a double masked fashion, for 1 week. Subjects then were evaluated at the morning trough (hour 0 examination), dosed, and re-evaluated in 1 hour (hour 1 examination). Subjects were left untreated for 1 week and then switched to the opposite medication for the second study period. RESULTS: Corneal staining (graded 0 to 4) for timolol maleate was worse between baseline (0.9) and hour 0 (1.4; P =.009) and baseline and hour 1 (1.4; P =.011). Also, mean punctate corneal staining for timolol maleate was increased from baseline (22.6) to hour 0 (31.7; P =.033) and showed borderline significance to hour 1 (33.4; P =.058), and for timolol hemihydrate there was a borderline significant elevation from baseline (24.2) to hour 1 (29.8; P =.060). When treatment groups were compared, there was a greater change in corneal staining with timolol maleate than timolol hemihydrate from baseline to hour 0 (P =.020) and greater staining with timolol maleate than timolol hemihydrate at hour 0 (P =.032). Nasal conjunctiva showed increased mean staining with timolol maleate from baseline (23.6, P =.035) to hour 0 (29.5, P =.035) and to hour 1 (31.9 P =.038) but not with timolol hemihydrate. There were increased symptoms of ocular dryness from baseline to hour 0 with timolol maleate (P =.012) but not with timolol hemihydrate. CONCLUSIONS: The study suggests that timolol maleate potentially may have more of an irritant effect than timolol hemihydrate on the corneal and nasal conjunctival epithelium.

Factors associated with long-term progression or stability in primary open-angle glaucoma.

PURPOSE: To evaluate long-term risk factors for progression or stability in patients with primary open-angle glaucoma. METHOD: We retrospectively included consecutively reviewed patients who had primary open-angle glaucoma for at least 5 years in this multicenter trial. Historical and clinical factors in these patients were evaluated for their association with stability or progression of the glaucoma. RESULTS: We included 218 patients in this study; of these, 34 progressed over an average length of follow-up of 45.5 +/- 30.0 months, and 184 were stable over an average of 72.8 +/- 18.3 months. The mean intraocular pressure over the follow-up period for the progressed group was 19.5 +/- 3.8 mm Hg and for the stable group 17. 2 +/- 3.1 mm Hg (P =.001). The average standard deviation of individual intraocular pressures was greater in the progressed group (5.1 mm Hg) than the stable group (3.9 mm Hg, P =.012). Baseline characteristics indicating a greater potential to progress were a larger cup-to-disk ratio (P <.001), a greater number of medications (P =.02), older age (P.007), and worse visual acuity (P =.003). However, no difference was observed in pressure levels that prevented progression in these subpopulations compared with the total sample size. CONCLUSIONS: This study suggests that lowering the intraocular pressure is important in the treatment of primary open-angle glaucoma to help prevent long-term progression. Lowering the pressure, however, is not uniformly effective in preventing progression. Additionally, risk factors for progression do not further help identify pressure levels that prevent worsening of glaucoma.

Brimonidine 0.2% versus dorzolamide 2% each given three times daily to reduce intraocular pressure.

PURPOSE: To evaluate the efficacy and safety of brimonidine compared with dorzolamide given three times daily as monotherapy in patients with primary open-angle glaucoma or ocular hypertension. METHODS: In a double-masked, multicenter, crossover comparison in 40 patients, qualified patients were washed out from their previous medication and randomized to dorzolamide 2% or brimonidine 0.2% for the first 6-week treatment period. Patients then were washed out for 2 weeks and started on the opposite medication for the second 6-week period. RESULTS: Baseline intraocular pressure for all 40 subjects (76 eyes) was 24.1 +/- 2.0 mm Hg. This study found that the 8:00 AM trough intraocular pressure after 6 weeks of therapy for dorzolamide was 20. 7 +/- 3.1 mm Hg and for brimonidine 20.8 +/- 3.2 mm Hg (P =.99). The peak intraocular pressure (2 hours after dosing) for dorzolamide was 18.6 +/- 3.4 mm Hg and for brimonidine 17.8 +/- 2.7 mm Hg (P =.10 ). Dorzolamide caused more stinging upon instillation (P <.01) and brimonidine more itching (P =.01). No statistical differences existed between groups for systemic adverse events. Six patients, all on brimonidine, were discontinued from a treatment period early. Of these, two were discontinued for inadequate pressure control, two with dizziness and fatigue, one with ocular pain, and one for lifestyle reasons (P =.07). CONCLUSIONS: This study found similar efficacy and safety between monotherapy treatment with dorzolamide or brimonidine when each was given three times daily to patients with ocular hypertension or primary open-angle glaucoma.

Comparison of the efficacy and safety of latanoprost 0.005% compared to brimonidine 0.2% or dorzolamide 2% when added to a topical beta-adrenergic blocker in patients with primary open-angle glaucoma or ocular hypertension.

The purpose of this study was to evaluate the ocular hypotensive efficacy and safety of latanoprost 0.005% (Xalatan, Pharmacia & Upjohn), brimonidine (Alphagan, Allergan), and dorzolamide (Trusopt, Merck Inc.) when added to a beta-blocker in patients with ocular hypertension or primary open-angle glaucoma. This was a multicenter, retrospective analysis which included all reviewed patient records in which latanoprost, brimonidine or dorzolamide were added to a beta-blocker for at least three months. Patients who were treated for less than three months, who failed therapy due to ineffectiveness of the medicine or an adverse event also were included. The study included 141 patients. Latanoprost (n = 50) showed an intraocular pressure of 16.7 +/- 3.3 mm Hg (-6.3 +/- 4.1 mm Hg, P < 0.001), brimonidine (n = 24) 17.4 +/- 4.9 mm Hg (-4.2 +/- 4.5 mm Hg, P < 0.001), and dorzolamide (n = 67) 20.1 +/- 6.1 mm Hg (-3.1 +/- 5.1 mm Hg, P < 0.001) at three months. A significant difference was observed in the absolute level of intraocular pressure (P < 0.005) and the change from baseline between groups (P < 0.005) at three months. A significant difference was observed between groups in the success rate of therapy between latanoprost (70%), brimonidine (58%) and dorzolamide (40%) (P = 0.008). No significant differences were observed between groups for rate or type of adverse events leading to discontinued therapy. This study showed that latanoprost, when added to beta-blockers, compares favorably in ocular hypotensive efficacy and is similar in safety to brimonidine and dorzolamide.

Therapeutic success of latanoprost 0.005% compared to brimonidine 0.2% in patients with open-angle glaucoma or ocular hypertension.

The purpose of this study was to evaluate the success rate ofmonotherapy with latanoprost 0.005% once daily versus brimonidine 0.2% twice daily in patients with open-angle glaucoma or ocular hypertension. Patients who were prescribed latanoprost or brimonidine as monotherapy were included in this study, and their consecutive charts were retrospectively reviewed. The primary efficacy variable was success of therapy, defined as a reduction in intraocular pressure > or =3 mm Hg without an adverse event leading to discontinuation over a potential of six months of therapy. We included 157 patients in this study. In the latanoprost group, 64 of 92 (70%) were considered successes; 26 of 65 (40%) were successful with brimonidine (P < 0.001). Nine failed brimonidine therapy, and one latanoprost, because of an adverse event, and the rest failed because of inadequate intraocular pressure response. The change from baseline in intraocular pressure was significantly greater with latanoprost (mean +/- S.D., 21.6 +/- 5.1 to 17.1 +/- 3.3 mm Hg) than brimonidine (23.7 +/- 5.6 to 21.9 +/- 5.7 mm Hg) (P = 0.001). Overall, 52 (80%) brimonidine- and 41 (45%) latanoprost-treated patients required additional visit(s) to adjust therapy to further lower intraocular pressure or to assess an adverse event (P < 0.001). In conclusion, latanoprost more likely provides a successful response to therapy than brimonidine when used as monotherapy in primary open-angle glaucoma or ocular hypertensive patients.

Efficacy and safety of timolol solution once daily vs timolol gel added to latanoprost.

PURPOSE: To compare the efficacy and safety of timolol hemihydrate 0.5% (Betimol, Ciba Vision Ophthalmics, Duluth, Georgia) vs timolol maleate gel-forming solution 0.5% (Timoptic-XE, Merck, Blue Bell, Pennsylvania), both given every morning added to latanoprost 0.005% given every evening. METHODS: A multicenter, randomized, crossover comparison was performed in patients with primary open-angle glaucoma or ocular hypertension. After at least a 4-week run-in period with latanoprost 0.005% (Xalatan, Pharmacia & Upjohn, Kalamazoo, Michigan), both eyes from 30 patients (60 eyes) were randomly assigned to one of the two adjunctive therapies, timolol hemihydrate or timolol maleate gel for 6 weeks. At the end of the first period, the study medicine was discontinued for a 2-week washout period. Patients then received the opposite medication for the second 6-week period. This study had an 80% power to exclude a 1-mm Hg difference between groups. RESULTS: The baseline intraocular pressure after 1 month of latanoprost treatment only for all 30 subjects was 20.8 +/- 2.6 mm Hg. After 6 weeks of timolol hemihydrate, the 24-hour trough intraocular pressure was 17.5 +/- 3.4 mm Hg, and for timolol maleate gel, 17.9 +/- 3.5 mm Hg (P = .74). The peak level 2 hours after dosing for timolol hemihydate was 16.4 +/- 2.6 mm Hg, and for timolol maleate gel, 16.8 +/- 3.8 mm Hg (P = .84). No patient was discontinued from the study because of lack of efficacy. No differences were observed between treatments in visual acuity, anterior segment findings, or adverse events. CONCLUSIONS: Once-daily beta-blocker therapy is an effective ocular hypotensive adjunctive treatment 24 hours after dosing when added to latanoprost, for which timolol hemihydrate 0.5% solution and timolol maleate gel 0.5% appear equally effective and safe.

1H magnetic resonance spectroscopy of primary human and murine cells of the myeloid lineage.

Murine and human cells of the myeloid lineage can exhibit proton spectra arising primarily from neutral lipid such as triglyceride, similar to other activated and transformed cell types. These spectral characteristics are independent of proliferation or proliferative ability and can be induced in vivo and in vitro in murine peritoneal macrophages by Listeria and interferon-gamma stimulation, respectively. In human peripheral monocytes, this spectrum can develop in the apparent absence of external activating stimuli such as interferon or endotoxin and also occurs in the absence of proliferation. Furthermore, 16-h culture of mixed peripheral blood cells causes concomitant and similar spectral changes in lymphocytes, which do not occur in pure lymphocyte cultures. The lipid spectra induced in mixed cultures develop to the same extent regardless of cell density or the ability to adhere or form aggregates and regardless of whether serum supplementation is of fetal bovine or adult human origin. Unlike peritoneal macrophages, the addition of interferon-gamma causes no additional spectral changes in adherent or nonadherent cultures. However, reduction of serum concentrations in culture medium causes a dose-dependent decrease in the acquired lipid signal. The observed spectral differences between human and murine myeloid populations could be species-dependent but could also be due to their differentiation status.

Magnetic resonance studies of murine macrophages. Proliferation is not a prerequisite for acquisition of an 'activated' high resolution spectrum.

Proton magnetic resonance spectroscopy (1H-MRS) was used to investigate the membranes of macrophages activated by gamma-interferon in vitro and by Listeria monocytogenes in vivo. We report the appearance with activation, of a high resolution spectrum indistinguishable from that found in activated T and B cells and embryonic and malignant cell types previously studied. We furthermore show that proliferation is not a prerequisite for the appearance of this activated spectrum. This supports the idea that membrane 'activation' in all cells, irrespective of origin, may be accompanied by similar architectural changes, and suggests that a common pathway exists for the activation of cell membranes of the immune system, possibly important in the acquisition of increased motility. The use of 1H-MRS as a non-invasive tool for analysis of activation is discussed.

Tumour evolution in rats monitored by changes to serum and lipoproteins.

The biochemical, physicochemical and magnetic resonance (MR) properties of rat serum allow tumour evolution to be monitored. Serum from female Fischer rats injected with rat mammary adenocarcinoma cells contained a low-density lipoprotein (LDL)-like lipoprotein and decreased high-density lipoprotein levels compared with normal rat serum. Increases in secondary tumour burden coincided with enlarged LDL-like particles, altered MR properties and elevation of serum triglyceride. By fucosidase treating metastatic R13762 cells prior to injection, not only was metastatic capacity retarded, but serum lipoproteins were also altered. These physicochemical alterations suggest an intricate relationship between both primary and secondary tumour burdens and the serum lipoprotein profile.

Development of the "activated" high resolution 1H MR spectrum in murine T cells and B cells occurs in G1 phase of the cell cycle.

T and B lymphocytes stimulated with mitogens develop 1H MR spectra characteristic of triglycerides in an isotropic environment. These distinctive signals, which are also observed in malignant cells, cannot be suppressed by compounds which inhibit progression through the cell cycle. Cellular proliferation is thus not essential for the development and maintenance of high resolution lipid spectra in activated cells.

Uterine cervical punch biopsy specimens can be analyzed by 1H MRS.

Biopsy specimens of the uterine cervix, including colposcopically directed punch biopsy specimens of females with atypical Papanicolaou smear tests, are suitable for analysis by magnetic resonance (MR) spectroscopy. A narrow lined lipid MR spectrum, characteristic of malignant tissue, is obtained from a 6-mm3 biopsy specimen of histologically confirmed squamous carcinoma of the cervix. In contrast, specimens containing inflammatory cells generate a broad component only centered at 1.3 ppm with a T2 relaxation value of less than 350 ms. Most biopsy specimens which contain dysplastic cells or evidence of human papilloma virus (HPV) infection have a discernible lipid spectrum similar to that of the malignant tissue specimen. Long T2 relaxation values found in malignant tissue specimens at 1.3 and 1.2 ppm are observed in some but not all of the biopsies which show evidence of HPV infection. The suitability of small tissue samples, such as punch biopsy specimens, for study by MR illustrates the sensitivity of this technique and its potential as an aid to histopathological discrimination between the various precursor states of cervical cancer.

Further evidence that the narrow 1H magnetic resonance signals from malignant cells do not arise from intracellular lipid droplets.

1H magnetic resonance (MR) spectroscopy of intact viable malignant cells yields high resolution spectra from lipid. In previous studies we have provided evidence that these signals are generated by neutral lipid located in the plasma membrane in unique domains. We show that intracellular lipid droplets do not contribute to the MR signal. Two malignant Chinese hamster ovary cell lines, EOT and its parental line WT were studied. The EOT cells have a more highly resolved lipid spectrum than the WT, a result which correlates with slightly increased levels of triglyceride in highly purified plasma membranes. The intracellular lipid droplets of both lines were quantified using both fluorescence and electron microscopy but no significant differences were observed. Together these results provide evidence that narrow 1H MR signals from malignant cells arise from neutral lipid in the plasma membrane, rather than from intracellular lipid droplets.

Vinblastine sensitivity of leukaemic lymphoblasts modulated by serum lipid.

The high-resolution proton magnetic resonance spectrum of leukaemic lymphoblasts is characteristic of neutral lipid in an isotropic environment. When such lymphoblasts are selected for resistance to the anticancer drug vinblastine, the intensity of this spectrum increases with increasing drug resistance. A reversal of this trend can be achieved by growing cells in delipidated serum, whereby lipid spectrum and drug resistance are diminished. However, both can be restored by subsequent regrowth in normal medium. Thus, although detectable genetic changes accompany the development of vinblastine resistance, the expression of these changes can be modulated by environmental lipid.

Application of a T2-filtered COSY experiment to identify the origin of slowly relaxing species in normal and malignant tissue.

The 1H NMR spectrum of whole cells consists of many overlapping resonances which are difficult to resolve into individual components. We have developed a modification of the COSY pulse sequence which filters out resonances on the basis of their T2 relaxation rate. When applied to malignant cells, this technique has helped to identify fucose as the origin of the slowly relaxing species associated with their metastatic capacity. The technique can also be used to obtain T2 relaxation rates for individual resonances in a broad envelope of lines.