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Biomedical subjects

W Graham

Publications and source records attributed to W Graham.

At least 19 recordsLinked to original sources
PubMed1999

Enhancement of fluid filtration across tumor vessels: implication for delivery of macromolecules.

Cancer therapies using genes and other macromolecules might realize their full clinical potential if they could be delivered to tumor tissue in optimal quantities. Unfortunately, the compromised circulation within tumors poses a formidable resistance to adequate and uniform penetration of these agents. Previously, we have proposed elevated interstitial fluid pressure (IFP) as a major physiological barrier to delivery of macromolecules. Here we postulate that modulation of tumor microvascular pressure (MVP) and associated changes in IFP would enhance macromolecular delivery into a solid tumor. To test our hypothesis, we altered tumor MVP by either periodic injection or continuous infusion of angiotensin II (AII) and measured the resulting changes in IFP and uptake of macromolecules. We used the nicotinyl hydrazine derivative of human polyclonal IgG (HYNIC-IgG) as a nonspecific macromolecule and CC49 antibody as a specific macromolecule. We found that both chronic and periodic modulation of tumor MVP enhances transvascular fluid filtration, leading to a 40% increase in total uptake of the specific antibody within 4 hr of its administration. Conversely, neither continuous nor periodic infusion of AII induced any increase in uptake of nonspecific antibodies. Strategies to improve delivery of macromolecules and limitations of this approach are identified.

Animals↗
PubMed1998

Safe motherhood.

Explore the source record for details and available documents.

Female↗
PubMed1998

Rapid detection of Parkinson's disease by SPECT with altropane: a selective ligand for dopamine transporters.

Increasing evidence indicates that dopamine (DA) transporter density declines in Parkinson's disease (PD). 2Beta-carbomethoxy-3beta-(4-fluorophenyl)-n-(1-iodoprop-1-en -3-yl) nortropane (IACFT, Altropane) is a cocaine analog with high affinity and selectivity for dopamine transporter (DAT) sites in the striatum. In this study, single photon emission computed tomography (SPECT) with [123I]altropane was used to measure DAT density in seven healthy volunteers (five males, age 37-75, and two females, ages 26 and 39) and eight male patients with Parkinson's disease (age 14-79, Hoehn and Yahr stage: 1.5-3 (n = 5) and 4-5 (n = 3)). Dynamic SPECT images and arterial blood samples were acquired over 1.5-2 hr and plasma radioactivity was analyzed chromatographically to obtain metabolite corrected arterial input functions. Binding potential (BP, B'max/KD) for striatal (Str) DAT sites was calculated by two methods using occipital cortex (Occ) as a reference. In the first method, tissue time-activity curves (TAC) and metabolite corrected arterial input functions were analyzed by a linear graphical method developed for reversible receptor ligands. In the second method, the expression (Str(TAC) - Occ(TAC)) was fitted to a gamma variate function and the maximum divided by Occ(TAC) at the same time was used to estimate BP. In five of the PD patients, the SPECT data were compared with the results of PET with [18F] 6-fluoro DOPA (FD-PET). Plasma analysis indicated that [123I]altropane is rapidly converted to polar metabolites. SPECT images in healthy volunteers showed that [123I] altropane accumulated rapidly and selectively in the striatum and yielded excellent quality images within 1 h after injection. Both methods of analysis revealed a 7.6%/decade reduction in BP and average striatal values (corrected to age 25) were 1.83 +/- 0.22 and 2.09 +/- 0.20 by methods 1 and 2. In all the PD patients, striatal accumulation was markedly reduced and the pattern of loss was similar to that reported for DA; most profound in the posterior putamen with relative sparing of the caudate nuclei. A comparable pattern was observed with FD-PET. For total striatum, age-corrected BP was significantly (P < 0.001) reduced; 0.83 +/- 0.06 (method 1), 0.84 +/- 0.07 (method 2). BPs measured by the two methods were remarkably similar and highly correlated r2 = 0.88, (P < 0.001). These results indicate that [123I]altropane is an excellent SPECT ligand for imaging the DAT/DA neurons in human brain. The high selectivity and rapid striatal accumulation of the ligand allows for accurate quantitation of DAT sites in less than 2 hr. The results further demonstrate that [123I]altropane is an effective marker for PD.

Adolescent↗
PubMed1997

Effect of adrenergic receptor ligands on metaiodobenzylguanidine uptake and storage in neuroblastoma cells.

The effects of adrenergic receptor ligands on uptake and storage of the radiopharmaceutical [125I]metaiodobenzylguanidine (MIBG) were studied in the human neuroblastoma cell line SK-N-SH. For uptake studies, cells were incubated for 15 min with varying concentrations of alpha-agonist (clonidine, methoxamine, and xylazine), alpha-antagonist (phentolamine, tolazoline, phenoxybenzamine, yohimbine, and prazosin), beta-antagonist (propranolol, atenolol), beta-agonist (isoprenaline and salbutamol), mixed alpha/beta antagonist (labetalol), or the neuronal blocking agent guanethidine, prior to the addition of [125I]MIBG (0.1 microM). The incubation was continued for 2 h and specific cell-associated radioactivity was measured. For the storage studies, cells were incubated with [125I]MIBG for 2 h, followed by replacement with fresh medium with or without drug (MIBG, clonidine, or yohimbine). Cell-associated radioactivity was measured at various times over the next 20 h. Propanolol reduced [125I]MIBG uptake by approximately 30% (P<0.01) at all concentrations tested, most likely due to nonspecific membrane changes. However, incubation with the other beta-agonists or antagonists failed to elicit significant reductions in uptake. In contrast, all of the alpha-agonists significantly inhibited uptake (P<0.05); guanethidine >xylazine >clonidine=methoxamine. The alpha-antagonists demonstrated a broad range of inhibition (phenoxybenzamine >>phentolamine >prazosin >>yohimbine=tolazoline)(P< 0.05). The mixed ligand, labetolol, inhibited MIBG uptake in a dose-dependent manner with an apparent IC50 of 0.65 microM. The retention studies demonstrated that unlabeled MIBG caused profound self-inhibition (P<0.01). Clonidine produced a modest inhibition of retention and yohimbine had no effect. Labetalol, phenoxybenzamine, guanethidine, and propranolol reduced uptake of [125I]MIBG by neuroblastoma cells in culture. Although only labetalol has been reported to cause false-negative MIBG scans, our results suggest that these other drugs have the potential to interfere with MIBG imaging and therapy, particularly at high doses. Adrenergic drugs did not alter cytoplasmic retention of [125I]MIBG in neuroblastoma cells but may have potential in tumors such as phenochromocytoma, where granular storage of MIBG has been observed. Inhibition of [125I]MIBG retention by unlabeled MIBG supports the use of high specific activity radioiodinated MIBG for both diagnosis and therapy.

3-Iodobenzylguanidine↗
PubMed1997

Asking questions about women's reproductive health: validity and reliability of survey findings from Istanbul.

In countries where population-based data on health problems are scarce, the extent of reproductive morbidity can be estimated from replies in structured interviews as a complement or as an alternative to reports from physician's examination and laboratory tests. We examined the sensitivity and specificity of detected morbidity based on these replies as compared to medical diagnoses and explored the consistency of replies when the questionnaire was administered twice, by two types of interviewers in different environments. Data were collected in a cross-sectional survey in Istanbul. The presence or absence of five morbidities, reproductive and urinary tract infections (RTI and UTI), menstrual disorders, pelvic relaxation and anaemia was determined by algorithms based on the replies, and by the physician's diagnosis. Except with anaemia, questionnaire replies were more specific than sensitive in detecting morbidity, probably partly due to many morbid conditions being accepted as normal. Sepcificity exceeded 80% for home reports of menstrual disorders (93.0%), pelvic relaxation (95.7%), RTI (abnormal discharge and pain) (81.2%) and UTI (80.7%), with the corresponding figure for anaemia at 41.7%; the best sensitivity results were for anaemia (58.3%), RTI (abnormal discharge only) (49.3%) and menstrual disorders (45.4%) with figures for pelvic relaxation and UTI reaching only 17.3 and 13.0%. Reliability between the interviews (assessed by the K coefficient), was highest at 66.1% for pelvic relaxation and lowest at 39.9% for menstrual disorders. Reliability varied between the two lay interviewers, suggesting the interviewer and the interview conditions are important. Questionnaire-based information on this type of morbidity is most useful for ascertaining perceived ill-health and only of limited use for the corresponding medically defined conditions.

Adult↗
PubMed1997

Insulin-like growth factor I receptor messenger RNA in the colon is unchanged during neoplasia.

The expression of growth factor receptor messenger RNA is difficult to quantitate due to low copy number. We describe a quantitative polymerase chain reaction that rapidly, reproducibly assays expression of human insulin-like growth factor I (IGF-I) receptor mRNA from small, biopsy-sized, specimens of tissue. This was then clinically applied to surgically resected specimens of colon. Total RNA was isolated from normal colonic mucosa and documented tumors from 4 patients undergoing resection. The mRNA was first reverse-transcribed with an oligomer bearing a complementary sequence specific for the mRNA at its 3' end, and a sequence complementary to an intervening intron of the IGF-I receptor gene at the 5' end. Competitive PCR was then performed in the presence of the cDNA product and exogenously added genomic DNA, with an upstream primer complementary to the exon sequence of the gene of interest and a downstream primer complementary to the intron sequence that was tagged to the cDNA. The genomic DNA was used as the internal standard. To calculate the number of copies of mRNA per microgram total RNA, a standard curve was used. No difference was noted in IGF-I receptor expression between neoplastic and normal colonic mucosa. This quantitative PCR is accurate, rapid, and requires very small amounts of tissue. Potential uses are in determining genetic expression of growth factor receptors or putative tumor markers preoperatively from small samples obtained during diagnostic colonoscopy or from samples obtained at surgery.

Colon↗
PubMed1997

Contraceptive choice and reproductive morbidity in Istanbul.

A cross-sectional survey was conducted in Istanbul to investigate the relationship between contraceptive choice and reproductive morbidity. Altogether, 918 women who had ever used any means of avoiding pregnancy were interviewed at home, and, among these, 694 parous nonpregnant women were examined by three female physicians. The women were aware of bearing a considerable burden of ill health, with 81 percent reporting at least one episode of illness in the three months prior to the interview. Current users of the intrauterine device were significantly more likely than users of other methods to report menstrual disorders, but pelvic relaxation and reproductive and urinary tract infections, whether perceived or diagnosed, were not significantly related to any of the contraceptive methods. The relatively small amount of switching between methods suggests that most users tended to stay with the same method once chosen and that health concerns played an important part only in the initial choice of the method.

Adolescent↗
PubMed1997

Localization of radiolabeled chemotactic peptide at focal sites of Escherichia coli infection in rabbits: evidence for a receptor-specific mechanism.

UNLABELLED: The infection imaging properties of a high-affinity 99mTc-labeled chemotactic peptide receptor agonist (N-formyl-methionyl-leucyl-phenylalanine-lysine; N-For-MLFK) were compared with a low-affinity agonist (N-Acetyl-MLFK; N-Ac-MLFK), a moderate-affinity antagonist (N-isobutyloxycarbonyl-MLFK; N-IBoc-MLFK) and non-specific inflammation imaging agents. METHODS: All peptides were prepared by solid-phase methods and purified by high-performance liquid chromatography. The products were assayed in vitro for N-formyl-methionyl-leucyl-phenylalanine receptor binding and superoxide production. Three types of studies were performed in rabbits with Escherichia coli infection: (Study A) Four groups of six animals were coinjected with 99mTc-N-For-MLFK-hydrazinonicotinamide (N-For-MLFK-HYNIC) plus 111In-immunoglobulin G, 111In-red blood cells or 111In-diethylene triamine pentaacetic acid. (Study B) Three groups of six rabbits were coinjected with 111In-leukocytes plus 99mTc-N-For-MLFK-HYNIC, 99mTc-N-Ac-MLFK-HYNIC or 99mTc-N-IBoc-MLFK-HYNIC. (Study C) Two groups of six rabbits were injected with 99mTc-N-For-MLFK-HYNIC and 111In-leukocytes with and without an excess of antagonist. In all three studies, the radiopharmaceuticals were injected 24 hr after infection and dual photon (99mTc and 111In) gamma camera images were acquired at 2-3 and 16-18 hr later. Target-to-background (T/B) ratios were calculated for regions of interest drawn over the infected and contralateral normal tissue. RESULTS: N-For-MLFK, N-Ac-MLFK and N-IBoc-MLFK had EC50s for receptor binding of 2.0, 830 and 150 nM, respectively. The corresponding EC50s for superoxide production were 20.0, approximately 10(3) and > 10(4). Study A demonstrated that the T/B for 99mTc-N-For-MLFK-HYNIC was higher than for any of the nonspecific imaging agents (p < 0.001), and 111In-immunoglobulin G had a higher T/B ratio than 111In-diethylenetriamine pentaacetic acid (p < 0.01) or 111In-red blood cells (p = NS). Study B showed that 99mTc-N-For-MLFK-HYNIC had a higher T/B ratio than the other peptides (p < 0.001). 111In-leukocytes and 99mTc-N-IBoc-MLFK-HYNIC had comparable T/B ratios, which were higher than for 99mTc-N-Ac-MLFK-HYNIC (p < 0.05). Study C demonstrated that coinjection with an antagonist resulted in a significant reduction in the T/B ratio for 99mTc-N-For-MLFK-HYNIC (p < 0.001), but did not affect the T/B ratio for 111In-leukocytes. CONCLUSION: Nonspecific mechanisms contribute minimally to the localization of 99mTc-chemotactic peptide analogs at sites of infection and the majority of the accumulation appears to be receptor mediated. Also, chemotactic peptide receptor antagonists can be used for infection imaging. These results provide important new insights for future radiopharmaceutical development.

Animals↗
PubMed1996

Applying the sisterhood method for estimating maternal mortality to a health facility-based sample: a comparison with results from a household-based sample.

BACKGROUND: The sisterhood method is an indirect technique used to estimate maternal mortality in developing countries, where maternal deaths are often poorly registered in official statistics. It has been used successfully in many community-based household surveys. Because such surveys can be costly, this study investigated the suitability of using data collected in outpatient health facilities. METHODS: Adults visiting any one of 91 health centres or posts in a rural region of Nicaragua were randomly sampled and interviewed by health personnel. A sample size, proportional to the population served, was assigned to each facility and 9232 adults were interviewed. Characteristics of health facility users were compared with the general population to identify factors that would allow generalization of results to other settings. RESULTS: Based on these data, the lifetime risk of maternal death was 0.0144 (1 in 69). This estimate is essentially identical to that from a household-based survey in the same region 8 months earlier, which obtained a lifetime risk of 0.0145 (1 in 69). These findings correspond to a maternal mortality ratio of 241 and 243/100000 livebirths, respectively. CONCLUSIONS: This is the first report comparing results of the sisterhood method from household and health facility-based samples. The sisterhood method provided a robust estimate of the magnitude of maternal mortality. Results from the opportunistic health facility-based sample were virtually identical to results from the household-based study. Guidelines need to be developed for applying this low-cost and efficient aproach to estimating maternal mortality in suitable opportunistic settings at subnational levels.

Adolescent↗
PubMed1995

Competitive reverse-transcriptase polymerase chain reaction without an artificial internal standard.

Advances in our understanding of molecular and cellular physiology necessitate that mRNA levels for specific growth factors and other rare transcripts be measured quantitatively in small samples. Conventional methods such as Northern blot analysis and solution hybridization/ribonuclease protection are not sufficiently sensitive. We now report the theory, development, and validation of a rapid and highly sensitive assay, the RNA/DNA quantitative polymerase chain reaction (RD-PCR), which uses a competitive PCR approach to measure the number of copies of a specific mRNA per cell. Total nucleic acid (RNA and genomic DNA) is isolated from cells in culture. The mRNA of interest is first reverse-transcribed with an oligomer bearing a complementary sequence specific for the mRNA at its 3'-end, and a sequence complementary to an intron of the desired gene at the 5'-end. Competitive PCR is then performed in the presence of the cDNA product and endogenous genomic DNA, with an upstream primer complementary to the exon sequence of the gene of interest, and a downstream primer complementary to the intron sequence that was tagged to the cDNA. The cell's own genomic DNA is thereby used as the internal standard. To control for the efficiency of reverse transcription, a standard curve is used in each assay. The technique was validated by comparing the quantitation of insulin-like growth factor I (IGF-I) mRNA in two human cell lines by RD-PCR and by RNase protection analysis. Both methods gave similar numbers of copies of IGF-I mRNA per cell. For accurate analysis, RNase protection required at least 10(7) cells; RD-PCR required as little as 10(2) cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1995

Comparison of the infection imaging properties of a 99mTc labeled chemotactic peptide with 111In IgG.

The biodistribution and infection imaging properties of a 99mTc labeled hydrazino nicotinamide (HYNIC) derivatized chemotactic peptide analog (For-Met-Leu-Phe-Lys-HYNIC) and 111In-DTPA-IgG were compared in rabbits with Escherichia coli infection. Six New Zealand white rabbits were injected in the left posterior thigh with a suspension of E. coli. Twenty four hours later, the animals were injected with: 1.0 mCi of 99mTc labeled peptide plus 0.1 mCi of 111In-DTPA-IgG. At 2-3 and 16-18 h, dual photon scintigrams were acquired and the images were corrected for crossover between the two windows. After recording the final images, the animals were sacrificed and biodistribution was determined. At both imaging times the biodistributions of the two reagents were markedly different. The highest concentrations of 111In-DTPA-IgG were detected in blood pool structures, liver and kidney. In contrast localization of 99mTc labeled peptide was greatest in spleen, lung and liver (consistent with binding to leukocytes). In general, the sites of infection were better visualized with the radiolabeled peptide and T/B ratios increased with time (P < 0.01). At both times, the T/Bs for 99mTc-peptide were higher (P < 0.01); 3.54 +/- 0.47 vs 2.52 +/- 0.38 at 2-3 h and 6.88 +/- 0.79 vs 3.78 +/- 0.36 at 16-18 h. These results indicate that although both radiopharmaceuticals localize at sites of infection, the radiolabeled peptide are superior reagents for the rapid detection of focal sites of infection. However, since the mechanisms of localization are different the combined use of both agents could have value in the general evaluation of infection/inflammation.

Amino Acid Sequence↗
PubMed1995

Detection of acute bacterial infection within soft tissue injuries using a 99mTc-labeled chemotactic peptide.

OBJECTIVE: Infection imaging with a 99mTc-labeled chemotactic peptide was evaluated in a rabbit model of Escherichia coli infections in burned tissue. MATERIALS AND METHODS: The peptide was radiolabeled with 99mTc via the hydrazino nicotinamide derivative. Three groups of six animals were studied: (group A) unilateral infected burns; (group B) bilateral burns with unilateral infection; and (group C) uninfected burns. Twenty-four hours after injury, groups A and B were infected, and 8 hours later, all animals were injected with approximately 0.50 mCi of 99mTc-peptide. MEASUREMENTS AND MAIN RESULTS: In groups A and B, excellent images of the infections were obtained at 3 to 4 and 16 to 18 hours after injection of the peptide. At 3 to 4 hours after injection, the target-to-background ratios (T/B) were 3.12 +/- 0.28 for group A and 4.33 +/- 0.61 for group B (p = n.s.). At 16 to 18 hours, the T/B ratios increased significantly (p < 0.01): group A = 8.10 +/- 1.03 and B = 7.70 +/- 1.25. The T/B ratio for group C was only slightly greater than unity. CONCLUSIONS: These results indicate that 99mTc-labeled chemotactic peptides are effective radiopharmaceuticals for the rapid detection of focal sites of infection within thermally injured tissues.

Animals↗
PubMed1993

Technetium-99m-labeled hydrazino nicotinamide derivatized chemotactic peptide analogs for imaging focal sites of bacterial infection.

We synthesized and evaluated four hydrazino nicotinamide (HYNIC) derivatized chemotactic peptide analogs: For-NleLFK-HYNIC (HP1), For-MLFK-HYNIC (HP2), For-MLFNH(CH2)6NH-HYNIC (HP3), and For-MLF-(D)-K-HYNIC (HP4), for in vitro bioactivity and receptor binding. The peptides were radiolabeled with 99mTc via a glucoheptonate co-ligand and their biodistribution determined in rats (n = 6/time point) at 5, 30, 60 and 120 min after injection. Localization of the peptides at sites of deep thigh Escherichia coli infection was determined by radioactivity measurements on excised tissues in rats (n = 6/time point) and rabbits as well as scintillation camera imaging in rabbits (n = 6). All peptides maintained biological activity (EC50s for O2 production by human PMNs: 12-500 nM) and the ability to bind to the oligopeptide chemoattractant receptor on human PMNs (EC50s for binding: 0.12-40 nM). After incubation with 99mTc-glucoheptonate, radiolabeled peptides were isolated by HPLC at specific activities of > 10,000 mCi/microM. Technetium-99m-labeled peptides retained receptor binding with EC50s < 10 nM. Blood clearance of all four peptides was rapid. Biodistributions of the individual peptides were similar, with low levels of accumulation in most normal tissues. In rats, all of the peptides concentrated at the infection sites (T/B ratio: 2.5-3:1) within 1 hr of injection. In rabbits, outstanding images of the infection sites were obtained, with T/B ratios of > 20:1 at 15 hr after injection. This study demonstrates that 99mTc-labeled chemotactic peptide analogs are effective agents for the external imaging of focal sites of infection.

Animals↗
PubMed1993

Localization of indium-111-immunoglobulin G, technetium-99m-immunoglobulin G and indium-111-labeled white blood cells at sites of acute bacterial infection in rabbits.

Biodistribution and infection imaging properties of 111In-DTPA-IgG, 99mTc-hydrazino nicotinamide-IgG and 111In-WBC were compared in rabbits with E. coli infection. Groups of six rabbits were injected with 10 mCi of 99mTc-IgG plus 0.5 mCi of 111In-IgG or 1 mCi of 99mTc-IgG plus 0.05 mCi of 111In-WBC. At 4-5 and 18-20 hr, dual photon scintigrams were acquired. At both times, the distributions of 99mTc and 111In-IgG were nearly identical. The sites of infection were well visualized with all three radiopharmaceuticals. In the early images, the target-to-background ratios (T/B) for 111In and 99mTc-IgG determined by ROI analysis were 1.95 +/- 0.26 and 2.57 +/- 0.38 (p = NS). In the delayed images, the T/B ratios increased (p < 0.01) to 3.56 +/- 0.49 and 4.90 +/- 0.98. At both times, the T/B ratios for 111In-WBC were higher (p < 0.01); 4.17 +/- 0.78 at 4-5 hr and 8.52 +/- 1.52 at 18-20 hr. These results indicate that all three agents yield excellent images of infection sites. Although 111In-WBC had higher T/B ratios, the ease of preparation of the radiolabeled proteins makes them attractive alternatives for infection imaging.

Acute Disease↗
PubMed1993

Technetium-99m-labeled chemotactic peptides: comparison with indium-111-labeled white blood cells for localizing acute bacterial infection in the rabbit.

The biodistribution and infection imaging properties of 99mTc-labeled formyl-methionyl-leucyl-phenylalanyl-lysyl-hydrazinonicotinamide (99mTc-HP) were compared with 111In-labeled leukocytes (111In-WBCs) in rabbits with E. coli infections. Groups of six animals were co-injected with 1 mCi of 99mTc-HP plus 0.05 mCi of 111In-WBCs and serial scintigrams were acquired from 3 to 6 hr and 18 hr postinjection. After acquiring the final images, the animals were killed and biodistribution was determined. At all imaging times, the distributions of 99mTc-HP and 111In-WBCs were similar and the sites of infection were well visualized with both radiopharmaceuticals. The target (infected muscle) to background (contralateral normal muscle) ratios (T/B) were: 3.38 +/- 0.46, 3.80 +/- 0.37 and 10.87 +/- 1.44 for 99mTc-HP and 1.71 +/- 0.04, 1.81 +/- 0.26 and 3.79 +/- 0.83, for 111In-WBCs at 3, 6 and 18 hr postinjection, respectively. The average ratio of T/B ratios (99mTc-HP-to-111In-WBCs) was 2.99 +/- 1.88, with no value less than unity. T/B ratios calculated from direct tissue sampling were significantly higher for 99mTc-HP than for 111In-WBCs (33.6:1 versus 8.1:1, p < 0.01). These differences were primarily due to increased absolute accumulation of 99mTc-HP (0.102%ID/g versus 0.024%ID/g, p < 0.01) in infected muscle rather than a difference in accumulation in normal skeletal muscle. These results indicate that 99mTc-HP yields target-to-background ratios greater than or equal to those achievable with 111In-WBCs probably as a result of an increase in absolute accumulation at the site of infection.

Acute Disease↗