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Biomedical subjects

M Suehiro

Publications and source records attributed to M Suehiro.

At least 37 records · Page 2Linked to original sources
PubMed1994

Circulating forms of immunoreactive parathyroid hormone-related protein for identifying patients with humoral hypercalcemia of malignancy: a comparative study with C-terminal(109-141)- and N-terminal(1-86)-region-specific PTHrP radioassay.

We evaluated the circulating forms of immunoreactive PTHrP in 115 healthy subjects and 122 patients with malignant diseases by using radioassay systems (RAS) specific for the C-terminal (109-141) fragment of PTHrP (C-RAS) and for the N-terminal(1-86) (N-RAS). PTHrP levels in healthy controls ranged from 1.5 to 38.2 (mean: 24.5) pmol/L with the C-RAS and from 0.9 to 2.5 (mean: 1.7) pmol/L with the N-RAS. The ratio of circulating N-terminal fragment (N) to C-terminal fragment (C) of PTHrP was calculated to be about 1: 14.4 in the healthy subjects. Of the 122 patients with malignant diseases, 40 (32.8%) had circulating PTHrP levels undetectable with the N-RAS, but only 11 (9.0%) patients had levels undetectable with the C-RAS. Of the former 122 patients, 41 (33.6%) had high PTHrP as determined with the C-RAS, and 10 (8.2%) had high PTHrP as determined with the N-RAS. The former of these included only 8 (19.5%) HHM patients, while the latter included 8 (80.0%) HHM patients. The circulating N to C ratio was about 1: 70.7 in the HHM patients. The N and C obtained with the different RASs showed a close correlation (r = 0.86). The values also showed a close correlation with serum Ca; r = 0.75 for C-RAS and r = 0.81 for N-RAS. In addition, the correlations between the PTHrP reading obtained with the different RASs and serum Cr were: r = 0.42 with C-RAS and r = 0.26 with N-RAS. The circulating form of immunoreactive PTHrP fragments is therefore comprised mainly of PTHrP(109-141). In contrast, circulating concentrations of the PTHrP(1-86) fragment are very low, but detection of the PTHrP(1-86) fragment with the N-RAS is a more useful indicator of HHM with fewer false positive results and is less likely to be influenced by renal function than the detection of the PTHrP(109-141) fragment with C-RAS.

Adolescent↗
PubMed1994

Highly potent indanamine serotonin uptake blockers as radiotracers for imaging serotonin uptake sites.

Two highly potent indanamine serotonin (5-HT) uptake blockers, trans-3'-(4'-bromophenyl)-1-indanamine (trans-[11C]DBPI or [11C]Lu 19-056) and its iodo analog, trans-3'(4'-[125I]iodophenyl)-1-indanamine (trans-[125I]DIPI) were evaluated as radiotracers for imaging 5-HT uptake sites in vivo Trans-[11C]DBPI was synthesized by N-methylation of the normethyl precursor with [11C]iodomethane. Trans-[125I]DIPI was synthesized by iododestannylation of the tributyltin precursor with [125I]NaI. Radiochemical yields for the [11C] and [125I] radiotracers were 34 and 40% with specific activities of 4000 and 1800 mCi/mumol, respectively. In vitro, the iodo analog, trans-DIPI, showed an IC50 value of 0.26 nM in inhibition of [3H]paroxetine binding to 5-HT uptake sites in rat cortex. The potency was found to be equivalent to that of paroxetine or McN5652. In vivo, after i.v. injection into mice, both radiotracers showed high uptake in brain (3-4% dose/whole brain at 15 min) and high accumulation into target tissues such as hypothalamus and olfactory tubercles (7-8% dose/g at 60 min). The binding was blocked by pre-injection of 5 mg/kg of peroxetine. While the in vivo distribution agreed with previously reported 5-HT uptake site distribution, the radiotracers showed high uptake in non-target tissues such as cerebellum, resulting in low target-to-non-target ratios (1.5-1.6 at 60 min). Since washout from non-target regions was slower than from target regions, longer-time observation with 125I up to 6 h did not improve the ratios. HPLC analyses of mouse brain homogenates and blocking studies indicated that the high uptake in non-target regions is not the result of metabolism or any interaction of the radiotracers with those tissues via specific binding sites. In spite of low target-to-non-target ratios, target regions with high density of 5-HT uptake sites, such as the raphe nuclei, superior colliculi and substantia nigra, were visualized with trans-[125I]DIPI by ex vivo autoradiography, since the radiotracer showed high specific binding (total mimus nonspecific binding).

Animals↗
PubMed1994

[Historical review on chemical and medical studies of globefish toxin before World War II].

"Fugu," a species of globefish has eaten by Japanese people for a long time, so globefish poisoning in Japan has been prevalent. Figures are shown in the Annual Food Poisoning Report collected and issued by health service authorities of Japanese Government since 1879. These reports prompted Dr. Yoshizumi Tahara, National Institute of Hygienic Sciences to conduct a chemical investigation of the toxic substance of globefish in 1884. However, the analysis was very difficult and his report of investigation was delayed. Before publication of the report of Dr. Tahara, pharmacological and toxicological studies of globefish poisoning were reported by three research groups from the Facultly of Medicine, University of Tokyo in 1889. These reports concluded that globefish poison has curare-like activity and its distribution was limited to specific organs such as the ovaries and the liver. Dr. Tahara successfully isolated the poison from aqueaous extract of ovaries of globefish by precipitation with lead acetate in the presence of ammonia. He presented the results at the monthly meeting of the Pharmaceutical Society of Japan in July 1894. He continued the studies and established an improved method for extraction and purification suitable for large-scale production. Finally, he confirmed that globefish contains only one toxic substance and named it Tetrodotoxin (TTX) in 1909. He elucidated the chemical nature of TTX as follows: 1) TTX is an amorphous hygroscopic powder and its character is neither alkaloid nor protein. 2) The possibility of TTX being a protamine was excluded by chemical analysis. Before the discovery ot TTX, according to folklore, globefish was regarded as medicine for leprosy because flesh of globefish contaminated with a sublethal dose of toxic substance alleviated the neuralgia of patients affected with leprosy. The clinical effect of TTX prepared by Tahara's method to suppress severe neuralgia due to leprosy and to reduce muscle spasms due to tetanus were reported by dermatologists in 1911. TTX was also given to patients with rheumatoid arthritis due to its analgesic effect. Thus, injectable TTX was manufactured and distributed by Sankyo Co., Ltd. from 1913. In terms of purity, the TTX preparation manufactured by Tahara's method seemed to be much more crude than the crystalline TTX obtained by Professor Tsuda and Dr. Kawamura in 1952. According to their report, the LD50 of the preparation for clinical use manufactured by Tahara's method was 4-5 mg/kg mouse compared to 4-6 microg/kg mouse of crystalline TTX.

Animals↗
PubMed1994

Development of PET/SPECT ligands for the serotonin transporter.

There is a great need for PET and SPECT ligands with high affinity and selectivity for the serotonin uptake site. These imaging agents would be useful in screening human populations at risk (e.g., individuals exposed to neurotoxic amphetamines such as MDMA and fenfluramine). Moreover, these radioligands would allow the study of serotonergic function in the normal living human brain, and they also would be useful in the examination of altered serotonergic neurotransmission in diseases such as depression and obsessive-compulsive and other neuropsychiatric disorders. Over the past several years, a number of radioligands have been studied in several laboratories for their in vivo binding to 5-HT uptake sites. Although [3H]paroxetine showed promising binding characteristics, conversion of authentic paroxetine into a PET or SPECT tracer turned out to be difficult and has not been achieved yet. Analogs of paroxetine displayed considerable loss of binding affinity and were, therefore, not useful for imaging purposes. For [11C]fluoxetine, [11C]citalopram, and cis-[11C]DDPI, target-to-nontarget (hypothalamus-to-cerebellar) ratios remained less than 2.0:1 over a 90-min period after injection. The most promising PET agents identified today are [11C]RTI-55 and [11C]McN-5652-X. [11C]RTI-55 labels both 5-HT and DA uptake sites. [11C]McN-5652-X is highly selective for 5-HT uptake sites, and its distribution is consistent with the neuroanatomical distribution of the 5-HT uptake site. Because [11C]McN-5652-Z is a racemic mixture of two stereoisomers, of which the (+) isomer (McN-5652-X) binds to the 5-HT uptake site in vivo and the (-) isomer (McN-5652-W) does not, the possibility exists that regional-specific binding can be determined by subtracting nonspecific binding of the (-) isomer from total radioactivity counts obtained with the (+) isomer. [11C]McN-5652-X is the best PET radioligand for the 5-HT uptake site described thus far. This tracer warrants further testing in nonhuman primates. Efforts are underway to obtain an investigational new drug application for use of the tracer in humans. Promising candidates as SPECT imaging agents for the 5-HT uptake site are [123I]RTI-55 and [123I]-iodo-6-nitroquipazine. Both agents are under intense investigation in different laboratories in the United States.

Animals↗
PubMed1993

[11C](+)McN5652 as a radiotracer for imaging serotonin uptake sites with PET.

The in vivo behavior of the stereoisomers of [11C]McN5652, a highly potent serotonin (5-HT) uptake blocker, was determined to evaluate their utility as radiotracers for imaging 5-HT uptake sites by positron emission tomography (PET). After intravenous injection into mice, [11C](+)McN5652 showed markedly higher uptake and longer retention in regions with high density of 5-HT uptake sites than the [11C]-labeled racemic mixture, while [11C](-)McN5652 washed out rapidly. With the [11C](+)-enantiomer, the ratio between hypothalamus and cerebellum reached 6 at 90 minutes. The binding of [11C](+)McN5652 was inhibited by 45-73% by pre-injection of 5 mg/kg of paroxetine, a selective 5-HT uptake blocker, in all regions examined except cerebellum where no significant effect of the drug was observed. [11C](-)McN5652 showed no specific binding in any of the regions. The [11C]-labeled cis isomer, [11C]McN5655, revealed surprisingly low brain penetration and showed no significantly higher uptake in regions of interest than cerebellum. These results suggest that [11C](+)McN5652 is a promising candidate as a PET radiotracer for studying 5-HT uptake sites in vivo.

Animals↗
PubMed1993

[Clinical utility of thallium-201 chloride in the diagnosis of parathyroid glands in patients with hyperparathyroidism].

Clinical utility for detection of hyperfunctioning parathyroid glands in patients with primary and secondary hyperparathyroidism (PHPT, SHPT) using 201TlCl and 99mTcO4-images was estimated in 50 patients including 18 PHPT and 32 SHPT (male; n = 31, female; n = 19, 51.5 +/- 11.1 yr). Detection of 94 hyperfunctioning parathyroid glands in 34 cases were achieved correctly by 201TlCl and 99mTcO4- images in agreement with surgical findings. Detectability of hyperfunctioning parathyroid glands was 100% in more than 1.0 g, 62.0% in more than 0.5 g and 41.5% in less than 0.5 g respectively. Ectopic parathyroid glands in two cases and a metastasis to pretracheal lymph node in one case were clearly demonstrated. Our results show that parathyroid scintigraphy using 201TlCl and 99mTcO4- as well as 131I or 123I is useful and safe method for preoperative detection of hyperfunctioning parathyroid glands.

Adult↗
PubMed1993

A PET radiotracer for studying serotonin uptake sites: carbon-11-McN-5652Z.

A radioligand for imaging central serotonin (5-hydroxytryptamine; 5-HT) uptake sites by positron emission tomography (PET) has yet to be developed. Such a tracer would be useful for the study of normal and altered serotonergic neurotransmission as well as for the detection of serotonergic neurotoxicity. This paper describes the labeling of the highly potent serotonin (5-HT) uptake blocker, McN-5652-Z (trans-1,2,3,5,6,10 beta-hexahydro-6-[4-(methylthio)phenyl]pyrrolo-[2,1-a]-isoquinoline; racemic mixture), with 11C and the evaluation of this radiotracer in rodents with respect to its in vivo binding characteristics. In mouse brain, 11C-McN-5652-Z accumulated rapidly in regions with high densities of 5-HT uptake sites. The ratio between hypothalamus and cerebellum was 1.5:1 at 15 min and increased with time to 4.6:1 at 90 min after injection. The distribution of 11C-McN-5652 in rat brain at 60 min correlated well with regional concentrations of 5-HT uptake sites (r = 0.86). The specificity and selectivity of 11C-McN-5652 binding to the 5-HT transporter were tested by preinjecting blocking doses of known 5-HT, dopamine and norepinephrine uptake inhibitors, and a 5-HT2 receptor blocker before injection of the radiotracer. Preinjection of increasing doses of unlabeled McN-5652-Z inhibited 11C-McN-5652-Z binding in a dose-dependent fashion. These results suggest that the in vivo binding of the radiotracer was specific, selective for 5-HT uptake sites, saturable and that 11C-McN-5652-Z holds promise as a radiotracer for PET imaging of 5-HT uptake sites in the mammalian brain.

Animals↗
PubMed1992

Myocardial uptake of antimyosin antibody compared with serum myosin light chain I levels in patients with myocardial infarction.

Myocardial accumulation of In-111-antimyosin (InAM) was evaluated in comparison with circulating serum myosin light chain I (LCI) level at the time of InAM injection. Seventeen consecutive patients were studied at various stages ranging from 6 days to 34 days after myocardial infarction (MI). The infarct area was positive for InAM uptake in all patients (100%), and significant myocardial uptake was observed in 14 patients (82.4%). The intensity of InAM uptake correlated with the infarct location shown by ECG and CAG. In contrast, 12 patients (70.6%) had normal or undetectable serum myosin LCI levels, with 5 being normal (0.42-2.5 ng/ml) and 7 undetectable (0.42 ng/ml or less). Only 5 patients (29.4%) had elevated serum myosin LCI levels at the time of InAM injection, and this elevation was slight, ranging from 3.4 to 4.5 ng/ml (mean: 3.75 ng/ml). Among patients with undetectable, normal, and elevated serum myosin LCI levels, there was no significant correlation between InAM uptake and the serum myosin LCI level. Thus, even after the serum myosin LCI level has decreased to normal, InAM can still bind to cardiac myosin in patients with MI, presumably until there is complete recovery from the hibernating myocardium due to ischemic damage.

Adult↗
PubMed1992

Serum thymidine kinase, a possible marker for monitoring the effect of bone marrow transplant treatment in early recovery phase.

We measured serum thymidine kinase (TK) activity with a radioenzyme assay system employing [I-125]-iododeoxyuridine as the tracer on serial specimens from five bone marrow transplant (BMT) patients before and after transplantation. The serum level of TK activity in the 4 patients with effective BMT treatment ranged from 3.0 to 16.9 U/L (mean, 7.80 U/L) before transplantation and from 27.3 to 236.1 U/L (mean, 82.95 U/L) after the BMT treatment. Mean serum TK activity increased 13.17-fold (range, 1.68 to 29.14-fold). In contrast, the activity in the patient with ineffective BMT treatment was not significantly different during, before, or after BMT treatment. In addition, serum TK activity in BMT patients was well correlated with the change in the number of leukocytes before and after BMT treatment [r = +0.709 (p less than 0.01), y = 0.012 x +0.87]. We conclude that the determination of serum TK activity in BMT patients is very useful in monitoring the course of bone marrow transplantation in the early recovery phase.

Adolescent↗
PubMed1992

Localization of hyperfunctioning parathyroid glands by means of thallium-201 and iodine-131 subtraction scintigraphy in patients with primary and secondary hyperparathyroidism.

The accuracy of the preoperative localization of hyperfunctioning parathyroid glands by subtraction scintigraphy with 201Tl and 131I was evaluated by comparison with the operative findings. The subjects were 67 consecutive patients with hyperparathyroidism (HPT), including 24 with primary and 43 with secondary HPT. In primary HPT, surgery revealed 26 adenomas weighing 0.26-15.80 g (mean +/- SD; 3.01 +/- 3.04 g). Two patients had double adenomas. Scintigraphy correctly localized 25/26 adenomas (96.2%) in primary HPT for a sensitivity, specificity, and accuracy of 96.2%, 98.5%, and 97.9%, respectively. In secondary HPT, 163 hyperplastic glands weighing 0.03-5.08 g (0.85 +/- 0.93 g) were found. Scintigraphy correctly localized 79 glands (48.5%) weighing 0.03-5.08 g (1.19 +/- 1.10 g), but 84 glands (51.5%) weighing 0.04-2.70 g (0.51 +/- 0.50 g) were not detected. Thus, the sensitivity, specificity, and accuracy of scintigraphy were respectively 48.5%, 100%, and 51.2%, in secondary HPT. These results show that scintigraphy with 201Tl and 131I can be used to locate abnormal parathyroid glands with an efficacy equal to or better than that of the conventional methods with 201Tl and 99mTc or 201Tl and 123I.

Adenoma↗
PubMed1992

Synthesis and biodistribution of a new radiotracer for in vivo labeling of serotonin uptake sites by PET, cis-N,N-[11C]dimethyl-3-(2',4'-dichlorophenyl)-indanamine (cis-[11C]DDPI).

A new PET radiotracer for in vivo labeling of serotonin (5-HT) uptake sites, cis-N,N-[11C]dimethyl-3-(2',4'-dichlorophenyl)-indanamine, cis-[11C]DDPI, was synthesized and its biological behavior was studied. The radiosynthesis of cis-[11C]DDPI was performed by N-methylation of cis-N-methyl-3-(2',4'-dichlorophenyl)-indanamine with [11C]iodomethane. The average radiochemical yield was approx. 8%, with an average specific activity of 600 mCi/mumol. Following intravenous administration, cis-[11C]DDPI accumulated in mouse brain regions rich in 5-HT uptake sites, such as olfactory tubercles, hypothalamus and frontal cortex. Following pre-injection of 1 mg/kg of paroxetine, a high affinity 5-HT uptake blocker, the binding of cis-[11C]DDPI in the olfactory tubercles, hypothalamus and frontal cortex was decreased by 23, 25 and 16%; this corresponds to 73, 82 and 59% of the specific binding in these regions. These results suggest that the accumulation of cis-[11C]DDPI in the tissues rich in 5-HT sites is a result of specific binding of cis-[11C]DDPI to 5-HT uptake sites. Due to the relatively high non-specific uptake and slow clearance of this compound from non-specific binding sites, the ratio between specific and non-specific binding increased slowly with time, reaching 1.5:1 at 60 min after injection.

Animals↗
PubMed1992

[Historical review of insulin and its preparations in pharmacopoeia (3). Fish insulins].

Existence of encapsulated glands situated in the mesentery of certain teleosti was reported by Brockmann (1846) and Stannius (1848), respectively. Thus the gland was named stannius corpuscle or Brockmann body. Later, as results of histological study, cells of stannius corpuscle tissues were constituted with Langerhans islet cells observed in mammalian pancreas by Diammare (1899) and Laguesse (1906). Thus, before the days of discovery of insulin by Banting and Best in 1921, stannius corpuscle has been interesting from the aspects of comparative anatomy and physiology. Rennie (1906) examined a large number of specimens in various species of teleosti and gave the term "principal islet" to easily recognizable stannius corpuscle. Osawa studied comparative anatomy in Freiburg and returned to Tokyo. He continued the study of comparative anatomy of Langerhans islet aand published a report on observation of "principal islet" of flatfish, limanda yokohamae Gth. in 1912 in Japanese. His report seemed to be a milestone of studies of fish insulin in Japan. Macleod attempted to demonstrate direct evidence on secretion of insulin from Langerhans islet cells. Experiments were made on extraction of "principal islet" of teleosti, angler Lophius) and sculpin (Myoxocephalus) to obtain insulin and demonstrated activity. No insulin activity was obtained from pancreatic tissues constituted with acinar cells of these fishes. In the case of elasmobranch, Langerhans islets are not separated, but potent insulin could be extracted from the pancreas. His report published in 1922 was the first report on fish insulin. Succeeding to Macleod's report, several reports on fish insulin were contnributed from Canada, England and U.S.A. until 1929. Dr. Kkumagai, Professor of Internal Medicine, Tohoku Imperial University (Sendai) also conducted the studies on extraction of active principle of pancreas since 1920, independently. But, a Toronto group reached the goal on discovery of insulin earlier than the Sendai group. The Sendai group also described extraction of active principle from the "principal islet" of teleosti. Especially, Ukai (1926) described morphological study on pancreas and stannius corpuscle for more than twenty species of fish. His report played an important role as the next milestone on the road of fish insulin development studies in Japan. In 1926, Dr. Sakaguchi who was a leading clinical diabetologist in Japan published a monograph entitled "Insulin" written in Japanese. He referred the report on fish insulins of McCormick and Noble and Dr. Kumagai's report, however, he commented that production of insulin from fish seemed to be less worthy due to requirements of laborious work to collect small stannius corpuscle from fish. Professor A. Ogata described a textbook entitled "Zoki-Yakuhin-Kagaku (chemistry of organotherapeutics): in 1931. In the first edition, papers of Macleod, McCormick, Dudley and Osawa were referred. In the revised fifth edition (1940) contained description of unpublished data of insulin content of various kinds of fish caught in Japan and supplied from his student Nagasawa. Under the circumstance of expanding tendency of the China Incident to World War II, shortage of importation and production of insulin preparations manufactured from domestic animals was anticipated. Development on manufacture of fish insulin became urgent. [Truncated]

Animals↗
PubMed1992

[Fundamental evaluation of ELSA.F-beta HCG kit as an immunoradiometric assay specific for serum beta HCG].

We evaluated ELSA.F-beta HCG kit as an immunoradiometric assay (IRMA) specific for serum beta human chorionic gonadotropin (beta hCG). This IRMA was found to be highly sensitive to serum beta hCG; the minimum detectable concentration of beta hCG was 0.05 ng/ml. No significant effects on the standard curves were observed when first and second incubation time and temperature were varied from 30 min to 240 min and from 4 degrees C to 37 degrees C, respectively. Commercial LH, FSH, and TSH had little effect on the assay system; the cross-reactivity of commercial hCG was 2.5%, and 0.14% after unconjugated beta hCG with alpha-subunit was absorbed with ELSA-tube. Multiple dilutions of sera of pregnancy resulted in curves paralleling that obtained using standard beta hCG; the recovery of beta hCG added to the serum was 98.1 +/- 2.5% (mean +/- SD), and mean coefficient of variation of the interassay reproducibility of serum beta hCG (n = 10) was 6.7 +/- 2.8 (SD)%. Serum beta hCG concentration measured using ELSA.F-beta HCG kit was well correlated with that measured using conventional beta hCG RIA kit (r = +0.961, p less than 0.01), although values were lower than those measured with the latter (y = 0.35x + 0.26). Our results suggest that ELSA.F-beta HCG kit is a useful assay system for serum beta hCG.

Chorionic Gonadotropin↗
PubMed1991

Detection of bile leakage into the thoracic cavity by hepatobiliary scintigraphy.

We report early detection of bile leakage into the thoracic cavity by hepatobiliary scintigraphy in a rare case of spontaneous withdrawal of the catheter for percutaneous transhepatic cholangiographic drainage (PTCD). An 81-year-old man with inoperable carcinoma of the common bile duct was readmitted with a 38 degrees C fever and suspected bile leakage from the hepatic biliary tree following withdrawal of the catheter for PTCD. While plain X-ray immediately after readmission revealed no abnormality in the chest or abdomen, hepatobiliary scintigraphy revealed not only bile leakage into the right thoracic cavity but also the site of laceration. We conclude that hepatobiliary scintigraphy is a simple, non-invasive procedure useful in the early detection and localization of bile leakage following spontaneous withdrawal of the catheter for PTCD.

Aged↗
PubMed1991

Radiosynthesis and evaluation of N-(3-[18F]fluoropropyl)paroxetine as a radiotracer for in vivo labeling of serotonin uptake sites by PET.

To visualize serotonin uptake sites by positron emission tomography (PET), N-(3-[18F]fluoropropyl)-paroxetine ([18F]FPP), a derivative of the selective serotonin uptake blocker paroxetine, was synthesized from 3-[18F]fluoropropyltosylate and paroxetine via a one-pot procedure. The rate of formation of [18F]FPP was a function of the ratio of the initial amount of paroxetine to that of 1,3-propanediol bistosylate with which [18F]fluoropropyltosylate was synthesized. When the reaction mixture contained an excess amount of paroxetine over that of the propyl-bistosylate, the radiosynthesis followed by HPLC purification, which took approx. 90 min, gave [18F]FPP in a radiochemical yield of approx. 8%, and in high radiochemical and chemical purity. The specific activity was 2640 +/- 360 mCi/mumol. The brain biodistribution of [18F]FPP showed no distinguishable localization in regions with high density of serotonin uptake sites such as hypothalamus or olfactory tubercles. In vitro binding assays revealed that N-fluoropropylation of paroxetine reduced the affinity for the serotonin uptake site by three orders of magnitude.

Animals↗
PubMed1990

Bromination, no-carrier-added radiobromination and simultaneously-occurring chlorination by chloramine T.

Factors regulating initial rates of bromination, no-carrier-added radiobromination and simultaneously-occurring chlorination by chloramine T were studied using a neuroleptic drug spiperone as the substrate. Besides the factors such as initial concentrations of chloramine T, substrate and bromide ions, upon which the rates were dependent in first, second or zero-order, the water-acetic acid composition or the hydrogen ion concentration of the solutions, where the reactions took place, was found to play a key role. By controlling these factors, optimal radiobromination conditions, where radiobromination proceeds effectively whilst simultaneously-occurring chlorination is kept from proceeding at a high rate, thus resulting in radiobrominated radiopharmaceuticals of high specific activity (10 Ci/mumol) and high radiochemical and chemical purity, could be fulfilled.

Bromine↗