The nitrogen mustard derivatives of 4-phenylbutyric acid and L-phenylalanine, called chlorambucil (Chl) and melphalan (Mel), respectively, have been incorporated into several peptide hormones, including luteinizing hormone-releasing hormone (LH-RH). The alkylating analogues of LH-RH were prepared by linking Chl, as an N-acyl moiety, to the complete amino acid sequence of agonistic and antagonistic analogues. These compounds, in particular the antagonistic analogues, showed much lower potency than their congeners carrying other acyl groups. To obtain highly potent alkylating analogues of LH-RH, the D enantiomer of Mel was incorporated into position 6 of the native hormone and some of its antagonistic analogues. Of the peptides prepared, [D-Mel6]LH-RH (SB-05) and [Ac-D-Nal(2)1,D-Phe(pCl)2,D-Pal(3)3,Arg5,D-Mel6,D-Ala10++ +]LH-RH [SB-86, where Nal(2) is 3-(2-naphthyl)alanine and Pal(3) is 3-(3-pyridyl)alanine] possessed the expected high agonistic and antagonistic activities, respectively, and also showed high affinities for the membrane receptors of rat pituitary cells, human breast cancer cells, human prostate cancer cells, and rat Dunning R-3327 prostate tumor cells. These two analogues exerted cytotoxic effects on human and rat mammary cancer cells in vitro. Thus these two D-Mel6 analogues seem to be particularly suitable for the study of how alkylating analogues of LH-RH could interfere with intracellular events in certain cancer cells.

Metal complexes related to the cytotoxic complexes cisplatin [cis-diamminedichloroplatinum(II)] and transbis(salicylaldoximato)copper(II) were incorporated into suitably modified luteinizing hormone-releasing hormone (LH-RH) analogues containing D-lysine at position 6. Some of the metallopeptides thus obtained proved to be highly active LH-RH agonists or antagonists. For instance, SB-40, a PtCl2-containing metallopeptide in which platinum is coordinated to an N epsilon-(DL-2,3-diaminopropionyl)-D-lysine residue [D-Lys(DL-A2pr] at position 6, showed 50 times higher LH-releasing potency than the native hormone. SB-95, [Ac-D-Nal(2)1,D-Phe(pCl)2, D-Pal(3)2, Arg5,D-Lys[DL-A2pr(Sal2Cu)]6,D-Ala10]LH-RH, where Nal(2) is 3-(2-naphthyl)alanine, Pal(3) is 3-(3-pyridyl)alanine, and copper(II) is coordinated to the salicylideneimino moieties resulting from condensation of salicylaldehyde with D-Lys(DL-A2pr)6, caused 100% inhibition of ovulation at a dose of 3 micrograms in rats. Most metallopeptide analogues of LH-RH showed high affinities for the membrane receptors of rat pituitary and human breast cancer cells. Some of these metallopeptides had cytotoxic activity against human breast cancer and prostate cancer cell lines in vitro (this will be the subject of a separate paper on cytotoxicity evaluation). Such cytostatic metallopeptides could be envisioned as targeted chemotherapeutic agents in cancers that contain receptors for LH-RH-like peptides.

Studies of intestinal hemodynamics during increased abdominal and intraluminal pressure in adult animals (canine and feline) have shown that blood flow is practically unchanged at pressures up to 35-40 mm Hg. In the young animal, however, decreased total intestinal blood flow has been shown at pressures of 15 mm Hg or greater. To help characterize the effect of intraluminal pressure on intestinal circulation, we have studied pressure-flow relationships in an isolated loop of terminal ileum in piglets 2-14 days of age (mean, 6.1 +/- 3.7 SD, n = 14) with a mean weight of 1,745 +/- 345 SD. Intraluminal pressure was increased from 0-50 cm of water pressure in 10-cm steps of two min' duration. Blood flow was reduced with every increase in intraluminal pressure and significantly reduced at pressures of 20 cm of water or more. The calculated peripheral vascular resistance increased with every increment of intraluminal pressure. Analysis of the relationship of arterial blood pressure to changes in blood flow suggests that blood flow reductions are greater in animals with lower blood pressure at every level of intraluminal pressure studied. Increased intraluminal pressure could be a mechanism of intestinal mucosal ischemia in the newborn, particularly affecting those with low arterial blood pressure.

Using sensitive multipoint micromethods, we estimated membrane receptors for [D‐Trp6]‐luteinizing hormone‐releasing hormone ([D‐Trp6]‐LH‐RH), somatostatin (SS‐14), human prolactin (hPRL), and epidermal growth factor (EGF) in experimental Dunning rat prostate cancers and in samples of normal human prostate, benign prostatic hyperplasia (BPH), and human prostate cancer (PC) obtained from biopsy, after prostatectomy, or at autopsy. In the Dunning R‐3327 rat prostate adenocarcinoma specimens, the receptors were characterized in untreated animals and following in vivo treatment with microcapsules of the agonist [D‐Trp6]‐LH‐RH and the somatostatin analog RC‐160. Two populations of binding sites were found for [D‐Trp6]‐LH‐RH, one with high affinity and low capacity and another with low affinity and high capacity. Treatment with [D‐Trp6]‐LH‐RH and RC‐160 alone or with the combination of these analogs increased the binding capacity (Bmax) of the low‐affinity binding sites for [D‐Trp6]‐LH‐RH and decreased Bmax for hPRL and EGF. Therapy with [D‐Trp6]‐LH‐RH also reduced Bmax of SS‐14 binding and dissociation binding constant of high‐affinity binding sites for [D‐Trp6]‐LH‐RH, whereas administration of RC‐160 or the combination treatment with both analogs increased Bmax of SS‐14 binding. These findings are compatible with the view that analogs of LH‐RH and SS‐14 might exert some direct inhibitory effects on the Dunning prostate cancer. Among 13 human BPH samples examined, only one had receptors for [D‐Trp6]‐LH‐RH, and seven specimens exhibited binding for prolactin. [D‐Trp6]‐LH‐RH receptors were found in all seven samples of human PC but not in any of the eight specimens of normal human prostate. All samples of normal human prostate, BPH, and human PC exhibited binding sites for EGF but not for SS‐14. Our findings on the membrane receptors in the human and rat prostate cancers raise the intriguing possibility that LH‐RH, acting as a growth factor, along with EGF and prolactin, might be involved in complex interactions that contribute to the promotion of prostate cancer in man.

In 1984 and 1985 a questionnaire was applied to 5611 railway transport workers in Croatia. Out of them, those satisfying the criteria of the Geneva Convention (1980) of the International Working Group for the Early Detection of Colorectal Carcinoma (3379) were supplied with the Hemdetect test. Of these 3379 workers, 2428 (71.8%) returned the "consumed" test after three days: in 114 of them the Hemdetect test was positive. Since in this way 5 patients with colorectal carcinoma (4.85%), 17 with polyps (16.5%), and 3 with polyposis (2.92%) were detected, it is maintained that the Hemdetect test is very useful, in fact unavoidable in attempts at the secondary prevention of colorectal carcinoma and the lesions proceeding it. Although the 34.95% of so-called false positive results obtained by the Hemdetect test diminish its significance because of a reduced specificity, it should not be excluded from practical work on the secondary prevention of colorectal carcinoma--it should in fact be put ahead of other tests, because it is simple, easily applied, readily acceptable by examinees, and less costly than the use of immunochemical methods.

In previous reports it was found that in mesenteric blood vessels exist profound alpha-adrenergic, and less profound beta-adrenergic receptors. Our experiments were done on 20 mongrel dogs, both sexes, weighing 6.5-22.5 kg, age from 1-2 years, which were divided into 2 groups: experimental (14 dogs) and control (6 dogs). Experimental group of animals passed through the posthemorrhagic hypotension (180 min. at 5.3 kPa). Aim of investigation was to clarify mesenteric vascular reactivity changes during posthemorrhagic hypotension. In order to reach this goal, phenylephrine and isoproterenol were injected alternatively in one hour intervals through cannulated superior mesenteric artery first proximal branch. Our results indicate that mesenteric blood flow responses to those drugs changed quantitatively, but never ceased. It is apparent from our experiments that those quantitative changes are due to beta 2 adrenoceptors changes during the posthemorrhagic hypotension.

Both verapamil and nifedipine were found to inhibit various types of activation of the isolated rat uterus, as for example: tonic and phasic components of contraction produced by KC1 and by oxytocin, phasic components of contraction produced by electrical stimulation and phasic spontaneous rhythmic activity. Presumably, verapamil and nifedipine affect a common pathway in calcium metabolism in all three types of muscle activation. Both verapamil and nifedipine inhibited more the contractile responses to high concentrations of KC1 than the responses to oxytocin, indicating the possibility of KCI and oxytocin acting through different calcium channels. Nifedipine inhibited more the tonic than phasic components of contractions produced by both KCI and oxytocin. It is assumed that two different calcium channels might be implicated in two components of contractions produced by KCI and oxytocin. Phasic components of contraction produced by KCI and by electrical stimulation were almost completely restored by increasing the concentration of calcium in the medium, whereas tonic components were restored only to about 50%.