Prodrugs of Peptides. 9. Bioreversible N-α-Hydroxyalkylation of the Peptide Bond to Effect Protection Against Carboxypeptidase or Other Proteolytic Enzymes

Various N--hydroxyalkyl derivatives of N-acyl amino acids and di- and tripeptides were prepared by hydrolysis or aminolysis of N-acyl 5-oxazolidinones. The stability of these derivatives was studied in aqueous solution as a function of pH. The compounds were all degraded quantitatively to their parent N-acylated amino acid or peptide and aldehyde but with vastly different rates. At pH 7.4 and 37°C the half-lives of decomposition ranged from 4 min to 1500 hr. The structural factors influencing the stability included both steric and polar effects within the acyl and N--hydroxyalkyl moieties as well as within the amino acid attached to the N--hydroxyalkylated N-acyl amino acid. Whereas the N-benzyloxycarbonyl (Z) derivatives of the dipeptides Gly-L-Leu and Gly-L-Ala were readily hydrolyzed by carboxypeptidase A, the N-hydroxymethylated compounds, i.e., Z-Gly(CH₂OH)-Leu and Z-Gly(CH₂OH)-Ala, were resistant to cleavage by the enzyme as revealed by their similar rates of decomposition in the presence or absence of the enzyme at pH 7.4 and 37°C. The results suggest that N--hydroxyalkylation of a peptide bond protects not only this bond but also an adjacent peptide bond against proteolytic cleavage. Since the N--hydroxyalkyl derivatives are readily bioreversible, undergoing spontaneous hydrolysis at physiological pH, this prodrug approach promises to overcome the enzymatic barrier to absorption of various peptides.     

Facial pain

Summary In a prospective material of 1052 patients the precipitating factors, associated symptoms, psychological and neurological deficits have been examined.Mastication and talking are the most frequently occurring precipitating factors, 76% as regards Neuralgia, with typical starting difficulties. As regards Non-neuralgiform Pain 24%, with precipitation late in the masticatory process. There were trigger zones in 50% of the cases of Typical Trigeminal Neuralgia and in 9% of the patients with Non-neuralgiform Pain. In a series of cases the jaw joint is perceived as a trigger zone. Cold precipitates pain in 48%–39%. Other precipitating factors are much more rare-psychological stress in 15% of the patients with Non-neuralgiform Pain, however.Vegetative associated symptoms were relatively frequent, lacrimation occurred in 31% of the cases of Typical Trigeminal Neuralgia and in 20% of the cases of Non-neuralgiform Pain. Rhinorrhea and salivation were less frequent. In terms of figures migrainoid associated symptoms had no connection with vegetative associated symptoms or with pain in the eye.In 11 % of the patients pain occurred most frequently during the night and in 20% the frequency of pain was the same day and night. About 1/3 of the patients with Neuralgia experienced seasonal variations.Tenderness of foramina is a symptom of no significance. Very few patients had primary sensory loss. No eye or ear symptoms have been found which may be referred to as the patho-anatomical basis of the pain.About 1/3 of the patients with Non-neuralgiform Pain had psychological symptoms whereas hardly any patients with Neuralgia had them. MMPI test performed on a small matched material showed no difference between Neuralgia and Non-neuralgiform Pain.In material B an examination has been made of the jaw joint arthrosis symptoms. A restriction of the diagnosis of arthrosis has had the effect that it must be recognized that patients with facial pain do not have the high frequency of jaw joint diseases previously assumed. As was also the case in a series of normal material previously published, between 1/5 and 1/3 of the patients with Neuralgia had jaw joint arthrosis which was due to old age.This study has not revealed any connection between previous diseases, the onset of pain, the character and course of the pain, the character of the attack, the localization of pain, precipitating factors, associated symptoms and symptoms of loss on the one hand and the patho-anatomical substratum on the other.The psychological examinations were performed by Mr. Peter Bruun, chief psychologist, for whose cooperation I am grateful.     

Muscle mass effect on arterial desaturation after maximal exercise.

We measured arterial oxygen saturation before and immediately after randomly allocated 6 min of "all-out" maximal arm cranking, treadmill running, and ergometer rowing in 10 men and women with a median maximal oxygen uptake of 4.47 (range 3.22-5.34) 1.min-1. Arterial saturation for oxygen was unaltered after arm cranking, but decreased 1.7 (-2.5-6.0) % (P less than 0.05) after running, and 2.2 (1.0-8.7) % (P less than 0.01) after rowing. Arterial saturation was inversely related to capillary blood lactate, which reached 11.8 (7.4-14.0), 12.6 (8.9-18 2), and 14.3 (12.0-19.3) mmol.l-1 (P less than 0.01), respectively, and arterial bicarbonate fell to 15.0 (13.0-23.6), 12.4 (7.2-20.4), and 10.8 (0.0-12.5) mmol.l-1 (P less than 0.01). Thus, pH decreased to 7.25 (7.22-7.40), 7.17 (6.95-7.35), and 7.09 (6.84-7.19) (P less than 0.01). When measured immediately post-exercise, arterial oxygen tension was unchanged or elevated from rest, eliminating the possibility that the arterial desaturation was caused by a pulmonary diffusion limitation. The results of this investigation show that arterial desaturation associated with maximal exercise takes place in proportion to the involved muscle mass, as do deviations in blood lactate, bicarbonate, and hydrogen concentrations.     

Effect of acetylsalicylic acid on renal function in systemic lupus erythematosus

Summary Glomerular filtration rate (GFR;⁵¹Cr-EDTA clearance), serum creatinine concentration and urinary excretion of prostaglandins were measured in 8 patients with systemic lupus erythematosus (SLE) before and after 2 weeks of treatment with acetylsalicylic acid (ASA). ASA 65 mg/kg or up to 4 g/daily was given as a sustained release preparation. The serum salicylate concentration ranged from 0.3 to 1.6 mmol/l. Serum creatinine after 1 and 2 weeks and GFR after 2 weeks of ASA treatment showed no significant changes. There was a clearcut decrease in urinary excretion of prostaglandins PGE₂ and PGF₂, by 44% and 50%, respectively. It is concluded that therapeutic doses of ASA do not cause deterioration of GFR in patients with SLE and normal or moderately reduced renal function.     

Genetic risk factors in multiple sclerosis and approaches to their identification

Development of multiple sclerosis (MS) is believed to involve genetic as well as environmental factors. A complicating aspect to the study of aetiological factors in MS concerns the possible existence of genetically different subtypes of the disease. In addition, a relatively large number of susceptibility genes could be involved. Most likely, the contribution of the single genes to the susceptibility to MS is modest. However, interactions between different genes could result in a dramatic increase in disease susceptibility (synergistic gene effects). In this short review we focus upon genetic heterogeneity and gene interactions in MS. We also outline approaches to the genetic analysis of complex disease traits such as MS.     

Screening for complement deficiency in bacterial meningitis

Seventy-seven children with bacterial meningitis were screened for complement deficiency. Both the classical and the alternate pathways were normal in 75 patients. Transiently reduced total haemolytic activity of the classical pathway was documented in a boy with meningococcal meningitis. Total haemolytic activity of both the classical and the alternate pathways were reduced in another patient with pneumococcal meningitis: individual complement components determination indicated predominant activation of the alternate pathway.     

No evidence for decreasing semen quality in four birth cohorts of 1,055 Danish men born between 1950 and 1970

Objective: To compare the quality of semen in 1,055 Danish men born between 1950 and 1970 who are assumed to represent a random sample of the Danish male population of fertile age.Design: Retrospective review of data on semen quality at the time of the female partner's first IVF treatment.Setting: The Fertility Clinic, Odense University Hospital, Odense, Denmark.Patient(s): One thousand fifty-five male partners of women with tubal infertility who were referred for IVF treatment consecutively during the period 1990–1996.Intervention(s): Analysis of the semen samples delivered and used in connection with the couples' first IVF treatment.Main Outcome Measure(s): Year of birth, age at time of sample collection, sperm concentration, and semen volume.Result(s): The mean sperm concentration (±SD) was 183.7 x 10⁶ mL and the mean semen volume (±SD) was 3.9 mL. A considerable variation in both parameters was found from year to year, but no significant change occurred in either parameter throughout the entire period. When four birth cohorts were compared, a later year of birth was not associated with any change in sperm concentration or semen volume.Conclusion(s): Sperm concentration and semen volume were not related to year of birth, indicating that sperm quality has not changed in the Danish male population during the last 20–30 years.     

Multivitamin/mineral supplementation improves plasma B-vitamin status and homocysteine concentration in healthy older adults consuming a folate-fortified diet

Elevated homocysteine has been identified as an independent risk factor for cardiovascular and cerebrovascular disease. Although multivitamin use has been associated with low plasma homocysteine concentrations in several observational studies, no clinical trials have been conducted using multivitamin/mineral supplements to lower homocysteine. We determined whether a multivitamin/mineral supplement formulated at about 100% Daily Value will further lower homocysteine concentration and improve B-vitamin status in healthy older adults already consuming a diet fortified with folic acid. In this randomized, double-blind, placebo-controlled trial, 80 free-living men and women aged 50-87 y with total plasma homocysteine concentrations of > or =8 micromol/L received either a multivitamin/mineral supplement or placebo for 56 d while consuming their usual diet. After the 8-wk treatment, subjects taking the supplement had significantly higher B-vitamin status and lower homocysteine concentration than controls (P: < 0.01). Plasma folate, pyridoxal phosphate (PLP) and vitamin B-12 concentrations were increased 41.6, 36.5 and 13.8%, respectively, in the supplemented group, whereas no changes were observed in the placebo group. The mean homocysteine concentration decreased 9.6% in the supplemented group (P: < 0.001) and was unaffected in the placebo group. There were no significant changes in dietary intake during the intervention. Multivitamin/mineral supplementation can improve B-vitamin status and reduce plasma homocysteine concentration in older adults already consuming a folate-fortified diet.     

Paracrine/autocrine regulation of breast cancer by the insulin-like growth factors

Local environmental signals regulate the growth and development of both normal and malignant breast epithelium. Members of the insulin-like growth factor (IGF) family likely influence both of these processes. The localization of IGF2 to stroma specifically surrounding malignant breast epithelium indicates that this growth factor may play a critical role in the genesis or maintenance of this transformed phenotype. Recent studies have sought to understand the mechanism by which IGF2 expressing fibroblasts are localized to the periphery of malignant breast cancer cells. In addition, the consequences of the expression of IGF-signaling components likely expand beyond their direct effects on mitogenesis. Indirect effects predominantly associated with the IGF2 receptor could also influence the invasive potential of breast tumor cells.     

Sonography of tendons

Recent advances in ultrasound technology and the development of high-resolution ultrasound transducers have enabled detailed depiction of superficial musculoskeletal structures. While in the past considered as complementary to magnetic resonance (MR) imaging, modern ultrasound has clearly become competitive. It is now the imaging modality of choice for evaluating tendon pathology. The major advantages of ultrasound include dynamic evaluation of structures, low cost and wide availability. The main disadvantage is a high degree of operator dependency. This article discusses the current ultrasound characteristics of normal tendon, the artefacts that may mimic tendon disease and reviews the applications of ultrasound to the evaluation of tendon disorders, including tendon tears, tendinitis, tenosynovitis, ganglion cysts and bursitis.