Deamidation: a source of microheterogeneity in pharmaceutical proteins

Most protein molecules undergo some degree of spontaneous deamidation in vivo. This process may also occur during the production, isolation, purification, formulation and storage of pharmaceutical proteins. Deamidation is a potential source of microheterogeneity for pharmaceutical proteins, and this is an important issue that needs to be addressed, not only by the manufacturers but also by the national control agencies. This article provides an overview of the scientific and regulatory issues pertinent to deamidation of pharmaceutical proteins.

Real-time VanderLugt optical correlator that uses photorefractive GaAs

A real-time GaAs and liquid-crystal television- (LCTV-) based optical correlator is demonstrated. The speed of this correlator (video rate) is limited by the LCTV's; with faster spatial light modulators, the potential speed of a GaAs-based correlator may be 1000 frames/s or higher. Comparisons are made between VanderLugt and joint transform configurations and between degenerate and nondegenerate four-wave mixings. The edge-enhancement effect and the Bragg diffraction effect are also discussed.

Chorionic villus sampling: evaluation of obstetric performance

Chorionic villus sampling is frequently utilised in the Nottingham region as a means of early prenatal diagnosis of genetic problems. Its relative safety in the early antenatal period is well established but there has been some concern that perinatal mortality may be greater in the chorionic villus sampling group as compared to amniocentesis. We have in response studied our own data and report the obstetric outcome in 144 cases where the pregnancy has progressed beyond 28 weeks gestation. We have selected a procedure free control group matched for parity. We have found no significant difference in the perinatal outcome and obstetric performance and conclude that at this juncture we should continue to offer our services as chorionic villus sampling offers significant advantages in the first trimester over amniocentesis.

Primary structure of thymosin beta 12, a new member of the beta-thymosin family isolated from perch liver

A new polypeptide termed thymosin beta 12 has been isolated from perch liver and its primary structure elucidated. This polypeptide contains 43 amino acid residues with a molecular weight of 4822 Da. The content of thymosin beta 12 from perch liver has been determined as 43 micrograms/g of tissue. The amino-terminal end of this polypeptide is blocked by an acetyl group as deciphered by fast-atom bombardment mass spectrometric analysis. Sequence analysis reveals that thymosin beta 12 is 79% homologous to thymosin beta 4, an immunomodulator which was originally isolated from calf thymus. Thymosin beta 12 also shows 84% sequence homology to thymosin beta 11, a beta 4 analog which replaces beta 4 in two species of bony fish, oscar and rainbow trout. The evolutionary implication of such results will be discussed. The isolation of a new beta 4-related peptide from perch liver which differs from beta 11 indicates that beta-thymosin peptides are widely distributed in lower vertebrate classes.

Inhibitory effect of circulating insulin on glucagon secretion during hypoglycemia in type I diabetic patients

OBJECTIVE

To clarify whether the circulating insulin level influences hormonal responses, glucagon secretion in particular, during hypoglycemia in patients with insulin-dependent (type I) diabetes.

RESEARCH DESIGN AND METHODS

Nine type I diabetic patients were studied. During two separate experiments, hypoglycemia was induced by low-dose (244 pmol.kg-1.h-1) and high-dose (1034 pmol.kg-1.h-1) intravenous insulin infusions for 180 min in each case. The arterial blood glucose level was directly monitored every 1.5 min, and glucose was infused in the high-dose test to clamp the arterial blood glucose level to be identical as in the low-dose test.

RESULTS

Despite the fact that the plasma insulin level was four times higher in the high-dose than in the low-dose test (740 +/- 50 vs. 180 +/- 14 pM), a close to identical arterial hypoglycemia of approximately 3.3 mM was obtained in the two experiments. During hypoglycemia, a significant rise of the plasma glucagon level was found only in the low-dose test (188 +/- 29 vs. 237 +/- 37 ng/L, P less than 0.05), and the incremental area under the glucagon curve was significantly greater in the low-dose than in the high-dose test (140 +/- 19 vs. -22.7 +/- 34 ng/L.h-1, P less than 0.005). The responses of plasma epinephrine, norepinephrine, growth hormone, pancreatic polypeptide, and somatostatin were similar in both tests and, consequently, were not significantly modified by the circulating insulin level.

CONCLUSIONS

This study demonstrates that, in type I diabetic patients, the glucagon response to hypoglycemia is suppressed by a high level of circulating insulin within the physiological range. Our findings may help to explain the impairment of glucagon secretion during hypoglycemia frequently seen in these patients.

Intraplacental sonolucent spaces: incidences and relevance to chorionic villus sampling

Detailed ultrasound examination of the placentae from 293 consecutive women requesting first-trimester chorionic villus sampling (CVS) showed evidence of intraplacental sonolucent spaces with varying density in 42.3 per cent of these placentae. Their presence, however, did not complicate the subsequent course of these women's pregnancies. Their prime significance relates to CVS, where inadvertent entry into these areas can lead to bleeding and contamination of the villus specimens with blood. A search for these spaces should be made before sampling, and when present, they should be avoided wherever possible.

Bleeding as a consequence of chorion villus sampling

A series of 4 separate studies were conducted to assess the incidence and short term consequence of bleeding associated with chorion villus sampling. Results support previous reports that risk of foetal-maternal transfusion as suggested by a rise in maternal serum alpha-fetoprotein (MSAFP) can occur. This occurrence is not consistent and need not be obvious even after therapeutic abortion. It is also transient and did not complicate mid-trimester neural tube screening or subsequent course of pregnancy. Eighty-seven percent of blood contaminating villus samples are of maternal origin. Following diagnosis 37% of patients reported some vaginal bleeding. This is mainly in the form of spotting which did not preclude normal pregnancy. Foetal loss occurred in 4 of the patients when bleeding considered heavier than spotting continued. In rhesus negative patients prophylactic anti-D gamma-globulin is advised, since neither Kleihauer counts nor MSAFP estimation reliably detect all foetal-maternal transfusions.

A prospective study of spontaneous miscarriage in ultrasonically normal pregnancies and relevance to chorion villus sampling

A total of 1,068 patients were examined by ultrasound to ensure normality of pregnancy and followed prospectively from booking until 28 weeks. The spontaneous miscarriage rate was 2.7 per cent occurring within the first 16 weeks. Threatened miscarriage was associated with a 38 per cent fetal loss. Miscarriage was less likely as pregnancy advanced. The reduction in subsequent miscarriage rate before 11 weeks and from 11 weeks onwards is statistically significant (p less than 0.001). Gravidity, maternal age and a history of previous fetal loss did not contribute significantly to the miscarriage rate. Patients with a history of fetal loss were more likely to experience a threatened miscarriage. The relevance of these findings to chorion villus sampling is discussed.

Nefopam excretion in human milk

Human milk and plasma samples were obtained from five healthy nursing mothers who were taking nefopam hydrochloride (60 mg four-hourly) for post-episiotomy pain. Concentrations of nefopam were quantified in milk and plasma paired samples, taken daily from birth for 5 days, by a specific paired-ion reverse phase h.p.l.c. method. Although nefopam was present in human milk in an equivalent concentration to plasma (milk: plasma ratio 1.2 +/- 0.7, mean +/- s.d.), the likely infant exposure was less than 0.05 mg kg-1 day-1 which, on a body weight basis, would be less than 3% of the maternal dose.

Endometriosis: its association with retrograde menstruation, dysmenorrhoea and tubal pathology

Seventy-five women admitted for sterilization were laparoscoped during menstruation. Retrograde spillage of menstrual blood was observed in 76%. The occurrence of dysmenorrhoea was not associated with spillage of menstrual blood, observed endometriosis or tubal pathology. Mild or stage I endometriosis was detected in 43% of all the women but in only 54% of those who had retrograde spill. Retrograde spill was seen in 97% of those with endometriosis. A significant association (P less than 0.001) was found between endometriosis and tubal damage not due to endometriosis. The implication of these findings are discussed.

Transcervical chorionic villus biopsy with a brush

A brush delivered to the biopsy site by a metal introducer and cannula set was tested as an alternative implement for transcervical collection of chorionic villi. This implement was easy to use and readily identified by ultrasound. With only one attempt at sampling, the overall collection rate for 83 patients was 65 per cent. With practice 84 per cent successful collection was achieved. Gestations between 8 and 11 weeks was the best time for collection of chorionic villi. A single sampling can produce adequate material (15 mg wet weight) suitable for diagnostic purposes. No gestation sac was perforated but some slight bleeding followed the procedure. Appreciable success following a single sampling attempt coupled with the low complication rate suggests that this technique may have clinical application and deserves further investigation.

Nephrotoxic serum nephritis with hypertension: amelioration by antihypertensive therapy

We have examined the effects of antihypertensive therapy on glomerular dynamics and on the clinical and morphologic features of a model of nephrotoxic serum nephritis (NSN) in which hypertension occurs. NSN was induced in uninephrectomized male Sprague Dawley rats, which drank 0.9% sodium chloride ad libitum. One-half were assigned randomly to a treated group whose blood pressure was normalized on a regimen of reserpine, hydralazine, and hydrochlorothiazide. Hypertension continued throughout the 6 weeks of study in untreated rats (blood pressure 148 +/- 5 vs. 103 +/- 3 mm Hg in treated rats, P less than 0.01). Urinary protein excretion was greater (437 +/- 110 vs. 254 +/- 81 mg/24 hr, P less than 0.005), and serum albumin lower (1.6 +/- 0.4 vs. 2.9 +/- 0.3 g/dl, P less than 0.01) in hypertensive animals. Diffuse glomerular endo- and extracapillary proliferation and arteriolar medial hypertrophy were observed frequently in nephritic rats with untreated hypertension. By contrast, structural abnormalities were limited primarily to focal segmental proliferation involving fewer than one-third of glomeruli in the absence of vascular changes in treated normotensive rats. Micropuncture studies performed 8 to 16 days after induction of nephritis showed a reduction in glomerular capillary pressure (46 +/- 1 vs. 55 +/- 1 mm Hg, P less than 0.001), glomerular plasma flow rate (115 +/- 20 vs. 160 +/- 20 nl/min, P less than 0.01), and single nephron filtration rate (42 +/- 4 vs. 56 +/- 5 nl/min, P less than 0.001) with antihypertensive treatment, suggesting that a hemodynamic mechanism may have been responsible for enhanced glomerular injury in the hypertensive nephritic animals.

Severe heparin osteoporosis in pregnancy

A case of severe osteoporosis following administration of low dose subcutaneous heparin in pregnancy is reported. Possible reasons for the condition are suggested which caution against the indiscriminate use of subcutaneous heparin in pregnancy.

Trophoblast sampling by blind transcervical aspiration

Blind transcervical aspiration for trophoblast was carried out on 137 patients undergoing elective termination of early pregnancies. Trophoblast was obtained from 45 patients (33%) usually at the first attempt. Collection was not necessarily more successful between 8 and 11 weeks of gestation. In only 13 patients (9%) was trophoblast collected without contamination by maternal tissue, or blood. Perforation of the amniotic sac in one patient (1%), bleeding either observed, or detected histologically (34%) and introduction of infection (4%) constitutes a real threat to fetal survival. Maternal serum alpha-fetoprotein estimation appears useful and may forewarn likelihood of fetal damage. Although transcervical aspiration should encounter ready acceptability as an out-patient procedure, modifications in the technique are essential before clinical application for detection of gene, or chromosome anomalies can be considered.

Endometriosis: associations with menorrhagia, infertility and oral contraceptives

In a retrospective study of 163 women with endometriosis, 76% had a history of menorrhagia, a larger percentage than that which might be normally expected. Only 10% of the women complained of infertility, while 13% had used oral contraceptives regularly, a much smaller proportion than expected. These findings are discussed in terms of the pathogenesis of endometriosis and the possible prophylactic role of oral contraceptives. The authors suggest the possibility that increased sensitivity to estrogens may lead to the development of endometriosis in some women.

Placental localization by liquid crystal thermography

The accuracy of determining placentation by using plates of cholesteric thermocrystals has been studied, with the actual placental site being defined as that shown by ultrasound B scanning. In our study, 43 patients were examined, including eight with placenta previa. Although all eight cases of placenta previa were identified, there were three false-positive test results. It is believed that suitable modification of the composition of the liquid crystal mixture will improve the accuracy of this simple technique, which would be valuable in areas where sophisticated equipment is not yet available.

An improved method for the preparation of intermediate-purity antihemophilic factor concentrate for therapeutic usage

An improved method involving pH changes in the process for the preparation of intermediate-purity antihemophilic concentrate offers several advantages over the standard method. Antihemophilic concentrates thus prepared are more soluble, more purified and more stable than the standard antihemophilic concentrates. High-potency antihemophilic concentrates with good solubility may be obtained by concentrating the [in-process] solution before lyophilization.

Case report--pregnancy and intestinal lymphangiectasis (familial neonatal hypoproteinaemia)

A patient with a history of familial intestinal lymphangiectasis and exudative enteropathy was observed during 2 consecutive pregnancies. Normal pregnancy is compatible with the condition and pregnancy need not aggravate the disease.

Removal of anticomplementary activity from human immune serum globulins by treatment with purified human plasmin

Human immune serum globulin preparations were treated with highly purified human plasmin to remove their anticomplementary activity. The extent of anticomplementary activity removed and the amount of fragmentation obtained from immune serum globulin preparation depended upon the amount of plasmin added and the length of incubation time. The enzymatic reaction was stopped by removing plasmin with bentonite adsorption. Two types of plasmin-treated immune serum globulin that may be used for intravenous injection were obtained. One was a more fragmented product (35 to 45%) with lower anticomplementary activity, the other was a less degraded product (15 to 20%) with slightly higher anticomplementary activity. Antibody content of the former preparation was somewhat reduced while that of the latter preparation was virtually unchanged from the untreated immune serum globulin.

The value of a scoring system in predicting outcome of pre-term labour and comparing the efficacy of treatment with aminophylline and salbutamol

A simple score, derived by allocating points to a selection of factors which influence the outcome of pre-term labour, was found to relate to the success of treatment. Used as a measure of the situation before therapy, this score can define a baseline allowing a realistic comparison of therapeutic methods. In this series, despite treatment, a large number of patients still were delivered before term and within a few days of admission to hospital. Thus it would seem that although drugs suppress uterine activity, they cannot neutralize the adverse effects of other factors associated with pre-term labour.

The relevance of antenatal and intrapartum fetal heart rate patterns to fetal outcome

Antenatal fetal heart rate (FHR) as an indicator of fetal status was evaluated in two separate studies. The first attempted to determine, in 30 minutes of continuous recording from each of 50 antenatal patients, relationships between spontaneous FHR changes and fetal condition before and after birth. No significant association was found between observed FHR patterns and antenatal or neonatal fetal status. The second study used induction of labour as a stress test, because similar conditions to that required for oxytocin stress testing were present and there was the advantage of direct FHR recording. In 150 induced and monitored labours, FHR changes associated with the first six suitable contractions seldom related to Apgar scores at birth or development of fetal distress in active labour. Fetuses showing no response to contractions tended to have better Apgar scores than those which showed FHR decelerations. Results from these studies do not substantiate reports that FHR changes arising spontaneously, or in response to induced contractions, reflect satisfactorily the existing or subsequent fetal status.

Progression in response patterns of fetal heart rate throughout labour

A study of 70 fetal heart rate (FHR) traces throughout labour has allowed analysis of FHR responses associated with approximately 7000 individual uterine contractions. The significance of the less emphasized FHR patterns has been assessed and an attempt has been made to identify any trend or progression in the occurrence of these patterns. Transient acceleration was the most frequently occurring response in early labour and was the first observed response in the majority of cases. Decelerations became prevalent as labour progressed. A hypothesis is proposed to explain the observed overall progression in FHR responses and the possible physiological mechanisms underlying the cyclic changes in response patterns which occur throughout the course of labour.

Assessment of diagnostic aspiration curettage as an outpatient procedure

Aspiration curettage proved acceptable to patients and medical staff when incorporated into a busy outpatient practice. The diagnostic reliability of curettings obtained was shown to be 93.5 per cent accurate. In all patients where mucus only is obtained, where symptoms persist or recur, or when aspiration curettage is too distressing, conventional curettage is mandatory.

Dilatation of the parous non-pregnant cervix

In vitro cervical dilatations were carried out on 33 uteri removed by hysterectomy for conditions not involving the cervix from parous women in their reproductive span of life. A specially designed force measuring dilator was used for all the tests. The analysis of the results involved the application of a thick-walled cylindrical stress determination technique. Using this approach it was possible to calculate quasi-elastic moduli for different degrees of dilatation and obtain theoretical distributions of radial and circumferential stress across the cervical wall. These results indicated a yielding of the cervical tissue at about 9 to 11 mm. dilatation in a significant number of cases.