Albertus Timmer

The Tulip classification of perinatal mortality: introduction and multidisciplinary inter-rater agreement

Objective  To introduce the pathophysiological Tulip classification system for underlying cause and mechanism of perinatal mortality based on clinical and pathological findings for the purpose of counselling and prevention.

Diverse placental pathologies as the main causes of fetal death.

OBJECTIVE: To estimate the occurrence of placental causes of fetal death in relation to different gestational ages and their clinical manifestations during pregnancy. METHODS: In a prospective cohort study conducted from 2002 to 2006, we studied 750 couples with singleton intrauterine fetal death after 20 weeks of gestation. Cause of death was classified according to the Dutch Tulip cause of death classification for perinatal mortality. Differences between groups for categorical data were evaluated by the Fisher exact test or &khgr;2 test. RESULTS: The main causes were placental pathology (64.9%), congenital anomaly (5.3%), infection (1.9%), other (4.8%), and unknown (23.1%). The contribution of causes differed over gestational age periods. At lower gestational age, placental and unknown were the most dominant causes of death (34.8% and 41.7%, respectively); at higher gestational age, the relative importance of an unknown cause decreased and a placental cause increased (16.5% and 77.6%) (P<.001). Placental bed pathology was observed in 33.6% of all fetal deaths, with the highest occurrence between 24 0/7 and 31 6/7 weeks and a strong decline after 32 weeks. In contrast, contribution of developmental placental pathology (17.6%) increased after 32 weeks of gestation (P<.001), as did umbilical cord complications (5.2%) and combined placental pathology (5.4%). Solitary placental parenchyma pathology was less frequent (3.1%). Hypertension-related disease was observed in 16.1% (95% confidence interval [CI] 13.6–19.0) of the cohort, small for gestational age fetuses in 37.9% (95% CI 34.1–41.7), and diabetes-related disease in 4.1% (95% CI 2.8–5.8). CONCLUSION: Most fetal deaths were caused by a variety of placental pathologies. These were related to gestational age, and their clinical manifestations varied during pregnancy. LEVEL OF EVIDENCE: II

Cytogenetic analysis after evaluation of 750 fetal deaths: proposal for diagnostic workup

OBJECTIVE: To estimate success rates for cytogenetic analysis in different tissues after intrauterine fetal death, and study selection criteria and value of cytogenetic testing in determining cause of death. METHODS: Cytogenetic analyses and the value of this test in determining cause by a multidisciplinary panel were studied in 750 fetal deaths. Morphologic abnormalities, small for gestational age (SGA), advanced maternal age (older than 35 years) and maceration were studied as selection criteria. RESULTS: Chromosomal abnormalities were observed in 13% of fetal deaths. Cytogenetic success rates were significantly higher for invasive testing (85%) than for postpartum tissue analysis (28%, P<.001). There were more abnormal chromosomes (38%) in fetal deaths with morphologic abnormalities than in those without (5%, P<.001). This was not observed for SGA (16% compared with 9.2%, P=.22) or for advanced maternal age (16.7% compared with 12.0%, P=.37). The posterior probability of a chromosomal abnormality in the absence of morphologic abnormalities was still 4.6%. Cytogenetic analysis was successful in 35% of severely macerated fetuses. We do not advise using these selection criteria, because the failure rate was high on postpartum tissues. Cytogenetic analysis was valuable in determining the cause in 19% of the fetal deaths. CONCLUSION: Parents should be counseled on aspects of cytogenetic analysis after fetal death. We advise performing nonselective invasive testing after fetal death and before labor for all fetal deaths. LEVEL OF EVIDENCE: II

ADAM17 upregulation in human renal disease: a role in modulating TGF-alpha availability?

A disintegrin and metalloproteinase (ADAM)17 sheds growth factors from the cell membrane, including epidermal growth factor receptor (EGFR) ligand transforming growth factor (TGF)-alpha. In mice, angiotensin II infusion induces renal fibrosis via ADAM17-mediated TGF-alpha shedding and subsequent EGFR activation. Pharmacological ADAM17 inhibition reduced renal fibrotic lesions and improved renal function, positioning ADAM17 as a promising target of intervention in renal disease. We studied ADAM17 expression in the human kidney. ADAM17 mRNA was constitutively expressed in normal adult kidneys, with highest expression in distal tubules. In human renal disease, ADAM17 was de novo expressed in proximal tubules, peritubular capillaries, and glomerular mesangium and upregulated in podocytes. Glomerular mesangial and endothelial ADAM17 were associated with mesangial matrix expansion, focal glomerulosclerosis, and glomerular macrophage infiltration (P < 0.01). Peritubular capillary and proximal tubular ADAM17 were associated with interstitial fibrosis and interstitial macrophage infiltration (P < 0.05). Both glomerular and interstitial ADAM17 were associated with decreased renal function (P < 0.05). In renal fibrosis, ADAM17 colocalized with TGF-alpha. Moreover, in cultured human podocytes and proximal tubular cells, pharmacological ADAM17 inhibition reduced constitutive TGF-alpha shedding by 78% (P < 0.005) and 100% (P < 0.05), respectively, and phorbol ester-induced TGF-alpha shedding by 84% (P < 0.005) and 92% (P = 0.005), respectively. Finally, ADAM17 inhibition reduced cellular proliferation. In conclusion, the ADAM17 expression pattern and its role in shedding TGF-alpha from cultured human kidney cells suggest a role in the development of fibrosis. Since EGFR signaling is implicated in renal fibrosis, targeting ADAM17 to reduce availability of EGFR ligand TGF-alpha may represent a promising way of intervention in human renal disease.

Morphology of testicular parenchyma adjacent to germ cell tumours. An interim report

A comparative morphological analysis of parenchyma adjacent to testicular germ cell tumours (TGCT) was performed in a series of 181 orchidectomy specimens: 86 with seminomas (Se), 72 with nonseminomatous germ cell tumours (NS) and 23 with combined tumours (CT, which have a Se and a NS component). The following morphological features were semiquantitatively scored: spermatogenesis (modified Johnsen score); amount of tubular atrophy; amount of carcinoma in situ (CIS); amount of intertubular tissue. Absence and presence was scored for the following features: lymphocytic infiltrate surrounding and invading CIS; intratubular seminoma (ISe); intratubular nonseminoma (INS); microlithiasis; diffuse and nodular hyperplasia of Leydig cells; angioinvasiveness; testicular angiopathy. Using non‐parametric statistics these features were correlated with each other and with tumour type, tumour size and age of the patient. Se‐patients presented at significantly higher age than NS‐patients (36 vs 29 years, p=0.001). The age of patients with CT (32 years) was in between that of Se‐ and NS‐patients. No correlation was found between patient age and tumour size. Parenchyma adjacent to Se, compared to parenchyma adjacent to NS had the following significant differences: a lower Johnsen score (5.6 vs 7.2, p=0.005); less frequent (85% vs 97% of specimens, p=0.016) and a lesser amount of CIS (26% vs 32% of tubules, p=0.015); more frequent peri‐ (80% vs 60% of specimens, p=0.001) and intratubular (68% vs 30% of specimens, p=0.001) lymphocytic infiltrates; more extensive tubular atrophy (36% vs 15% of tubules, p=0.001); and a larger area of intertubular tissue (42% vs 34% of parenchyma area, p=0.016). The pooled Se and CT had a significantly higher frequency of ISe than the NS (31% vs 17% of specimens, p=0.036). With one exception INS was only found adjacent to NS or CT, with a frequency of 16%, and 20% of the specimens, respectively. It was significantly associated with angio‐invasiveness. In specimens lacking angio‐invasion the frequency of INS was 6%. The correlation of INS with tumour size and patient age was studied in a series of 145 NS and CT (95 from the original series supplemented by 50 newer cases). In this series INS was significantly associated with smaller tumours and younger patients. Extensive tubular atrophy was significantly correlated with higher age, the diagnosis of Se, a low Johnsen score, and the presence of angiopathy. The more tubular atrophy, the less CIS (both in incidence and amount). Inversely, a higher Johnsen score is associated with smaller tumours, the diagnosis of NS or CT, a higher incidence and a larger amount of CIS, and little tubular atrophy. Tubules with mature spermatogenesis were found in 42% of the specimens regardless of tumour type. We conclude that ISe and INS are probably frequent intermediate stages between CIS and Se and NS, respectively. The features of parenchyma adjacent to Se are probably due to the host response elicited by the invasive Se, which secondarily also affects CIS. The long time to clinical presentation allows the host to eradicate most of the CIS by the time the tumour is surgically removed. The much less extensive morphological features of a host response in parenchyma adjacent to NS support the contention that NS originates as INS, behind the blood/testis barrier, without exposure of the host to tumour cells with a seminomatous phenotype (CIS‐ or Se cells). Microlithiasis and testicular angiopathy are frequent, but not specific findings in parenchyma next to TGCT. Their relationship with the development with TGCT is unexplained.

Hydrogen sulfide producing enzymes in pregnancy and preeclampsia

Preeclampsia, a human pregnancy specific disorder is characterized by an anti-angiogenic state. As hydrogen sulfide (H(2)S) has pro-angiogenic and anti-oxidative characteristics, we hypothesized that H(2)S levels could play a role in the pathogenesis of preeclampsia and studied the placental expression of the H(2)S-producing enzymes cystathionine-γ-lyase (CSE) and cystathionine-β-synthase (CBS). CBS and CSE protein are expressed in the fetal-placental endothelium and CBS only in Hofbauer cells. CBS mRNA expression is decreased (p = 0.002) in early-onset preeclampsia, while CSE mRNA is unchanged. Thus, down regulation of CBS during early-onset preeclampsia may result in less H(2)S-production and may aid in the anti-angiogenic state.

Infantile and adult testicular germ cell tumors: a different pathogenesis?

Most adult testicular germ cell tumors have a characteristic chromosomal abnormality that is an isochromosome 12p [i(12p)]. Furthermore, these tumors are characterized by a chromosome number in the triploid range and gains and losses of (parts of) specific chromosomes. Cytogenetic investigation of three cases of infantile testicular germ cell tumors, all diagnosed as yolk sac tumors, revealed highly abnormal karyotypes. We found one case to be diploid; the other two cases were in the hypertriploid/hypotetraploid range. Structural abnormalities of chromosomes 1, 3, and 6 were recurrent and no i(12p) was found. Our results, together with data from the literature, suggest that infantile and adult testicular germ cell tumors have a different origin and pathogenetic pathway. Aberrations of chromosomes 1, 3, and 6 may play an important role in the pathogenesis of infantile testicular yolk sac tumors.

Plasma hemopexin activity in pregnancy and preeclampsia.

Objective: Plasma hemopexin activity, associated with increased vascular permeability, was evaluated in healthy pregnant and non-pregnant women and in pre-eclamptic women. Methods: Hemopexin activity and the hemopexin inhibitor, extracellular ATP, were assayed in plasma from pregnant (n = 10), preeclamptic (n = 9), and non-pregnant women (n = 10) using standard methods. Abdominal fascia tissue fragments from preeclamptic and pregnant women were immunohistochemically stained for vascular ecto-apyrase or ecto-5′nucleotidase. Results: The data show significantly enhanced Hx activity exclusively in plasma from pregnant women and significantly enhanced plasma ATP in pre-eclamptic women compared with the other groups. Dephosphorylation of preeclamptic plasma resulted in reactivation of Hx activity. Fascia tissue-samples from preeclamptic women showed reduced ecto-apyrase activity and enhanced ecto-5′nucleotidase activity compared to pregnant women. Conclusion: Enhanced hemopexin activity may be associated with normal pregnancy, but not with preeclampsia. Decreased hemopexin in pre-eclamptic patients may be due to enhanced plasma ATP, which is possibly promoted by diminished activity of vascular ecto-apyrase.

Role of metallothionein in cisplatin sensitivity of germ-cell tumours

Cisplatin (CDDP) is an extremely active drug in the treatment of germ‐cell tumours. Earlier, we found an unexpected inverse correlation between the total amount of sulfhydryl groups and CDDP sensitivity in a panel of 3 human germ‐cell‐tumour and 3 colon‐carcinoma cell lines. Major components of the sulfhydryl groups are glutathione and metallothionein (MT). We further investigated a possible role of MT in the CDDP sensitivity of germ‐cell tumours. MT levels and functionality of the germ‐cell‐tumour and colon‐carcinoma cell lines were found to be inversely correlated with CDDP sensitivity. No difference in sub‐cellular localization of MT could be observed among the types of cell lines. In agreement with the in vitro data, immunohistochemical detection of MT was high in 11/14 primary human germ‐cell tumours and low in 7/7 human colon carcinomas. MT‐protein expression in primary germ‐cell tumours did not discriminate between responding and non‐responding patients. As compared with the primary tumours, MT‐protein expression decreased in 5/7 post‐chemotherapy residual vital tumours or remained undetectable (2/7). MT‐protein expression in the germ‐cell tumours was not related to total p53‐protein expression. In summary, over‐expression of MT was found in germ‐cell tumours, both in cell lines and in human tumours. Although MT‐protein over‐expression seems to be associated with the CDDP sensitivity of germ‐cell tumours, MT‐protein expression in primary germ‐cell tumours did not differ between responding and non‐responding patients and therefore cannot be used to predict response to chemotherapy. Int. J. Cancer 85:777–781, 2000.

Altered expression of immune-associated genes in first-trimester human decidua of pregnancies later complicated with hypertension or foetal growth restriction

During pregnancy the maternal immune system has to coordinate uterine spiral-artery remodelling, trophoblast invasion, and acceptance of the semi-allogenic fetus simultaneously. As dysregulation of the immune system is associated with adverse pregnancy outcomes, we analysed first-trimester deciduas of pregnancies for immune parameters in later complicated pregnancies. Higher IL6 and macrophage mRNA expression, and lower ratios of regulatory macrophages were found in first-trimester deciduas of pregnancies later complicated with pregnancy-induced hypertension. Lower Gata3 (Th2) mRNA expression was found in deciduas of pregnancies with later foetal growth restriction. Our results suggest that adverse pregnancy outcomes are associated with immunological disturbances in first-trimester deciduas.