ABE8e Corrects Pax6-Aniridic Variant in Humanized Mouse ESCs and via LNPs in Ex Vivo Cortical Neurons

INTRODUCTION

Aniridia is a rare congenital vision-loss disease caused by heterozygous variants in the PAX6 gene. There is no vision-saving therapy, but one exciting approach is to use CRISPR/Cas9 to permanently correct the causal genomic variants. Preclinical studies to develop such a therapy in animal models face the challenge of showing efficacy when binding human DNA. Thus, we hypothesized that a CRISPR gene therapy can be developed and optimized in humanized mouse embryonic stem cells (ESCs) that will be able to distinguish between an aniridia patient variant and nonvariant chromosome and lay the foundation for human therapy.

METHODS

To answer the challenge of binding human DNA, we proposed the "CRISPR Humanized Minimally Mouse Models" (CHuMMMs) strategy. Thus, we minimally humanized Pax6 exon 9, the location of the most common aniridia variant c.718C > T. We generated and characterized a nonvariant CHuMMMs mouse, and a CHuMMMs cell-based disease model, in which we tested five CRISPR enzymes for therapeutic efficacy. We then delivered the therapy via lipid nanoparticles (LNPs) to alter a second variant in ex vivo cortical primary neurons.

RESULTS

We successfully established a nonvariant CHuMMMs mouse and three novel CHuMMMs aniridia cell lines. We showed that humanization did not disrupt Pax6 function in vivo, as the mouse showed no ocular phenotype. We developed and optimized a CRISPR therapeutic strategy for aniridia in the in vitro system, and found that the base editor, ABE8e, had the highest correction of the patient variant at 76.8%. In the ex vivo system, the LNP-encapsulated ABE8e ribonucleoprotein (RNP) complex altered the second patient variant and rescued 24.8% Pax6 protein expression.

CONCLUSION

We demonstrated the usefulness of the CHuMMMs approach, and showed the first genomic editing by ABE8e encapsulated as an LNP-RNP. Furthermore, we laid the foundation for translation of the proposed CRISPR therapy to preclinical mouse studies and eventually patients with aniridia.

LNP-mediated delivery of CRISPR RNP for wide-spread in vivo genome editing in mouse cornea

CRISPR/Cas9-based genome-editing therapies are poised to change the clinical outcome for many diseases with validated therapeutic targets awaiting an appropriate delivery system. Recent advances in lipid nanoparticle (LNP) technology make them an attractive platform for the delivery of various forms of CRISPR/Cas9, including the efficient and transient Cas9/gRNA ribonucleoprotein (RNP) complexes. In this study, we initially tested our novel LNP platform by delivering pre-complexed RNPs and template DNA to cultured mouse cortical neurons, and obtained successful ex vivo genome editing. We then directly injected LNP-packaged RNPs and DNA template into the mouse cornea to evaluate in vivo delivery. For the first time, we demonstrated wide-spread genome editing in the cornea using our LNP-RNPs. The ability of our LNPs to transfect the cornea highlights the potential of our novel delivery platform to be used in CRISPR/Cas9-based genome editing therapies of corneal diseases.

Spontaneous, solvent-free entrapment of siRNA within lipid nanoparticles

Lipid nanoparticle (LNP) formulations of nucleic acid are leading vaccine candidates for COVID-19, and enabled the first approved RNAi therapeutic, Onpattro. LNPs are composed of ionizable cationic lipids, phosphatidylcholine, cholesterol, and polyethylene glycol (PEG)-lipids, and are produced using rapid-mixing techniques. These procedures involve dissolution of the lipid components in an organic phase and the nucleic acid in an acidic aqueous buffer (pH 4). These solutions are then combined using a continuous mixing device such as a T-mixer or microfluidic device. In this mixing step, particle formation and nucleic acid entrapment occur. Previous work from our group has shown that, in the absence of nucleic acid, the particles formed at pH 4 are vesicular in structure, a portion of these particles are converted to electron-dense structures in the presence of nucleic acid, and the proportion of electron-dense structures increases with nucleic acid content. What remained unclear from previous work was the mechanism by which vesicles form electron-dense structures. In this study, we use cryogenic transmission electron microscopy and dynamic light scattering to show that efficient siRNA entrapment occurs in the absence of ethanol (contrary to the established paradigm), and suggest that nucleic acid entrapment occurs through inversion of preformed vesicles. We also leverage this phenomenon to show that specialized mixers are not required for siRNA entrapment, and that preformed particles at pH 4 can be used for in vitro transfection.

Enhanced immune response to MMP3 stimulation in microglia expressing mutant huntingtin

Huntington's Disease (HD) is an inherited neurodegenerative disease caused by a polyglutamine expansion in the huntingtin protein. The YAC128 mouse model of HD expresses the full-length human huntingtin protein with 128 CAG repeats and replicates the phenotype and neurodegeneration that occur in HD. Several studies have implicated a role for neuroinflammation in HD pathogenesis. Studies on presymptomatic HD patients have illustrated microgliosis (activated microglia) in brain regions affected in HD. Mutant huntingtin expressing isolated primary monocytes (human HD patients) and primary macrophages (YAC128) are overactive in response to lipopolysaccharide (LPS) stimulation. In this study we demonstrate that cultured primary microglia (the resident immune cells of the brain cells) from YAC128 mice differentially express a wide number of cytokines compared to wildtype microglia cultures in response to LPS. Furthermore, this study outlines a direct interaction between mutant huntingtin and cytokine secretion in HD microglia. Increased cytokine release in YAC128 microglia can be blocked by cannabinoid activation or by mutant huntingtin knockdown with anti-sense oligonucleotide treatment. Matrix metalloprotease 3 (MMP3), an endogenous neuronal activator of microglia, also induces increased cytokine release from YAC128 microglia compared to wildtype microglia. We found elevated MMP levels in HD CSF, and MMP levels correlate with disease severity in HD. These data support a novel role for MMPs and microglial activation in HD pathogenesis. With an improved understanding of the specific cellular processes involved in HD neuroinflammation, novel therapeutic agents targeting these processes can be developed and hold great promise in the treatment of HD.

[Diffuse pulmonary meningotheliomatosis]

In two patients with bilateral micronodular pulmonary changes a diffuse pulmonary meningotheliomatosis was found. A 73-year-old woman presented with bilateral disseminated miliary pulmonary nodules as a radiological incidental finding. The surgical lung biopsy showed multiple tiny nodular proliferations meningothelial-like cells, corresponding "minute pulmonary meningothelial-like nodules", MPMN. A 60-year-old lady with similar radiological findings showed also proliferations of meningothelial-like cells in a transbronchial cryo-biopsy. These lesions are well known to pathologists as curious isolated incidental findings on histological examination of lung specimens. The here described diffuse form of these changes is very rare; its knowledge is important for the differential diagnosis with neoplastic proliferations and other diffuse parenchymal diseases of the lung. This rare diagnosis is made on histological grounds and is also possible in transbronchial biopsies when careful correlation with clinical and radiological data, knowledge of the entity and adequate specimens are provided.

Regulation of pregnancy-associated plasma protein A2 (PAPPA2) in a human placental trophoblast cell line (BeWo)

BACKGROUND

Pregnancy-associated plasma protein A2 (PAPPA2) is an insulin-like growth factor-binding protein (IGFBP) protease expressed at high levels in the placenta and upregulated in pregnancies complicated by preeclampsia and HELLP (Hemolytic anemia, Elevated Liver enzymes, and Low Platelet count) syndrome. However, it is unclear whether elevated PAPPA2 expression causes abnormal placental development, or whether upregulation compensates for placental pathology. In the present study, we investigate whether PAPPA2 expression is affected by hypoxia, oxidative stress, syncytialization factors or substances known to affect the expression of PAPPA2's paralogue, PAPPA.

METHODS

BeWo cells, a model of placental trophoblasts, were treated with one of the following: hypoxia (2% O2), oxidative stress (20 microM hydrogen peroxide), forskolin (10 microM and 100 microM), TGF-beta (10 and 50 ng/mL), TNF-alpha (100 ng/mL), IL-1beta (100 ng/mL) or PGE2 (1 microM). We used quantitative RT-PCR (qRT-PCR) to quantify the mRNA levels of PAPPA2, as well as those of PAPPA and ADAM12 since these proteases have similar substrates and are also highly expressed in the placenta. Where we observed significant effects on PAPPA2 mRNA levels, we tested for effects at the protein level using an in-cell Western assay.

RESULTS

Hypoxia, but not oxidative stress, caused a 47-fold increase in PAPPA2 mRNA expression, while TNF-alpha resulted in a 6-fold increase, and both of these effects were confirmed at the protein level. PGE2 resulted in a 14-fold upregulation of PAPPA2 mRNA but this was not reflected at the protein level. Forskolin, TGF-beta and IL-1beta had no significant effect on PAPPA2 mRNA expression. We observed no effects of any treatment on PAPPA or ADAM12 expression.

CONCLUSION

Our study demonstrates that factors previously known to be highly expressed in preeclamptic placentae (PGE2 and TNF-alpha), contribute to the upregulation of PAPPA2. Hypoxia, known to occur in preeclamptic placentae, also increased PAPPA2 expression. These results are consistent with the hypothesis that PAPPA2 is upregulated as a consequence of placental pathology, rather than elevated PAPPA2 levels being a cause of preeclampsia.

Altered placental expression of PAPPA2 does not affect birth weight in mice

BACKGROUND

Pregnancy-associated plasma protein A2 (PAPPA2) is an insulin-like growth factor binding protein (IGFBP) protease expressed in the placenta and upregulated in pregnancies complicated by pre-eclampsia. The mechanism linking PAPPA2 expression and pre-eclampsia and the consequences of altered PAPPA2 expression remain unknown. We previously identified PAPPA2 as a candidate gene for a quantitative trait locus (QTL) affecting growth in mice and in the present study examined whether this QTL affects placental PAPPA2 expression and, in turn, placental or embryonic growth.

METHODS

Using a line of mice that are genetically homogenous apart from a 1 megabase QTL region containing the PAPPA2 gene, we bred mice homozygous for alternate QTL genotypes and collected and weighed placentae and embryos at E12.5. We used quantitative RT-PCR to measure the mRNA levels of PAPPA2, as well as mRNA levels of IGFBP-5 (PAPPA2's substrate), and PAPPA (a closely related IGFBP protease) to examine potential feedback and compensation effects. Western blotting was used to quantify PAPPA2 protein. Birth weight was measured in pregnancies allowed to proceed to parturition.

RESULTS

PAPPA2 mRNA and protein expression levels in the placenta differed by a factor of 2.5 between genotypes, but we did not find a significant difference between genotypes in embryonic PAPPA2 mRNA levels. Placental IGFBP-5 and PAPPA mRNA expression levels were not altered in response to PAPPA2 levels, and we could not detect IGFBP-5 protein in the placenta by Western blotting. The observed difference in placental PAPPA2 expression had no significant effect on placental or embryonic mass at mid-gestation, birth weight or litter size.

CONCLUSIONS

Despite a significant difference between genotypes in placental PAPPA2 expression similar in magnitude to the difference between pre-eclamptic and normal placentae previously reported, we observed no difference in embryonic, placental or birth weight. Our results suggest that elevated PAPPA2 levels are a consequence, rather than a cause, of pregnancy complications.

[Surgical techniques for benign goiter]

For surgical therapy of benign thyroid diseases several different procedures are available. The specific use of these techniques depends on the particular morphologic and functional findings. Tissue that is benign is left in place as far as possible - pathologically changed tissue has to be removed. Practicable operation techniques are: excision or enucleation of solitary thyroid nodule, upper or lower pole resection, subtotal resection, near total resection and hemithyroidectomy.

Loss of wild-type MEN1 gene expression in multiple endocrine neoplasia type 1-associated parathyroid adenoma

Multiple endocrine neoplasia type 1 (MEN1) is a human hereditary tumor syndrome characterized by the development of endocrine adenomas of the parathyroid, anterior pituitary, and enteropancreatic tissue. Several lines of evidence have implicated the recently identified MEN1 gene located on chromosome 11q13 as a recessive tumor suppressor gene. Here, we analyzed MEN1 wild-type gene expression in tumors from a large MEN1 kindred. A deletion of codons 227-228 (678del6) located in exon 4 was found in tumor and peripheral blood complementary DNA using a simplified single-strand conformational polymorphism (SSCP) approach well suited for clinical MEN1 mutation screening. The identified 678del6 cDNA mutation deletes a potential phosphorylation site (Tyr227) and corresponds to a germ line mutation co-segregating with disease phenotype in this MEN1 family. Loss of heterozygosity analysis by fluorescent microsatellite PCR showed an exclusive loss of the MEN1 wild-type (and retention of the mutated) allele detectable in DNA from microdissected parathyroid and pancreatic, but not in adrenal, adenomas. Our findings confirm the synergism between MEN1 gene mutations and subsequent MEN1 allelic losses in the tumorigenesis of MEN1-associated adenomas.

Menin mutations in the diagnosis and prediction of multiple endocrine neoplasia type 1

INTRODUCTION

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by the development of multiple endocrine adenomas, typically in the pancreas, anterior pituitary, and parathyroid glands. The disease is associated with germ-line mutations of the menin gene, a putative tumor-suppressor gene located on human chromosome 11q13.

METHODS

To facilitate the diagnosis and prediction of MEN1 in patients and their relatives, we developed a molecular two-step strategy to screen for menin gene mutations. DNA fragments covering the entire menin coding sequence are generated from patient cDNA by polymerase reaction (PCR) and subsequently analyzed by single-strand conformational polymorphism electrophoresis (SSCP). Fragments with aberrant SSCP migration are DNA-sequenced to directly characterize menin mutations. In a second diagnostic step, genomic DNA of healthy relatives of the corresponding MEN1 index patient is analyzed by PCR, with only the specific exon amplified harboring the family-specific mutation. Mutation-specific restriction enzyme digestion of this PCR product finally allows the identification of mutation carriers through pathological restriction fragment patterns.

RESULTS

Using this approach, we identified an in-frame deletion mutation (delta Tyr Met) located in menin exon 4 (codon 227-228) that co-segregates with the disease phenotype in a large MEN1 family from Southern Germany.

CONCLUSION

It is likely that the direct molecular analysis of menin gene mutations will replace the genetic and biochemical screening tests currently used in the clinical management of MEN1 families. In addition, these studies may provide clues to the tumor biology of both sporadic and MEN1-associated endocrine adenomas.

Successful allotransplantation of microencapsulated parathyroids in rats

Allotransplantation of parathyroid tissue in humans is desirable for treating long-term hypoparathyroidism (e.g., after inadvertent removal of parathyroid glands during thyroid surgery). Until now, parathyroid allotransplantation was not used clinically because its advantages were outweighted by the need of immunosuppression. To overcome the immunogenicity of the tissue to be transplanted, we employed the method of microencapsulation; first tried in islet cell transplantation for experimental allotransplantation of parathyroid tissue. We have been able to achieve long-term success in a rat model. After isolation and tissue culture, tissue pieces from parathyroid glands of 280 Lewis rats were encapsulated in barium alginate and grafted into hypocalcemic DA rats. From the 7th to the 90th day after transplantation the recipient rats (DA rats) showed a normal serum calcium concentration. This is the first report of successful long-term survival and function of microencapsulated allotransplanted parathyroid tissue.

[54 consecutive duodenopancreatectomies without fatality]

Over a five-year period (1.1.89-31.12.93), a duodenopancreatectomy (Whipple's operation) was performed without hospital or 30-day death in 54 consecutive patients (22 women, 32 men; mean age 62 [27-82] years). The postoperative morbidity was 39% (21 of 54 patients). The indications for the operation were malignant tumour (n = 41), mainly ductal adenocarcinoma of the pancreas (n = 30), benign tumour (n = 5) or inflammatory head of the pancreas tumour in chronic pancreatitis (n = 6). A classical Whipple's operation was performed in 36 patients, while the stomach-preserving variant was undertaken in 18. The main complications were postoperative disorders of gastric emptying (n = 13), bleeding (n = 7), abscess (n = 4), leakage at the pancreas anastomosis (n = 3) and pancreatic fistula (n = 2). All complications were successfully overcome by early use of interventional methods or relaparotomy. -The low mortality rate of Whipple's operation (0-5% in selected centres) justifies the use of this operation even in advanced malignancies.

[Diagnostic and therapeutic procedures in splenic and hepatic artery aneurysms]

The diagnosis and therapy of splenic and hepatic artery aneurysms is besides clinical findings based on ultrasound and selective arteriography. Surgical treatment depends on the exact localization of the aneurysm. Because of postsplenectomy sepsis preservation of spleen should be reached. Otherwise splenectomy with resection of the aneurysm must be performed. If the aneurysm is localized at the common hepatic artery ligation of the vessel is possible. The interposition of an autologous vein graft is the most favorable proceeding in aneurysms of proper hepatic artery. Those of intrahepatic arteries should be treated just as aneurysms in high risk patients by selective percutaneous embolization.

[Cystic parathyroid gland adenomas: pathologic-anatomic variants of parathyroid gland adenomas or a separate disease entity?]

Between 01.01.1987 and 31.12.1990 a primary operation was performed on 126 patients in the Dept. of General Surgery, University of Marburg Hospital for primary hyperparathyroidism due to a parathyroid adenoma. Their clinically relevant data were prospectively documented. In 6 patients (4.8%) a total of 7 cystic parathyroid adenomas was found. While there was no difference in age- and sex-distribution, patients with cystic adenomas were found to have markedly higher serum parathormone and alkaline phosphatase levels than patients with solid adenomas. Calcium levels were similar in both groups. Cystic adenomas were much heavier than solid adenomas. A significant number of cystic adenomas was found to be displaced into the posterior mediastinum. The property of cystic parathyroid adenomas to be frequently located away from their usual anatomical position can make the intraoperative search for them difficult.

Subtotal parathyroidectomy versus total parathyroidectomy and autotransplantation in secondary hyperparathyroidism: a randomized trial

In a randomized study subtotal parathyroidectomy (sPTX) was compared with total parathyroidectomy and autotransplantation of fresh tissue (PTX + AT) in 40 patients with severe secondary hyperparathyroidism (HPT). After surgery both groups were followed at 19 +/- 6 months (PTX + AT) and 19 +/- 7 months (sPTX) and at 43 +/- 9 months (PTX + AT) and 40 +/- 7 months (sPTX). There were 17 patients alive in each group at the time of the second follow-up. After sPTX, 2 patients required re-operation because of recurrent disease originating from the remaining parathyroid gland in the neck and another 2 patients were hypercalcemic at follow-up. After PTX + AT both serum calcium and alkaline phosphatase normalized significantly more often (p less than 0.03) than after sPTX. Re-operations were not required in this group. Radiological signs also improved significantly more after PTX + AT, as did clinical signs like pruritus (p less than 0.005) and muscle weakness (p less than 0.04). These results and the fact that in recurrent disease a re-operation at the autograft in the forearm is simpler than a re-operation in the neck, lead to the recommendation that PTX + AT should be considered as the method of choice in the surgical treatment of secondary HPT.

Replantation of cryopreserved human parathyroid tissue

Twenty-five patients with permanent postoperative hypoparathyroidism received cryopreserved parathyroid autografts. Twelve patients had undergone cervical re-operations due to persistent or recurrent hyperparathyroidism and 10 patients had malfunction of a fresh autograft after total parathyroidectomy. Hypoparathyroidism occurred in 2 patients after subtotal parathyroidectomy and in 1 after the resection of a solitary adenoma following previous thyroid resection. The viability of the tissue was examined histologically prior to replantation in 22 patients and the amount of tissue needed for transplantation was determined by the ratio of necrotic cells vs. viable cells in the material. The patients were examined between 6 months and 125 months (median: 40 months) after replantation. Pre-operatively each patient required high doses of calcium and vitamin D metabolites to establish normocalcemia. This medication was reduced postoperatively, with 16 patients requiring no supplemental treatment. Nine patients still needed low doses of calcium and/or vitamin D. At follow-up all patients were free of hypocalcemic symptoms. Our results demonstrate that replantation of autologous cryopreserved parathyroid tissue is safe and effective therapy for permanent postoperative hypoparathyroidism. Thus, we regard it as an essential part of today's parathyroid surgery.

Lymph node counts in the upper abdomen: anatomical basis for lymphadenectomy in gastric cancer

The number of regional lymph nodes was determined in sites relevant to lymphadenectomy in gastric cancer in 30 cadavers. Tissue was cleared by dissolving fatty tissue, thus making lymph nodes with a diameter of at least 1 mm visible. All lymph node stations indicated by the Japanese Research Society for Gastric Cancer were studied. In stations 1-11 (corresponding with R2 resection) an average of 27 nodes (range 17-44 nodes) was found, whereas stations 1-16 (corresponding with R3 resection) showed an average of 43 nodes (range 25-64 nodes). These values are higher than those usually obtained from lymphadenectomy for gastric cancer. Striking individual differences in the total number of lymph nodes and the number of single stations was observed. The number of lymph nodes in these investigations are the normal anatomical values and serve as quality control of lymph node dissection in gastric carcinoma.

[Subtotal parathyroidectomy versus total parathyroidectomy with autotransplantation in secondary hyperparathyroidism. A randomized study]

In this randomised study subtotal parathyroidectomy (PTX) is being compared with total parathyroidectomy including autotransplantation (PTX + AT) in 40 patients with secondary hyperparathyroidism. Both groups were followed up twice, first 19 +/- 6 months (PTX + AT) respectively 19 +/- 7 months (subtotal PTX) and secondly 43 +/- 9 respectively 40 +/- 7 months after surgery. In each group there were 17 patients alive at the time of the second postoperative follow-up. In the meantime 2 patients with subtotal PTX required reoperation because of recurrences originating from the remaining parathyroid tissue, another 2 patients of this group were hypercalcaemic. After PTX + AT serum-calcium normalized significantly more often (p less than 0.03), a corresponding result was seen in alkaline phosphatase. Reoperation was not required in this group. Also radiological alterations reformed significantly more often after PTX + AT, so did clinical signs like pruritus (p less than 0.005) and muscular weakness (p less than 0.04). Considering these results and the fact that in case of recidive a reoperation of the autograft in the forearm is much easier to perform than a reoperation in the neck, PTX + AT is recommended as method of choice in surgical treatment of sHPT.

[Long-term results after implantation of autologous cryopreserved parathyroid tissue]

Autologous cryopreserved parathyroid tissue was implanted into 25 patients (12 men and 12 women, median age 45 [24-75] years, and an 18-month-old child) who after a parathyroidectomy for primary or secondary hyperparathyroidism, had developed permanent postoperative hypoparathyroidism. In 12 of the patients it had developed after a second operation for persisting or recurrent hyperparathyroidism. In ten patients it had occurred after total parathyroidectomy and autologous transplantation of fresh parathyroid tissue, in two patients after subtotal parathyroidectomy and in one patient after excision of a solitary parathyroid adenoma following goitre resection. In 22 patients the state of the tissue to be implanted was examined histologically before implantation after defrosting and any necrosis made up by replacement with more than 20 tissue particles. Re-examination took place a median of 40 [3-120] months postoperatively. The high doses of calcium and vitamin D preparations required preoperatively were reduced stepwise in all patients, completely discontinued in 16. At the time of follow-up nine patients were still receiving low doses of calcium and/or vitamin D. Symptoms of hypocalcaemia disappeared in all patients. Thus implantation of autologous cryopreserved parathyroid tissue is a reliable method for the treatment of permanent postoperative hypoparathyroidism.

Extracorporeal gas exchange in adult respiratory distress syndrome: associated morbidity and its surgical treatment

Extracorporeal carbon dioxide removal (ECCO2-R) over a membrane lung is a new therapy for patients with adult respiratory distress syndrome (ARDS) who frequently suffer from lung complications caused by long-term artificial ventilation and who may require major thoracic surgery. This is a report of 76 patients with severe ARDS who were treated by ECCO2-R. Twenty-six of these 76 patients required thoracotomy: 19 for pneumothorax and pneumatocele, and seven for haemothorax, infected lung necrosis or oesophagotracheal fistula. Most pneumothoraces were bilateral. Ten of these 26 patients required reoperation, usually for extensive persisting alveolar air leaks. Sixteen (62 per cent) of the 26 patients who had a thoracotomy and 22 (44 per cent) of the 50 patients without surgery survived. These results demonstrate that performing a thoracotomy, if necessary, does not diminish the survival chance of high-risk patients with severe ARDS.

[Lessons from reoperations in 55 patients with primary hyperparathyroidism]

On the basis of 70 re-operations in 55 patients (34 women, 21 men, median age 58 [43-83] years) suffering from primary hyperparathyroidism the reasons for failure of the first operations were analysed. The main reasons were inadequate exploration of the neck (failure to identify all four glands), failure to recognize multiple gland involvement, or inadequate resection in cases where more than one gland was affected. An abnormally situated gland was a less common cause, as shown by the fact that 41 out of the 73 glands removed at the last re-operation were situated in the normal position or in its immediate vicinity; in 20 cases the surgeon had failed to recognise multiple gland disease. Next in order of importance were anatomical variations in the location (32 out of 73 tumours) or the number of the glands (9 patients with hyperplasia of 5 glands). At the re-operations 89% of the parathyroid tumours were found in the neck region or would have been accessible from the neck at the time of the first operation. Overall, the hypercalcaemia was permanently rectified in 96.6% of the patients. During the last 10 years 94% of patients have been normocalcaemic postoperatively, thanks mainly to the re-implantation of autologous parathyroid tissue, preserved by low-temperature storage. The incidence of permanent unilateral recurrent nerve paresis attributable to the re-operations was 6%.

[Simplified storage procedure of cryopreserved human parathyroid tissue]

Parathyroid tissue that is stored for replantation purposes is usually kept in a special tank containing fluid nitrogen at -196 degrees C. Our studies demonstrate that storage is also possible in a deep-freezer at -70 degrees C without any loss of quality. Most hospitals own such freezers for storing bone marrow cells at the same temperature. Parathyroid tissue of 11 patients who were operated on because of primary hyperparathyroidism was stored in this way. After six months the tissue showed 75.7% morphologically intact cells. The control group's tissue was stored in liquid nitrogen according to the common method; after the same period of time it showed 76% histologically normal cells.

[Primary hyperparathyroidism. A disease picture has changed]

Data were retrospectively analysed on 544 consecutive patients (362 females and 182 males, mean age 53.6 [2 weeks and 86 years]) who had been operated on for primary hyperparathyroidism between 1965 and 1989. During this period the rate of renal, bone and intestinal complications decreased from 90% in the first 5 years to 29% in the last 5 years. Organ manifestations and hypercalcaemia were often combined (70% in the early period, 30% now). The proportion of those with an asymptomatic course gradually and continuously rose to 21% now. The patients' average age at diagnosis rose from 46 +/- 10 to 58 +/- 14 years. Serum calcium concentrations in the last few years averaged 3.1 mmol/l, as high during the last few years as at the beginning of the period. Age, serum calcium concentration and parathyroid weight of the asymptomatic patients did not differ from those of the group as a whole.

[Surgical therapy of lung complications of long-term ventilation for severe adult respiratory distress syndrome]

Long-term respiratory therapy with high pressure levels in case of ARDS can lead to several symptoms requiring surgical treatment. Various forms of manifesting barotrauma predominate (bronchopleural fistula, pneumothorax, pneumatocele and soft tissue emphysema), while hematothorax, infected necrosis of parenchyma or esophagotracheal fistula are rare. Most of the operations became necessary because of bronchopleural fistula resp. pneumothorax, and with this indication the number of reoperations was especially high. Of 21 patients 13 (62%) survived.

[Normal value of the number of lymph nodes in the epigastrium. An anatomic study for lymphadenectomy in stomach cancer]

The number of regional lymph nodes relevant for lymphadenectomy in gastric cancer was investigated in an autopsy study. In group N1-16 as described by JRSGC on the average 43 lymph nodes were found (range 25 to 64 lymph nodes). For group N1-11 (R1 and R2 resection, compartments I and II respectively) 27 lymph nodes were found on the average (range 17 to 44 lymph nodes). The results differed considerably in total number as well as within each single group and in the groups N1-16/N1-11. These results can be taken as statistical standard values.

[Reoperations in persistent and recurrent secondary hyperparathyroidism]

Among 181 patients who had been surgically treated in the Department of Surgery, Mainz University, for secondary hyperparathyroidism between 1975 and 1986, 33 had to be reoperated because of persistent or recurrent disease or because of failing autotransplanted tissue after total parathyroidectomy and autotransplantation. In 17 patients 26 reoperations had to be performed in the neck; in 9 patients, 3 of whom are already included in the group mentioned before, autotransplanted tissue had to be reduced eleven times. In another 10 patients autologous, cryopreserved tissue was replanted. 15 of the 17 patients reoperated in the neck became normocalcaemic, postoperatively, as well as 7 out of 9 patients in whom the autotransplanted tissue had been partially taken off. The results with replantation of cryopreserved tissue are being published in a separate article in this volume.

Food-induced histaminosis as an epidemiological problem: plasma histamine elevation and haemodynamic alterations after oral histamine administration and blockade of diamine oxidase (DAO)

In a randomized controlled trial, 30 pigs were orally treated with histamine (60 mg). In addition, half of the animals underwent a specific blockade of the enzyme diamine oxidase (DAO), which is the main histamine catabolising enzyme in the intestinal tract. Only these DAO-blocked animals exhibited severe clinical symptoms (e.g. hypotension, flush, vomiting) and, in parallel, showed tremendous elevations of plasma histamine levels of up to 160 ng/ml. 3 out of 15 animals in this group died within the experimental period. In contrast, the control animals neither exhibited plasma histamine levels above 5 ng/ml nor had any clinical reactions. These results contradict the current opinion that oral histamine intake in food is not clinically relevant, especially since many commonly used drugs are DAO-inhibitors and approximately 20% of our population take these drugs. Apart from drugs, some other factors (alcohol, spoilt food etc.) can also function via a blockade of DAO as an additional risk. DAO-blockade is therefore a real epidemiological problem. Evidence is presented here for the new disease concept: Food-Induced Histaminosis.

Reoperations for persistent and recurrent secondary hyperparathyroidism

Forty-nine reoperations for persistent or recurrent secondary hyperparathyroidism (HPT) in 30 patients are reported. The patients are part of a total of 184 patients operated on for secondary HPT; 28 reoperations in 18 patients were performed in the neck or in the upper mediastinum for remaining glands. Eleven reoperations at the forearm autograft revealed hyperplasia of the grafted tissue as the reason for recurrent disease in seven patients; they were treated by excision of all grossly enlarged particles. Ten patients received autologous cryopreserved tissue because of permanent postoperative hypoparathyroidism. The rate of graft-dependent recurrent HPT was 7%, and inadequate graft function was found in 6% of the patients.

[Results of treatment of ulcer hemorrhages]

The results of 270 patients, admitted from 1978 to 1985 because of upper gastrointestinal bleeding from ulcers or erosions were analysed retrospectively. Chronic peptic ulcers were the most common bleeding sites (192 patients, 71%). 49 patients (18%) bled from acute lesions and 29 (11%) from drug-induced ulcers. 53% of all patients exhibited an oozing hemorrhage (type Forrest 1 b) during emergency endoscopy. Within the eight-year-period hospital mortality dropped from 18% to 8%. In parallel the prognosis of oozing bleeding improved. In this period the patients were more often treated with secretin or somatostatin. Hence the frequency of emergency operations for patients with oozing bleeding could be reduced from 44% in 1978 to 10% in 1985 and the death rate from 22% to 5%.

The effect of oxotremorine on in-vitro secretion of parathyroid hormone

The effect of the muscarine-like acting parasympathomimetic drug oxotremorine and its antagonist atropine on PTH release was tested using single cell suspensions obtained from a) primary parathyroid adenomas, and b) secondary hyperplastic parathyroid tissue from patients undergoing chronic hemodialysis. For both cell-types we found a dose-dependent suppression of PTH release with oxotremorine. The suppressive activity could be antagonized with atropine, suggesting that parasympathomimetic nerval impulses play a suppressive role in the regulation of PTH release. Muscarine-receptors appear to be responsible for this mechanism.

The effect of high parathyroid hormone concentration on calcitonin in patients with primary hyperparathyroidism

Serum calcitonin (CT), parathyroid hormone (PTH), and calcium levels were measured in 23 patients with primary hyperparathyroidism. PTH was determined by a midregion (M-RIA) and a carboxyl-terminal (C-RIA) specific PTH-RIA. Only 2 patients had elevated CT levels. In contrast to the findings in 46 healthy controls, the CT levels did not correlate with calcium levels. Patients who had the highest iPTH values showed a negative correlation between CT and iPTH (M-RIA (n = 7): R = -1.0000, p less than 0.001; C-RIA (n = 13): R = -0.5604, p less than 0.05). The results of the C-RIA were subtracted from those of the M-RIA. In 12 patients with the highest levels of intact PTH (M-RIA - C-RIA), serum PTH concentration was inversely correlated with serum CT concentration (R = -0.7343, p less than 0.01). In the same patients a negative correlation between CT and calcium was found (R = -0.6783, p less than 0.02). These findings suggest that high PTH levels may have a direct suppressive effect on CT concentration and this may be, at least in part, responsible for failure of CT concentrations to rise in many patients with primary hyperparathyroidism.

[Reoperations in persistent and recurrent secondary hyperparathyroidism]

Forty-seven reoperations for persistent or recurrent secondary hyperparathyroidism (HPT) in 29 patients are reported. The patients are part of a group of 181 patients operated on for secondary HPT between 1975 to 1986. Most reoperations were performed in the neck (26 operations in 17 patients). The main cause were remaining parathyroid glands in the mediastinum (9 patients), followed by normally localized glands in the neck, which had not been discovered during previous operations. In 7 patients a hyperplasia of the autografted tissue was the reason for recurrent disease. They were treated by resection of the autograft. In 10 other patients autologous cryopreserved parathyroid tissue was reimplanted because of persistent postoperative hypoparathyroidism.

[Replantation of autologous cryopreserved parathyroid tissue in permanent postoperative hypoparathyroidism]

Cryopreserved autologous parathyroid tissue was reimplanted into 16 patients with permanent postoperative hypoparathyroidism. In 13 cases the number of necrotic cells in the thawed cryopreserved tissue was determined histologically and compensated by using a greater amount of tissue particles during re-implantation. These patients had normal transplant functioning after a median period of 6 months. On the other hand, delayed onset of functioning of the autotransplant was seen if the rate of necrotic cells had not been compensated. The results show that re-implantation of autologous cryopreserved parathyroid tissue is a suitable method for treating permanent postoperative hypoparathyroidism. The method should be used as a firmly established part of parathyroid surgery.

[Asymptomatic hyperparathyroidism. An indication for surgery?]

From 1965 to 1985, 412 patients were operated on for primary hyperparathyroidism (pHPT). Of these, 35 (8.7%) were without specific symptoms and findings. The follow-up investigations after six months to 14 years (median: 31 months) revealed a normalization of the preoperative pathological parameters of alkaline phosphatase, uric acid, creatinine and hypertension in the majority of patients apart from the improvement of their general condition. All patients were normocalcemic. According to these results, the indication for early surgical therapy of the asymptomatic pHPT is to be advocated in order to avoid long-term complications.

The influence of parathyroid hormone and its fragments on results from midregion and C-terminal specific radioimmunoassays

We compared a midregion (44-68) human parathyroid hormone (hPTH) specific radioimmunoassay (M-RIA) with a C-terminal (65-84) hPTH specific radioimmunoassay (C-RIA). The M-RIA discriminated 21 of 23 patients with primary hyperparathyroidism from 95 normals (normal range: 22.4-106.5 pmol/l). With the C-RIA 12 patients including the 2 patients not discriminated by the M-RIA had immunoreactive PTH (iPTH) values within the normal range of this assay (normal range: undetectable to 88.6 pmol/l). To investigate the reasons for these different abilities of separation, hyperparathyroid sera were subjected to gel-filtration and analyzed using the two assays. Intact PTH appeared to have a major influence on the immunoreactivity of circulating PTH in the M-RIA. In contrast, the C-RIA showed the highest immunoreactivity with midregion-C-terminal PTH fragments. Hyperparathyroid sera not discriminated by the C-RIA but with elevated iPTH in the M-RIA showed decreased amounts of midregion-C-terminal PTH fragments, while intact PTH comprised the highest amount of total circulating PTH immunoreactivity in the M-RIA. From the present results we conclude that the superiority of the M-RIA is due to the determination of intact PTH which is preferable for clinical measurements with relation to the diagnosis of primary hyperparathyroidism.

The secretion of parathyroid hormone and its fragments from dispersed cells of adenomatous parathyroid tissue at different calcium concentrations

The effect of varying calcium concentrations on PTH release from dispersed cells of adenomatous parathyroid tissues (n = 15) was studied. During high calcium concentrations PTH secretion was inhibited up to 62.5% as compared to low calcium concentrations. There was no correlation between iPTH secretion rate and suppressibility. Each adenoma had a different iPTH secretion rate. Three adenomas showed a high suppressibility (28.0%, 53.8%, and 62.5%). The supernates of their media were chromatographed and examined by midregion and C-terminal specific PTH-RIAs. Carboxyl-terminal PTH fragments were found to be released by two adenomas. There was no evidence for the release of midregion PTH fragments. Comparison of incubation media revealed that the adenoma with the lowest suppressibility released the highest amount of intact PTH (per 100,000 cells/ml). This adenoma exclusively secreted intact PTH, whereas PTH fragments were only released from two adenomas with higher suppressibility. In these media the ratio of PTH fragments to intact PTH increased with the calcium content of the media. The ratio was also dependent on the suppressibility of the adenomas; i.e. the ratio was greater when the suppressibility was higher. This suggests that in adenomas the intracellular hormone degradation is responsible for the degree of PTH suppression. As the suppressibility of PTH secretion is reduced in hyperfunctioning parathyroid tissue, diminished intracellular hormone degradation seems to be involved in the pathogenesis of primary hyperparathyroidism.

[Simplified procedure for cold preservation of human parathyroid gland tissue for replantation]

A simplified technique for cryopreservation of human parathyroid tissue is described. It allows to achieve the same quality of tissue than using the programmable expensive freezing method which is usually employed up to now. Cryovials are placed in a methanol bath. The temperature is decreased by -1 degree C/min down to -25 degrees C, thereafter by -10 degrees C/min down to -70 degrees C by repeated adding of cryo ice-cubes into the methanol. Thereafter the vials are stored in LN2. The temperature lowering is controlled by a stop watch and a thermometer in a reference vial. This simple and cheap technique may allow a more general application of cryopreservation in surgery of hyperparathyroidism.

The effect of cryopreservation on hormone secretion in vitro and morphology of human parathyroid tissue

The hormone secretion from human parathyroid tissue autografted after cryopreservation can fail frequently. In this study we examined the effects of the cryopreservation procedure on parathyroid hormone secretion in vitro and the viability of parathyroid cells to identify possible reasons for graft failure. Cryopreservation did not affect quantitative parathyroid hormone release from single-cell suspensions or its calcium-and magnesium-dependent regulatory mechanisms. However, morphometric analysis of thawed 1 mm3 graft particles showed various degrees of necrosis when compared with fresh grafts. Thus partial necrosis of cryopreserved tissue appears to contribute to poor transplantation results compared with immediate replantation of fresh parathyroid tissue. This limitation can be overcome by increasing the number of frozen graft particles used for autotransplantation. The percentage of viable cells should be accounted for by morphometric analysis and this factor used when calculating the number of graft particles employed.

[Artificial respiration in a surgical intensive care unit]

An indication for respiratory treatment is given in manifest and for prophylactic mechanical ventilation in expected pulmonal insufficiency. The mortality rate can be reduced by an early respiratory treatment, therefore prophylactic mechanical ventilation should be performed liberally. Mainly patients after abdomino-thoracal operations and major vascular or upper abdominal surgery are at risk for lethal postoperative pulmonary complications.

[Embolization of a pseudoaneurysm of the hepatic artery with hemobilia by direct percutaneous puncture]

Haemobilia is a rare cause of gastrointestinal bleeding that carries a high mortality. It occurs as a complication of percutaneous trans-hepatic biliary drainage in up to 6% cases. The cause is usually a pseudo-aneurysm of the hepatic artery, which can be treated by trans-catheter embolisation. If this fails, direct puncture and embolisation of the aneurysm is a possible alternative to surgical ligation of the hepatic artery.

[Autotransplantation of cold preserved human parathyroid gland tissue. Indications--technic--results]

Autotransplantation of cryopreserved tissue is of increasing clinical value after parathyroid surgery became more common. The results in the literature show a high rate of non functioning grafts after autotransplantation of cryopreserved tissue in comparison to fresh autografted tissue. The reason for that is a partial necrosis of the tissue caused by the freezing and thawing process. To obtain better results after autotransplantation of cryopreserved tissue the rate of necrosis should be estimated. The loss of functioning cells should be compensated by autografting a greater amount of tissue fragments.

Xanthogranulomatous cholecystitis mimicking carcinoma of the gallbladder: CT findings

The CT findings in a case of xanthogranulomatous cholecystitis are reported. Irregular thickening of the gallbladder wall and poorly defined borders of the underlying liver and the adjacent duodenum suggested a tumorous lesion.

[Cryopreservation of human parathyroid tissue. Effect of in vitro secretory behavior and morphology]

The effects of cryopreservation on in vitro secretion and on the survival rate of parathyroid cells were investigated, in order to find possible causes for the frequent failure of autologous, human parathyroid tissue. A reduction in the hormone secretion or an influence on the secretion could be excluded. The freezing procedure, however, leads to a partial necrosis of the tissue. Similarly good results, as in the replantation of fresh tissue, can be achieved by compensating the necrotic cells using more particles.

[Perioperative antibiotic prophylaxis (single or multiple dose) in elective colorectal surgery. A randomized study]

In a randomized trial in 60 patients undergoing elective colorectal surgery the efficiency of intravenous antibiotic short time prophylaxis was determined. We compared single dose application with multiple dose prophylaxis for 24 h. The substance used was cefotaxime. The rate of wound infections was comparable in both groups (16.6 vs. 13.3%) as well as postoperative infections of the urinary tract (33.3 vs. 23.3%). The results of the study suggest that single dose prophylaxis is as efficient as multiple dose application to reduce postoperative infections in elective colorectal surgery.